I tested this today. It seems to work fine.
To test, I used 4 PWM pins and with 10K resistors and 0.1 uF capacitors to as low-pass filters, to create 4 distinctive test waveforms. I connected those 4 waveforms to the 4 inputs on 2 audio shields. Then I ran a modified copy (to turn on the PWM) of the PassThroughQuad example.
Here's the hardware setup:
This is what my oscilloscope sees for the 4 outputs:
It seems to be working as intended. You can see the frequencies and duty cycles of each waveform matches the code below. You can also see the first 2 PWM signals appear on outputs 3 & 4, because that pass through example routes the stereo audio from one shield's inputs to the others outputs and vise versa.
This is the exact code I ran on the Teensy 4.1 for this test:
Code:
#include <Audio.h>
AudioInputI2SQuad i2s_quad1; //xy=150,69
AudioOutputI2SQuad i2s_quad2; //xy=365,94
AudioConnection patchCord1(i2s_quad1, 0, i2s_quad2, 2);
AudioConnection patchCord2(i2s_quad1, 1, i2s_quad2, 3);
AudioConnection patchCord3(i2s_quad1, 2, i2s_quad2, 0);
AudioConnection patchCord4(i2s_quad1, 3, i2s_quad2, 1);
AudioControlSGTL5000 sgtl5000_1; //xy=302,184
AudioControlSGTL5000 sgtl5000_2; //xy=302,254
void setup() {
// create 4 test waveforms and distinct frequencies
analogWriteFrequency(28, 440);
analogWriteFrequency(33, 530);
analogWriteFrequency(36, 610);
analogWriteFrequency(37, 610);
analogWrite(28, 128);
analogWrite(33, 128);
analogWrite(36, 64);
analogWrite(37, 190);
AudioMemory(12);
// Enable the first audio shield, select input, and enable output
sgtl5000_1.setAddress(LOW);
sgtl5000_1.enable();
sgtl5000_1.inputSelect(AUDIO_INPUT_LINEIN);
sgtl5000_1.volume(0.5);
// Enable the second audio shield, select input, and enable output
sgtl5000_2.setAddress(HIGH);
sgtl5000_2.enable();
sgtl5000_2.inputSelect(AUDIO_INPUT_LINEIN);
sgtl5000_2.volume(0.5);
}
void loop() {
}
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Originally Posted by PaulS
