r2r sink

[parabyte]

is there any any examples on how to use audiotools with a crude 8bit r2r dac on a arduino on a stm32?

[pschatzmann]

No, I think the quality would be too bad.
You can try to use the internal Dac or Pwm instead.

What Micocontroller do you plan to use?

[parabyte]

stm32 blackpill F4 variant, i got your snapclient working on it with ethernet,

[pschatzmann]

As far as I know, the blackpill does not have any DAC, but you can still use PWM which should give a better audio quality then your 8 step r2r.

ps. I2S should work as well...

[parabyte]

sadly the above code as is throws this error.

/tmp/.arduinoIDE-unsaved2024723-28154-1voj54y.090d/sketch_aug23f/sketch_aug23f.ino:7:1: error: 'PWMAudioStream' does not name a type
7 | // put your main code here, to run repeatedly:
| ^ ~~~~~~~~~~~~
/tmp/.arduinoIDE-unsaved2024723-28154-1voj54y.090d/sketch_aug23f/sketch_aug23f.ino:8:19: error: 'pwm' was not declared in this scope
8 |
| ^
/tmp/.arduinoIDE-unsaved2024723-28154-1voj54y.090d/sketch_aug23f/sketch_aug23f.ino: In function 'void setup()':
/tmp/.arduinoIDE-unsaved2024723-28154-1voj54y.090d/sketch_aug23f/sketch_aug23f.ino:18:17: error: 'pwm' was not declared in this scope

exit status 1

Compilation error: 'PWMAudioStream' does not name a type

[parabyte]

any chance of any pointers to do this r2r dac thing even though its a bad idea, i spent a day populating a vero board with resistors with my daughter and just want to show it off doing something useful, :)

[pschatzmann]

This should be quite easy to implement: Define your own output class or use a CallbackStream and define the write callback.

Write the data into a buffer and output the data with an AudioTimer: There you just map the input values to your pins.

If your input provides stereo data you need to convert it to mono first or you need to use a second ladder.

I can't reproduce your issue with the PWMAudioStream: what Board Part Number did you select ? I tried with Blackpill401CC, Blackpill401CE and Blackpill411CE. For some I needed to uncomment the USE_I2S in AudioConfig.h

[pschatzmann]

I have added a DRAFT implementation: I let you test and debug it...

[parabyte]

i seem to be hitting this error

/home/gatekeeper/Arduino/libraries/stm32-i2s/src/stm32-i2s.h:131:20: error: 'STM_I2S_PINS' was not declared in this scope
131 | I2SPin pins[5] = STM_I2S_PINS;
| ^~~~~~~~~~~~
/home/gatekeeper/Arduino/libraries/stm32-i2s/src/stm32-i2s.h: In member function 'void stm32_i2s::Stm32I2sClass::MX_I2S3_Init()':
/home/gatekeeper/Arduino/libraries/stm32-i2s/src/stm32-i2s.h:481:22: error: 'SPI_INSTANCE_FOR_I2S' was not declared in this scope
481 | hi2s3.Instance = SPI_INSTANCE_FOR_I2S;

[parabyte]

its building fine if i disable i2s following the discussion we had pschatzmann/arduino-snapclient#34

[parabyte]

an example of how you would do r2r in a sketch would be fantastic

[pschatzmann]

It's basically like any other output class: The only special thing you need to do is to define the channel1_pins in the configuration for mono or channel1_pins and channel2_pins for stereo.

It's up to you how many pins you want to use...

  // start 
  auto config = out.defaultConfig();
  config.copyFrom(info); 
  config.channel1_pins = {10,11,12,13,14,15,16,17};
  if (!out.begin(config)){
    Serial.println("error");
    while(true);
  }

I am not sure about the max sample rate that will work since this is limited by the speed of digitalWrite()

[parabyte]

i cant seem to get sound output from the snapclient into this new lovely lib you written, ?

[pschatzmann]

You need to do some proper testing with some simple test sketches first:

1. check the mapping of the input values (range for 16 bits: −32,768 to +32,767) to output values (range for 8 bits: 0—255)
2. check the activated pins for all output values
3. check the generated voltage for the full output value range

After you confirmed that the voltages are right you can start with a sine test case and a min sample rate of 8000 and increase the sample rate to determine the max supported rate

[parabyte]

just ordered a oscilloscope so i can give you some meaningful measurements

[parabyte]

iv just crudely measured with my multimeter. and all seems well, from what i can hear and measure crudely with my multimeter this is producing tones and working fine with the various tests you suggested.

[pschatzmann]

So, if you connect the DAC to some earphones and use the sine test output sketch;
What is the max sample rate that still works ?

[parabyte]

on my particular blackpill board its maxing out at 10000 unless i am mistaken

…

On Wed, Aug 28, 2024 at 3:27 AM Phil Schatzmann ***@***.***> wrote: So, if you connect the DAC to some earphones and use the sine test output sketch; What is the max sample rate that still works ? — Reply to this email directly, view it on GitHub <#1675 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACDX5W63DXN3SRB52J7MEX3ZTUYR3AVCNFSM6AAAAABNAG5IHGVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTANBWHE2DCNQ> . You are receiving this because you authored the thread.Message ID: <pschatzmann/arduino-audio-tools/repo-discussions/1675/comments/10469416@ github.com>

[parabyte]

mine is cc variant

[parabyte]

audio-tools now has a r2r driver!

thanks!