LaserBoy

Hardware => DACs => Topic started by: emanuel on June 30, 2015, 05:11:55 am

Title: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on June 30, 2015, 05:11:55 am

hi James,


I've got a 500mW RGB + 25k sdcard laser unit (Emma Lights EM RGB 222) and a raspberry PI 2.


I want to build an DAC interface for those in order to use laserboy. Do you still ship the kit?


If yes, how can I get one?


And what 7.1 soudcard to buy ? Have you got a link?


thank's Emanuel  ;)
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: BlinkenLights on June 30, 2015, 08:01:39 pm
He ships them and he may have sound cards too, if not this is the one that i think he is using (there are many "brands" but they all LOOK just like this one)
http://www.ebay.com/itm/like/331237914254?lpid=82&chn=ps
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on July 01, 2015, 04:24:49 am
@BlinkenLights


that is good. Here from Germany I could only find this one provided by lots of brands:
http://www.digitus.de/sv/produkter/multimedia/audio/usb-audio-adapter/71-usb-sound-box-da-70800/


http://www.logilink.de/Produkte_LogiLink/Eingabegeraete_Multimedia/Audio_Zubehoer/USB_Sound_Box_71_8-Kanal.htm

Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on July 01, 2015, 12:16:28 pm
It looks like that will work OK.

You have front L&R, center sub surround L&R and back L&R. That's all 8 channels.

What you are really looking for is the C-Media 6206 USB sound chip.

I think that device should be OK.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on July 01, 2015, 04:59:28 pm
@James thanks ,
I've found C-Media 6206 USB sound chip is inside.

And what about the amp kit? Do you still sell them?

How can I get one?
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on July 01, 2015, 05:29:46 pm
Yes. I still sell them.

I can put one in an envelope and weigh it. Where are you in the world?

The kit is $40 plus shipping.

What are you looking for in this forum? Maybe I can help.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on July 01, 2015, 07:33:47 pm
fine, what is the best way to pay?  :)

Im from Germany (Bavaria)

I'm looking for a lot n this forum ;D because I'm very new to RGB Lasers, real galvanos and ild.

In the late 80's I've played a lot with my NeHe + C64 + interface + positioning mirrows and other effects. In thouse days it was impossible for me to buy such things...

2015: The RGB is a nice toy. I've testet from sd card and from qlcplus (http://www.qlcplus.org/) (DMX), but this is all limitted to ttl at this time. For me as hobbyist it is not intresting to buy pangolin ...

I'm using Linux since the late 90's so LaserBoy is my favorit choice.

Also the wave file idea is very cool, because  qlcplus can start extern exec from macros. But first of all I've to learn more about the LB sw (setting for ~25k, ...)

a pic off my qlc laser test console:


Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on July 01, 2015, 09:42:48 pm
Ok.

Well, my first suggestion would be to get a nice inexpensive US English USB keyboard.

I put some thought into laying out the keys that make LB work. If you have a German keyboard, some of the glyphs might be in different places. Not sure about that.

There are some settings in the [Tab] menu and some in the x menu. [Tab] is where the value settings are and x is where the on / off settings are.

Of interest are the max lit distance and the max blank distance in points.

ILDA file standard vector images are made of 3D (or 2D) vertices stored as 16 bit signed integers. So space is a cube of 65536 points. If you consider the point (0, 0, 0) to be the center of space then you can forget about -32768, because there is no positive 32768!

So these max distance values are relative to that space. That is to say LB will interpolate points along straight lines and add points such that none of them are father apart than these values.

This is ultimately what controls the velocity of the scanners.

If each point is translated into a sample in a wave file and the sample rate of that wave is 48KHz. this is how far the scanner is expected to move in 1/48000 of a second.

If you are preparing art for that SD card reader, you should probably change the wave sample rate to something like 20000 or 25000 to match the DAC rate of the SD card reader.

You can also figure on increasing the distance between added points as the scanner will have a longer period between DAC cycles.

If you plan on using LB to optimize your art and save that as ILDA, you need to turn off the automatic minimization process in menu x. Otherwise LB will strip out all of the optimizations in your art and save a file of minimal size.

Another factor in the [Tab] menu is max dwell in microseconds. Since this value is time, it is relative to the wave sample rate setting. This factor is used to determine how long (how many samples) to sit in one place in corners of your image. The more acute the angle is, the more dwell points will be added. A full 180 degrees is the most acute any angle can be. Dwell gives the scanners time to come to a complete stop before moving off in another direction, so you see a nice clean angle rather than a sloppy curve.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on July 03, 2015, 08:09:06 am
german keyboard work typing correct keys. As I've compiled LB on ubuntu host?  :)


but setup ild for sdcard or iShow-prog-import-test still do not work.  :-[


I'll will try again...






Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on July 09, 2015, 04:18:51 pm
OK! I just sent you a built LaserBoy Correction Amp board.

I hope you get it soon. Let me know.

In the mean time we can work on the sound card that you have to get it ready for the correction amp.

Can you post some pictures of the sound device you have?

I would suggest using insulated solid copper telephone wire. I like to use red and black for the +5V USB power and the ground and then I use white, gray, red, orange, yellow, green, blue and violet for the direct outputs of all of the DAC channels 1 through 8.

If you use this solid copper wire, you can push it into the pin sockets of the correction amp inputs.

They hold quite well and this gives you the ability to swap out the channels that are different between Windows and Linux.

You will find that the default order of wave channels to DAC channels is different between Windows and Linux. Channels 5 & 6 are swapped with channels 7 & 8.

You might also find that channels 1 & 2 (X and Y) are also swapped on the sound device itself.

