Teensy 3.5 - DAC questions.

[GwakSeongJong]

Teensy 3.5 - DAC questions.

Good morning. nice to meet you.

I'm curious as to how to do the DAC output.
What if I want to output DAC with coding? Thank you for your library or command.

 

[GremlinWrangler]

See 12 bit analog output on here for commands to directly drive it (use A21 and A22 for T3.5)
https://www.pjrc.com/teensy/teensy31.html
Or you can use the audio library
https://www.pjrc.com/teensy/td_libs_Audio.html
either directly or have a look at the source

 

[defragster]

Best guess - it may help to understand or get started and ask the next question?

There is a STICKY 'Wiki Coming' thread - I went to that thread and searched DAC: Wiki-Coming-Please-link-worthy-posts

That post links to this - reading a few posts you should find you answer : analogWrite(A14,sine_data[t]);

Excepting you'd use A21 or A22 for a DAC pin on T_3.5

 

[GwakSeongJong]

about Teensy 3.5//
void setup() {
analogWriteResolution(12);
}

void loop() {
int val = function();

analogWrite(A21, (int)val);

}

int function(){

...........
...........

return ref;
}


Right? Is this the correct code method?

I want to get an analog value that keeps the voltage constant, not the audio output.

 

[jwatte]

Is there a simple wrapper to feed the DAC using DMA? I assume this is what the audio library does internally.

Also, is there now a USB mode that lets the Teensy look like a USB audio output class device? That would be spiffy!

(While I have the wish list open: a USB audio output class device and a serial port for SerialUSB in a single composite device would be fantastic.)

 

[jwatte]

And, yes, there is Serial + MIDI + Audio as an option! That is, in fact, fantastic! (And the audio design tool generates the framework of using Teensy as a USB output device, which is nice, too.)

I haven't been able to find any documentation for how to use the different USB modes, though. Is there a page I'm missing?

Like, if I choose for example the "MTP disk" USB mode, or the "Keyboard + Touch Screen" mode, is there documentation for what functions I should be using out of Teensyduino to go with these endpoints? Or do I just read the code and figure it out for myself?
Some of the features (serial, keyboard, etc) are documented in the Teensyduino libs section: https://www.pjrc.com/teensy/td_keyboard.html
MTP Disk, Touchscreen, Audio, and MIDI are not, however.