Once you find the decoupling capacitors for each DAC channel you should tack a wire onto the positive signal side of each cap.

http://laserboy.org/forum/index.php?topic=8.msg6336#msg6336 (http://laserboy.org/forum/index.php?topic=8.msg6336#msg6336)

With the sound device driver loaded in your OS, make sure the device is enabled for 8 channels of output.

In Windows, there is a control panel for the device driver. There you can specify that it is an 8 channel device. You also need to set up the Windows sound system to use 8 speakers.

You'll need to do some research to make sure the device is set to 8 channels in your version of Linux.

With no sound playing, you should be able to measure a small DC offset voltage on each of the direct outputs of the DAC; like +1.2 to +2.25 VDC with respect to the sound device ground.

This is the DC offset that the correction amp is designed to NULL out.

In LaserBoy there is a setting to invert wave output. This is the default setting. This means that positive numbers from the vector art; galvo positions and color signals, will be saved as negative numbers in the wave. This is because the correction amp is an inverter; negative times negative is positive.

So, if you make a wave file of frame 10, the big white circle, in LaserBoy, when you play it, you will see the voltage drop low on the color channels. You should also be able to measure some AC voltage on the galvo channels.

So, let's get to that point before we go on to adjusting the correction amp that you don't have yet.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on July 28, 2015, 06:08:10 am
I'm still waiting for it!  :-[
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on July 28, 2015, 01:11:10 pm
That sux.

This might help. I don't know if this works outside of the USA, inside of Germany, but here is the tracking number.

LC689247211US

It went out via USPS Customs form CN 22 on 07/09/2015 15:28

I just checked it online and it says that tracking is not available to Germany.

So that must mean that it is no longer in The USA. It must be in German Customs.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on July 28, 2015, 02:59:21 pm
hope so, yes, I've tested it, no tracking from Germany posible.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on July 30, 2015, 04:16:19 am
It was yesterday in the mail  ^-^
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on July 30, 2015, 09:05:06 am
Awesome!

Do you know how to adjust it?

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on July 30, 2015, 01:55:29 pm
not really, but fist I will buy wire to connect. And also I have to break my 5years Warranty 7.1 Case  >:D
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on July 30, 2015, 03:02:21 pm
pix:
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on July 31, 2015, 10:04:53 pm
That looks nice.

Do you know what to do next?

I like to use multi-colored insulated solid copper wire.

This wire plugs into the input pin sockets and stays in nicely.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 02, 2015, 12:43:46 pm
I've got multi-colored insulated solid copper wire.
Do you know what to do next?

>> no realy

I need to know how to connect the amp kit to the 7.1 channels, and the +5v/GND ...

Does it need external power too (12V)?
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 02, 2015, 01:40:17 pm
No. You use USB power.

Look at the back of where the USB jack is soldered. You should be able to find two solder spots. One of them will have continuity to the metal jacket of the USB port. That is ground. Having found ground, you should be able to find the +5VDC with your meter (with the sound card powered).

Then you need to look at all those capacitors that are near the audio output jacks. You should find that each one of them is connected in series with the signal contacts on those jacks.

So you should be able to measure continuity from the negative leads of each cap to the signal contacts on the audio jacks to properly identify which cap goes to which output.

The positive sides of each of those caps are connected directly to each channel of the DAC.

That's what you want.

If you tack wires on the positive sides of each of the audio decoupling capacitors you will have 8 wires that are each connected directly to the output of each channel of the 8 channel DAC.

With the sound device powered and the driver loaded in Windows, and the driver set to 8 channels, and the Windows sound system set up for 8 speaker output.....

You should be able to measure a small DC offset voltage on every one of those direct outputs from the DAC when there is no sound being played through the sound device.

It should be about +1.2 to +2.25VDC with respect to ground.

This is the DC offset that the correction amp is designed to NULL.

The correction amp does two things.

It sums a negative voltage with the input, NULLing the DC offset and it provides voltage gain to give you enough voltage to drive your laser projector.

It is also an inverting amp. So you make waves in LaserBoy that are inverted.

Inverted -> inverter = non-inverted.

You only need 6 direct outputs from the DAC for the correction amp, but you should find all 8 so that you can use your setup for Windows or Linux.

If you recall, I found that channels 5 & 6 get swapped with 7 & 8, between Windows and Linux.

I'm sure you can rearrange this in Linux. But it's just as easy to swap the wires.

Plus, all you need to do is put a 47uF capacitor in series with any one of those direct DAC outputs (+lead towards the DAC, -lead towards the audio output) and it becomes a valid audio output again.

This is not the board that you have, but it is a C-Media 6206 sound card.

http://laserboy.org/forum/index.php?topic=8.msg6336#msg6336 (http://laserboy.org/forum/index.php?topic=8.msg6336#msg6336)

Once you have found all of the direct outputs from the DAC, you should figure out a way to identify which channel each one is in a wave file.

You can use Audacity in any OS to make 8 channel waves.

You have to go into edit... preferences... Import / Export.... * use custom mix (for example to export a 5.1 multichannel file).

Then you can create up to 8 channels of waves in Audacity and export the whole thing as one wave file of 8 channels.

You cannot play the 8 channel wave in Audacity.

You have to find a wave player that will do that for you in your OS.

ALSA player can do it in Linux.

Spider Player does it in Windows.

http://laserboy.org/Spider_Player_2.5.3_Setup.exe (http://laserboy.org/Spider_Player_2.5.3_Setup.exe)

I think you will find that

front left and right are channels 1 & 2.

center / sub are 3 & 4.

rear left and right are (6 & 5 in Windows) ... (8 & 7 in Linux)

side left and right are (7 & 8 in Windows) ... (5 & 6 in Linux)

A good way to test this is by making a wave files in LaserBoy of the big white circle, frame 10.

If you make a 10 second wave of the white circle, it will play through Spider Player. You can set Spider Player to loop so it will just keep playing until you stop it. You should change the color of the circle to red, green and blue and makes waves of those colors as well.

Then you can test your sound card to see where the color signals come out.

X and Y for the galvos should always be on channels 1 & 2 == front left and right.

If you hook one meter lead to ground you can measure voltage changes on each of the direct outputs from the DAC.

Since LaserBoy makes inverted waves, by default, you should see the voltage offset drop to closer to zero volts on the color channels when a wave is playing and the wave contains an image that uses the color signal you are seeking. If you use the circle as a test wave, you should also be able to measure some AC voltage on the X and Y signal lines (front left and right).

...... hang on ....... more to come .........
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 02, 2015, 06:36:06 pm
ok, I've made first test on raspberry using alsa test 5.1. and a volt meter. looks good
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 02, 2015, 07:10:54 pm
OK.

Now you need to know how to adjust the correction amp!

Since you are using ALSA on a Raspberry Pi, you should know about alsamixer. It is possible to have digital gain in the driver of the sound device that is more than 1.0! This will cause the signals to clip coming from the sound card.

Set the maser volume to something like 70% before you do these adjustments.

Once you are done, you can fiddle with the master volume for the USB sound device in alsamixer and set it to the maximum value that does not clip the edges of the big white circle when you project it.

But, remember, when you change the master volume, you are also changing the volume of the color signals.

So you may need to re-adjust your gains on those channels to get back to +5VDC max (with no jumpers on).

This will make more sense if you read the whole thing before you start!




               ILDA PORT
            [:::::::::::::]
 * GND
   (Off) (Gain) [TLO72] (Off) (Gain)
        X       [opamp]    Green

 * V_off
   (Off) (Gain) [TLO72] (Off) (Gain)
        Y       [opamp]     Blue


   (Off) (Gain) [TLO72] (Off) (Gain)
       Red      [opamp]   Intensity


   (adj)        [-vreg]
                        power
                        * * *
                      GND | GND
         INPUT           +5V
      * * * * * *
      X Y R G B I


http://laserboy.org/forum/index.php?topic=561.0 (http://laserboy.org/forum/index.php?topic=561.0)

First of all, pull off the jumpers.

If you were starting with an amp that has never been adjusted, you should turn all the 500 ohm offset and voltage regulator adjust trim pots (7 of them) all the way down by rotating them several times counter clockwise. They are 25 turn pots. You might hear or feel clicking when they are all the way down.

Then turn all the 100K gain trim pots (6 of them) all the way up by rotating them several times clockwise.

This will set the gain of every op-amp channel to max (100K) and set the individual offset adjustments (500 ohm) to minimum.

Now take note of the voltage offsets you measured on each wire coming straight out of the DAC channels.

They should all be close to the same voltage.

Pick the lowest voltage.

Multiply this voltage by about -1.5.

This is close to the voltage you want to set on the variable negative voltage regulator.

There is a 500 ohm pot next to the negative voltage regulator.

You can put your meter between ground and the pin labeled V_off.

Turn the 500 ohm pot next to the voltage regulator until you measure a voltage that is -1.5 times the lowest offset voltage you measured from the DAC channels.

This will get you close.

You need to adjust this master offset voltage such that with each channel of the DAC connected to the correction amp, the outputs are very small voltages (like millivolts) but they are all still positive.

With the DB25 ribbon plugged into the amp, you can stick a wire into pin sockets 1, 2, 5, 6, 7 & 8.

1 & 2 are X and Y. 5, 6, 7 are Red, Green and Blue. 8 can be used as a mix of RGB for single color laser systems (intensity).

You need to make sure that you do not over correct with the negative voltage.

You can only add a little bit more negative voltage with the trim 500 ohm pots on each channel.

If you over adjust the voltage regulator to be too negative, you cannot compensate for it with the individual trim pots on each channel.

Since your 100K gain pots are all the way up, this will greatly amplify the results of your offset trim adjustments.

So, get as close as you can. It takes a while to let the voltage regulator settle and sometimes it helps to tap on the trim pots with a pencil or something.

Turning each one of the offset pots up will get you closer to zero volts on each channel. Try to get as close to zero volts as you can on each channel.

You have to keep checking each one several times. Let it sit for a while and come back and test it again.

Once you are happy that you are about as close as you can get you can turn the gain for X and Y way down. These signals drive your scanners.

This is where the wave of the big white circle is needed.

When you play this wave, you are sending full-on voltages to your color control signals. White is full on red, green and blue. You need to adjust the gain for each, red, green, blue and intensity to +5VDC when the wave is playing. Turn the gain pots (100K) down for each of the color channels until each one measures +5VDC.

After you set these voltages, you can put the jumpers back onto the correction amp. These jumpers put a 5V zener diode to ground on each of the color control signals so that they can never go over +5VDC. So make sure the jumpers are always on when you use the correction amp to drive your projector.

Also when the circle wave is playing, you should be able to measure some AC voltage on X and Y. If you turn the gains on these channels way down, you can hook up your laser projector and adjust these gains to control the size of the scanned image. X is width and Y is height. Adjust them to make a perfect circle.

Now make a wave of one of the frames in LaserBoy that is a recognizable image, like the LaserBoy Logo in frame 0 or Quisp in frame 35. Display it on your projector and make sure your X and Y are correct. If the image projects sideways, you need to swap the input wires for X and Y on the correction amp and maybe check the offset adjustments for those channels again.

Then you need to take some nice pictures and post them here!

You're done!

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 03, 2015, 05:46:12 pm
setup is ready for testing :-)
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 03, 2015, 07:43:56 pm
Looks good. Nice and neat.

Do my instructions make any sense?

Do you have any questions?

It's a good idea to take a black magic marker and mark the pin socket holes on the DB25 ILDA connector at locations 1, 2, 5, 6, 7 & 8. That way you can find them easily for measuring your voltages.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 04, 2015, 04:51:22 pm
min volt was 2,25 V on Channel 8 (Soundcard) so I put the amp to -3,37 V.


All other 500 Ohm down (not all do loop snapping at the bottom, while screwing down) , and all 100k up.

100k Pots: I can come with Ilda pin 1 and pin 2 closly to zero, but not with pin 8 (-0,5 mV at top, screwing down brings only more negativ volt), pin 7 (-1,3mV at top, screwing down brings only more negativ volt) pin 6 (+2,8mV at top, screwing down brings only more volt)


I can hear the circle wave on usbcard's output jack, but there is no signal to the ilda pins, playing that circle wave.


I've tryed diffrent alsamix settings 70% for all, 100% on line 70% on speaker, ..., more master offset less ... turning the amp's cannels 500Ohm pots


always same volt on the ilda pins :-(
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 04, 2015, 05:56:22 pm
One thing to know is that all six channels on the correction amp are exactly the same, except for the 5V zener diodes on the color channels. But if you pull the jumpers, they are not in the circuit.

So all channels should behave in the same way.

If you are measuring small negative voltages on some of your outputs, you have over compensated with the setting of the master negative voltage regulator.

You cannot compensate for too much negative voltage from V_off by adjusting the individual offset adjustments on each channel.

So you need to back off the setting on the negative voltage regulator a tiny bit such that all of the outputs from the correction amp (with the sound card attached) measure some small POSITIVE voltage. Then you can tweak out this small positive voltage by adjusting the individual offset adjustments on each channel.

One more thing that you need to know is that your multi-channel USB sound device might be mixing all of the 6 channels of the LaserBoy waves down to stereo and only outputting from the front left and right channels.

This happens in Windows, if you do not enable the USB sound device in the Windows driver to do 6 or 8 channels.

I'm not sure how you set this in Linux. But I know it can be done. I have my Raspberry Pi 2 set up this way and it works fine.

http://www.photonlexicon.com/forums/showthread.php/23778-controlling-scanners-standalone?p=309861#post309861

BTW, a few millivolts is very close to zero! Once you have your correction amp close to zero and you adjust the gain pots down to show +5VDC on the color channels and a reasonable scan size on the galvo signals when you play the wave of the big white circle, your offset voltages should be very close to zero volts.

Do you have access to an oscilloscope? That can be very useful.

I hope this helps.

I'm here to answer any more questions you might have.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 04, 2015, 09:55:38 pm
If you are interested, I can make an image of my micro SD card that boots my Pi2 so you could use that image. That way we would be on the same page.

It already has the C++ compiler installed with libSDL and Boost C++ libs, plus the LaserBoy folder is there with all the source code ready to compile.

That's the nicest thing about the Pi2. They are all exactly the same! :)

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 05, 2015, 04:27:53 am

Do you have access to an oscilloscope?
>> No
if you are interested, I can make an image of my micro SD card
>> could be helpfull, if nothing helps.
I'm using rasbian, sdl, boost, LaserBoy compiled on host.  I'll try again.


usb soundcard channels have at all min 2,25V, amp was -3,37V.
How mutch volts should I use to get better results on the RGB pins?
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 05, 2015, 12:42:42 pm
You might never get to exactly zero volts on any of the control signals. Millivolts is thousandths of a volt. That is very close to zero.

The effect that has on your laser projector is minimal.

If there is a tiny voltage, negative or positive, on the galvo signals, all that does is move the scanners a tiny bit off center when there is no signal. No big deal.

A tiny voltage on the color signals is not important either as long as the lasers are off when there is no wave playing.

You just need to get close to zero.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 05, 2015, 01:36:09 pm
Forget about the correction amp for a moment.

You should test your Raspberry Pi2 and sound device to make sure that you are really getting 6 or 8 channel playback.

You can use Audacity to make an 8 channel wave that has something different and recognizable in each channel. You might use a mic and record your own voice saying "One, Two..., Three, Four..." etc... for each channel. When you play it back through the sound device, make sure you hear the correct playback from each channel.

Then you will know that your sound system it working correctly.

Like I said before, it is possible that your device might be mixing all of the channels down to stereo and only outputting on channels 1 & 2 (front left and right).

Also note that when you send a wave to the sound device that is not all 8 channels, the outputs of the channels not assigned by the driver playing the wave are undefined. You cannot assume that they will be silent. When playing a 6 channel wave, it is likely that you will have the green and blue color signals coming from the undefined channels 7 & 8.

If you have your LaserBoy DAC hooked up to an audio system for music tracks in 7 & 8 and you play a 6 channel wave, you'll get color signals sent to your sound system.

LaserBoy has a setting to make 8 channel waves with all zeros in channels 7 & 8.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 05, 2015, 06:26:33 pm

It is very easy to test soundcard's jacks under raspberry linux using:


speaker-test -Dsurround71:Device -c6 -twav


all 7.1 jacks are in use while testing (headphones)
after that I'm using:


aplay -Dsurround71:Device C.wav


C.wav = the white circle at 20000 Hz.
It also brings up noice on headphone excluding the 2 channel that are not connected to the amp.
So soundcard works in 7.1, but amp not.


As I wrote I can come neer to zero at the channels, but while playing the wave there are no volts on the pins (1,2,5,6,7) of the DB25 respected to GND.
All channel values could only be changed using the black marked pots to come to the zero. All other cannel pots are dead.


There is not even a minimal change screwing the other pots X,Y,R,G.B (blue 500 Ohm), while playing the wave.


I've spent next 4 houres for nothing...


same as yesterday :-(
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 05, 2015, 07:21:43 pm
exact the same under Windows C.wav + spiderplayer loop-> no volts om DB25 pins  (cannels are the same as under linux in my case, not twisted), I think some part is not working on amp.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 06, 2015, 12:15:25 pm
Well, you know the negative voltage regulator is getting power.


        -[    ]-*
        -[    ]-
        -[    ]-
       *-[    ]-


Use your volt meter with one lead grounded and check for voltages on the IC sockets (from the top of the board). You should see something close to +9VDC and -9VDC.

That will tell you if the DC/DC converter is working.

The -9VDC must be working. It powers the negative voltage regulator.

I find it hard to believe that none of the channels of the correction amp are working.

I tested that board thoroughly and had it set for a USB SND8 that I have.

The SND8 offset voltage that I get are about +1.3VDC.

We'll figure it out. If needed I will replace that board.

If you want to send it back to me, you could also send your sound device and I'll set it up for you.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 06, 2015, 07:02:47 pm

I also thought at first to the converter, but this provides -9V / + 9V to TL072 so it is ok.
Offset master tuning also works up from -1.28V so LM337 it is also ok.


Channel offset triming only works at uppermost position of the 100K pots so pots are ok.
Grain 500Ohm pots are with out any function but measurement was ok.


I think it could be a problem about the input resistance of the TL072, maybe they are out of range with that soundcard. Or what do you think?


I once the soundcard channels measured in operation (white circle wave) X and Y bring 2.26V, RGB, however only 0.68V
with out playing sound all channels have got about 2.26V.


What can I do/test with out oscilloscope?
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 06, 2015, 11:11:45 pm
I think everything is OK.

It just seems like there is a misunderstanding.

The 100K pots are gain. I marked them black.

The 500 ohm pots are offset trim. (Blue).

The effect of the offset trim pots is certainly relative to the overall gain of each channel. Gain is a multiplying factor, so it multiplies the measure of offset.

The offset trim pots are only 500 ohm so they add between zero and 500 ohms to a 15000 ohm resister. They are just there to tweak out the tiniest differences between the channels.

Most of the offset adjustment is in the master negative voltage regulator adjustment.

Since the correction amp is an inverter, waves made in LB are inverted, so it stands to reason that the voltage should drop on the color control signals from the silent offset (measured driectly from the sound card) of some positive voltage to one that is lower and closer to zero when circle.wav is playing. That is correct.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 07, 2015, 02:21:19 pm
LOL
Oh my God! Am I stupid, yes I am.
Something I must have mixed up while reading and translating in my brain.

Now comes power from the amp to the laser.
I made the first attempt in Windows.
The white circle works at 25000Hz. The blanking is not fit. Settings in Laserboy I still need to test. It all seems to be too fast (other test files are still to bad for images/movies) and the scanner is very noisy compared to the SD interface operation.

I have analogous colors !!!

James, many thanks for all the trouble until now.

Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 07, 2015, 02:53:51 pm
In the first test I only have the [TAB> h output wave sample rate.....] is set to 25000. What settings do I have to adjust for a 20k-25k scanner?
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 07, 2015, 06:00:19 pm
The points-per-second rating of scanners is very ambiguous.

It really relates to the point rate of a DAC clocking out the ILDA standard test pattern.

Proprietary laser DACs ususally allow you to change the DAC clock rate.

It doesn't exactly apply to LaserBoy time optimized waves.

That USB sound card DAC you have really only has one fixed rate; 48KHz.

All waves of any sample rate are up or down sampled to 48KHz in the sound driver.

Remember, you are using a sound device. So it is a sound device! It plays waves. You just happen to be sending the signals to a laser projector.

You should set the wave sample rate in LaserBoy to 48000. That is the default.

That means that the sound card will output at its native sample rate.

You control the scanner velocity with settings 3 & 4 in the [Tab] menu.

This is how far the scanners can move in any direction in one sample. Points are relative to signed short integer numbers (16-bits). So the whole cube of defined 3D space is 65535 points in X, Y & Z.

The default settings are probably OK for your scanners.

If you think you are scanning too fast, you can decrease the values for options 3 & 4.

If you think the scanners need more time to settle in the corners of your images, you can also control the dwell time in micro-seconds. (This setting is relative to the fact that your waves are made for some samples-per-second (micro-seconds translates to a number of samples at rate).

Think of it this way... a laser projector is entirely an analog device. It takes ANALOG signals to control it. It doesn't care about DAC clock rates. It only responds to change in voltage over time. You can divide that into samples any way you want.

Centimeters per second... kilometers per hour.... points per sample (1/48000 seconds).... It's all the same thing. :)

Actually, your scanner velocity is measured in radians of rotation per second. And that is relative to the gain setting of your correction amp for X and Y, giving you a maximum scan angle.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 09, 2015, 06:37:41 pm
So I've setup all on raspberry, I still have got magenta blanking Lines. I'm at 5.0V at RGB, juppers do reduce down to 4.85V.


And Colors are very TTL like. Do I have to reduce power on the RGB Channels?
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 09, 2015, 07:58:05 pm
Well, considering the fact that your projector is almost definitely TTL color, you could try dropping down the gain on the color channels to a point where they just come on when they should.

I don't know! :P

Something to think about.... Magenta is an equal mix of red and blue... No green.

That might tell you something.

Your green laser is a DPSS, not a direct injection diode like your blue and red.

Maybe you can get inside of the projector and measure the color control signals that are coming from the internal SD card reader to get an idea of what the projector is designed to respond to.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 10, 2015, 02:59:29 pm


about TTL: it is analog, I can reduce color intensiveness with pot on all RGB channel.


Please take a look at the video (sorry bad phone cam) there you can see the issues:
the whole art will be circled by a white or sometimes magenta copy of it self including the blanking lines.
Some kind of interference on the RGB channels.
 
https://goo.gl/photos/vBoNMaHmtd81P2GS8


If I reduce all RGB channels to 0V, it is still there as you can see:


https://goo.gl/photos/eSFFWDLJ5qvYvWzh9


Have you seen somthing like this before? What can I do?
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 10, 2015, 03:34:39 pm
I've seen enough video of laser display to know that it can look a lot different than the real thing. It's all about the frame rate and exposure time of each frame of the video camera / recorder.

Anyway....

WOW. I don't know.

You could try an experiment.

If you open a LaserBoy wave in Audacity you can play one or two channels in "solo" mode.

So you could plug speakers into channels front left and right and listen to each channel all by itself.

You can then compare the sound to what you hear when you plug the speakers into the color channels and use ALSA Player to play the full 6 or 8 channel wave.

BTW if you set LaserBoy to make 8 channel waves,  there should be total silence in channels 7 & 8, when you play an 8 channel wave.

If you hear anything in those channels then you know that information is getting mixed up in all the channels.

It's weird though.... The color version of the LaserBoy logo that you scanned looks SOOOOO CLOSE!

Good work so far! I know this can be very challenging. I've been through it many times!

You could try lowering the number for option 4 in the [Tab] menu. Then the laser will have more time to trace the blank lines. You can also increase the time for option 5 so the laser dwells longer in the corners and transitions from lit to blank.

What parameters are you using to make waves?

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 11, 2015, 02:24:10 pm

What parameters are you using to make waves?
>>>3,4,5, pots, ... lots, but the white RGB noice do not go away :-(

Even if I swap one of the RGB cannels wire with channel 6 of the DAC there is missing a color in the main picture, but the white RGB noice picture is shown with full colors. So the white noice is on the other non RGB channels also. I do not know what I can do any more.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 11, 2015, 05:55:03 pm
Well, I hate to say this.... but you should probably try the sound card plugged into a Windows machine!

Install the drivers from the disk that came with the sound device.

Install Spider Player.

Set the sound device driver to 8 channels. Go into Windows Sound System settings and set the speaker arrangement to 8 speakers.

See if it works that way.

If it works, the problem is in the configuration of ALSA on the Pi2.

I think we could fix that with a copy of the image that I have here.

We'll figure it out.

Did you make a big red, blue and green circle wave for testing each color channel?

That can be very helpful.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 12, 2015, 07:07:12 am
I've tested all in Windows at the very first try + Spiderplayer + Disc driver + full 8 cannels, also on Linux pc amd64. Always the same white noise. It does not depend on which host I'm running the soundcard + amp + projector. Also I've mad the colored Gears in R/G/B, at that point I've noticed my projektor's RGB channels are twisted (DB25), but that was fixed simple by swaping DAC inputs. I can not get rid of that white noise circling around the picture and the blanking line. The Setup only edits quality of the main picture.


Also I've noticed looping a wave of 10 sec produces a double picture with a small offset, maybe this is also this white noice but on X and Y cannel. Using a one frame wave does make one circled picture.


I think I have no chance to find the source of the white noice. It could be the soundcard, projector..
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 12, 2015, 12:02:56 pm
Have you thought about getting the exact same sound device as I use?

Try getting a USB SND8. It has the C-Media 6206 chip inside and I have never gotten one that did not work. I have made probably more than 30 LaserBoy DACs using this device.

http://www.ebay.com/itm/Sabrent-USB-SND8-8Channel-3D-USB-2-0-Ext-7-1-Surround-Sound-Box-/331237914254?hash=item4d1f51768e

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 12, 2015, 01:02:47 pm

Have you thought about getting the exact same sound device as I use?
>> yes

my soundcard is C8 and has C-Media 6206 chip inside:-(
exact the same, they do not sell, but looks equal:

ADMIN EDIT: LINK REMOVED; reason: way too long! Blowing out the window borders!


*-- SNIP --*

I'm affraid that it is not the soundcard, but what can I do...
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 12, 2015, 07:22:32 pm
Wait a minute!

The sound device you have pictured here: ...

http://laserboy.org/forum/index.php?topic=619.msg6598#msg6598 (http://laserboy.org/forum/index.php?topic=619.msg6598#msg6598)

is not the same as the link you just posted.

The link you just posted looks to be exactly the same kind of device that I have been using and recommending for years.

http://laserboy.org/forum/index.php?topic=8.msg6336#msg6336 (http://laserboy.org/forum/index.php?topic=8.msg6336#msg6336)

Don't get discouraged. You'll figure it out. You KNOW it has to work somehow! :)

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 13, 2015, 12:54:23 pm
is ordered, hope this helps  ;D
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 14, 2015, 01:37:12 am
Well, I bet you know how to test the new sound device when it arrives!

Right now I'm trying to build a new Linux machine.

I've got 2 x 4GB RAM and 4 X 500GB HD. It's an AMD-64 system.

I want to do software RAID 10 (striped mirror) but I can't figure out how to do it with Debian or Xubuntu.

I might have to go with something else like CentOS 7.

I don't know why the sound device you have doesn't work. Maybe it's just a bad design with a lot of cross-talk between the channels.

Something else you might want to know is how to adjust the time delay between the color signals and the galvos.

Galvos take some time to follow the input signals to the galvo amps, so you have to delay the color signal information a bit to let the scanners catch up.

You do this in LaserBoy by shifting the color signal wave samples backwards in time.

The default settings in LaserBoy are 5 samples for 48KHz waves.

If the colors are coming on too soon, you'll see flags, lit lines preceding lit segments. If the colors are coming on too late you'll see tails, following lit segments.

You can adjust the timing for each of the channels of a wave made in LaserBoy.

Go into menu b,option 3. You will see that red, green and blue are set to -5 samples.

LaserBoy can re-shift a wave that you have already made without having to make it all over again. It saves the sample offsets in the header of the wave.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 15, 2015, 02:39:40 am
http://www.prontosystems.org/tux/software_raid


(software raid under debian) page is in german, but translating in google works well.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 15, 2015, 12:28:22 pm
Thanks. I think I got it.

I'm going to use 5 x 500GB HD in a RAID5.

I made a bootable USB stick Xubuntu. So I can go into live mode and do all the mdadm stuff before I install it.

I just ordered a nice video card that can do 4K.

Pretty soon I'm going to get a 65 inch curved screen 4K monitor.

I'll be able to run LaserBoy at 3840 2160 !!! :o

That's just SICK! :)

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 17, 2015, 02:56:05 pm

I'm gonna Ilda editor newly ...


That's still a python script  8)
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 17, 2015, 07:56:23 pm
That's a very interesting methodology you've got there.

Looks good!

Thanks for posting that.

You know you can have your own thread in Laser Software ...

http://laserboy.org/forum/index.php?board=26.0

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 19, 2015, 05:34:36 pm

Yesterday I tried the new soundcard. What can I say. The spirit rotating effect (here magenta) with blanking lines was even stronger, lighter and even faster than with the old sound card. My first thought: I'm going to have to dig deep into my laser projector, the home power supply ... The first thing I was looking for material in the basement, so I can build me a Wire cable between the amp kit and the laser to achieve single DB25 contacts operation. And I have an old printer cable ~ found 5 meters and an old software dongle. Profit after about 1 hour soldering was a 5m DB25 extension cable. (RGB channels are not soldered to test). Now the red gear to the test. goes well, no more issues. The green gear was I think yellow and blue was magenta and had all blanking to lines. But the rotating effect spirit was gone.


Errors were: channel I was exchanged for a color channel, the amp kit directly connected to the projector without shielded cable has interference (ghost Effect) So I think the other 2V + sound card works just as well. To find the bug without oscilloscope is difficult in such a small fast signals. I tested on the Raspberry, today I have connected the correct cables, and for the first time a reasonably clean image (only tested with default settings in Laserboy)


In the python script I will sometimes try to produce music signals, perhaps going yes.


see:


https://goo.gl/photos/8stdcCFv57FkyE9e9 (https://goo.gl/photos/8stdcCFv57FkyE9e9)


 %)
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 21, 2015, 12:27:57 pm
That does look much better!

It looks like you need to slow down the scanner velocity by lowering the number values of options 3 and 4 in the [Tab] menu.

You might also experiment with the sample shifts between the galvo signals and the color signals.

It looks like the lasers are either coming on too soon or too late.

You can really see the effect of scanner to color time alignment if you make a 10 second still image of frame 14; the star field (lots of white dots).

If your timing is off you will see all kinds of streaked lines.

I bet you could figure out a way to make a frame that would tell you whether your scanners are early or late!

Good work, man! :)

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 21, 2015, 06:09:28 pm
Ok, I'll try


-> News about my new beta: see picture, toolbars are ready (hand made, tkinter do not provide by default)  %)
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 21, 2015, 08:47:46 pm
That's pretty cool!

You are welcome to start a new thread in the Laser Software section of this forum.

Did you look at any of the LaserBoy code and see how I made all of the classes that make all of this stuff work?

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 22, 2015, 07:35:03 am
Yes little bit, but python is very diffrent from C/C++.
I've looked a lot in the effects of lb, and in the ilda specifications (pdf) here in the forum.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 22, 2015, 09:36:08 am

Orange is working (ild file from net) converted by lb.


https://goo.gl/photos/2TKubngAymxaEeVG6 (https://goo.gl/photos/2TKubngAymxaEeVG6)


Thank God I've found Laserboy
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 22, 2015, 11:25:27 am
Thank God I've found Laserboy

I think that's the best thing anyone ever said about my work!

I'm really glad you are getting a lot out of LB.

That has been the whole point all along.

When I get my Linux Monster Machine up and running, I will definitely have a Python environment.

I'd love to see what you have there on my own machine, if that's OK with you.

Looks like you have a system that works very well!

Congratulations!

I have an idea of how good it feels to finally see something that is totally what you want and totally under your own control because you understand every part of it.

I knew you could do it! :)

AWESOME JOB.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 22, 2015, 01:55:48 pm
Thank you!
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 22, 2015, 05:01:00 pm
Here you go!

http://laserboy.org/free_art

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 24, 2015, 02:10:33 pm
You're a coder, so I think you'll like every_byte.ild

Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 27, 2015, 03:44:09 am
cool, now I'll build a webif to control the player on raspberry.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 27, 2015, 10:28:37 am
webif for raspberry on default localhost:8100


can you test?


I've got always an single sharp beam in the middle, while changing picture on audacious player
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 28, 2015, 08:14:30 am
OK. I'll try this out as soon as I can.

I'm waiting for the truck to show up with my new 65 inch curved screen LCD 4K monitor!

I got my monster RAID machine set up and working with Xubuntu.

I'll let you know.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on August 28, 2015, 10:13:02 am
Well...........

I now have a 65 inch curved LCD 4K monitor!

I am typing this while looking at 3840 x 2160 pixels!

F**KING STAR TREK and shit!  :)

Things look a little weird at this high of a resolution.


A lot of stuff just wasn't designed with this many pixels in mind.

James.

Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on August 29, 2015, 03:31:44 am
high res times :)
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on September 02, 2015, 03:14:13 pm
new version, fixed "sharp beam issues" while zapping wave files.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on September 02, 2015, 03:20:40 pm
I've found out sadly my laser power supply does only bring TTL/dotted points on low signals ~40%, higher signal is full power, lower signal is off.


Is der a way to build an amp kit to modify a TTL power supply, in order to use as analog?
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on September 02, 2015, 10:24:25 pm
Uh.... I'm not sure I know what you mean.

You can get a laser diode driver that has analog modulation.

But you have to know a bit about laser diodes and how to power them to be able to use one.

If your green lase is TTL, there is probably nothing you can do about it. It is not just a simple diode.

It's diode pumped solid state or DPSS. It's quite a bit more complicated than a regular diode laser.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on September 08, 2015, 05:34:15 am
If I connect the projector with the DB25, it will be set to "Auto mode". From that point no more DMX input is noticed.
Do you think, I can just build in a switch at the 4/17 pin short connection, to set on/off Ilda mode?
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on September 08, 2015, 11:01:21 am
That would be a good guess.

That is the safety interlock switch.

You could also try taking the +5VDC off of pin 13.

That is there to activate (open) a shutter.

Since you have a projector with modulated lasers, you don't have a shutter. But your projector might still  sense that voltage.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on September 08, 2015, 03:04:13 pm
Ah ok, I will test.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on September 12, 2015, 12:59:34 pm
test result: I only need to cut 4/17 pin to stop ilda mode.
I've got a 4 Channel relai for Raspberry for that.
Now I need to implement the gpio switches into py webinterface.


Also I've testet HE Laserscan 6 (win software, free for one projector)
works very well using the Audio DAC. I could run a show using the built in soundcard for mp3, and the DAC.
A complet Lasershow!
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on September 12, 2015, 11:00:11 pm
You should see if there is a way to pipe your stereo audio tracks to channels 7 & 8 on the LaserBoy DAC!


James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on September 13, 2015, 07:54:00 am

Hm, bad idea in my case    ;D , my webinterface for audacious (playing in loop mode) is using amixer "Speakers down/up" command for a smooth change of art with out the sharp white beam during change to new art.  So music will pause, too.


But I thing there is no problem using default audio on pc/raspberry for sound.


I've got the DMX controll program qlc+ (for raspberry or pc(win/linux) and there I've got a timeline, where I can setup external scripts (for example: wget to webif of audacious), or the common dmx commands. If everything is wired up, I can test. But still a lot of work...
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on September 18, 2015, 07:50:26 pm
a laserboy dxf folder import and 3d hidden lines test:


Acad 3d solid->DXB plotter->DXB import & dxf save (acad) ->laserboy->my script->sd card  :o


https://goo.gl/photos/jMc9fprHh7SWMGxo9 (https://goo.gl/photos/jMc9fprHh7SWMGxo9)
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on October 12, 2015, 03:39:06 pm
also works on dreambox sat receiver (mipsel ):
https://goo.gl/photos/hqz4jAjEHRPTg9jm7
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on October 15, 2015, 02:13:00 pm
That's the stuff!

This is why Generic C++ is such a good idea.

It works on almost everything!

Congratulations. You did a great job getting all that together.

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on October 19, 2015, 02:41:57 pm
Hm, C++ would be nice at that point :-D.


As you know I've started a python script to get some experience about the ilda formats.
Then I've found that build in gui "tkinter" included in common python install on pc/raspberry.
So I've build a gui interface to use all the format converters, fixers, displaying ...
Further I've played around with the tkinter's canvas, And now I've got a "AutoCad styled"
ild CAD functionality. But there is one main problem in the gui: I can not zoom in/out. I've tried a lot around.
The main problem is the interface between canvas coords and main window coords. Trying to scale destroys my "magnetic grips" on
start-, end-, points, rubberband previews and the mouse do not match anymore the rigth positions.
The only solution would be to implement some own modules in C++. It would be so awsome, see the pix:
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: James on October 20, 2015, 01:39:16 am
Do you think maybe it has something to do with data types?

The ILDA file format uses signed short integers to store coordinates.

Maybe doing math on signed short integers causes bit rollovers.

I had to write all kinds of math to make LaserBoy work.

I have a class that is a 3D signed short int coordinate and I also have a class that is a 3D float, so I can do math that might result in numbers too big or too small for signed short.

Every time you tap a key, a whole new bitmap is made in memory of the entire display area and copied to the pointer of the visible screen.

All of the math of 3D coordinates and transforms and graphics elements, including the font are in my code.

I don't use any of the graphics stuff in libSDL.

I even wrote my own point plotting and line drawing functions.

I just create a bitmap and copy it to the screen.

That's what makes it generic and that's why it works on almost everything!

James.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on October 22, 2015, 04:26:05 pm
In my case it is because the tkinter Canvas was not made for this. (scalling), but for scrolling.
I need minimum a second db to convert all the coordinates. For mouse events I have to calculate a lot for example "the magnetic grips" on lines. That all need to convert further on zooming. But I'll find a way in python, I've found a cad project based on tkinter python.
Title: Re: I want to build a DAC for Raspberry Pi 2
Post by: emanuel on October 25, 2015, 06:45:49 pm
pixel rendering is cool running very well using tkinter. Fine for animate ilds or previews like this ~140 lines code only:
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