Earle F. Philhower, III
07500e89db
Rewrite the I2S code from scratch to eliminate the dependence on the pico-extras implementation and to support I2S input as well. 8-bit, 16-bit, 24-bit, and 32-bit words are supported. Multiple I2S ports are allowed (theoretically up to 6 because 2 DMA channels are required per port). I2S input and I2S output are supported. Add input example Fixes #535 Fixes #99 Fixes #562
71 lines
1.8 KiB
Arduino
71 lines
1.8 KiB
Arduino
/*
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This example generates a square wave based tone at a specified frequency
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and sample rate. Then outputs the data using the I2S interface to a
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MAX08357 I2S Amp Breakout board.
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created 17 November 2016
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by Sandeep Mistry
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modified for RP2040 by Earle F. Philhower, III <earlephilhower@yahoo.com>
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bool setBCLK(pin_size_t pin);
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- This assigns two adjacent pins - the pin after this one (one greater)
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is the WS (word select) signal, which toggles before the sample for
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each channel is sent
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bool setDATA(pin_size_t pin);
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- Sets the DOUT pin, can be any valid GPIO pin
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*/
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#include <I2S.h>
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// Create the I2S port using a PIO state machine
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I2S i2s(OUTPUT);
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// GPIO pin numbers
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#define pBCLK 20
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#define pWS (pBCLK+1)
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#define pDOUT 22
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const int frequency = 440; // frequency of square wave in Hz
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const int amplitude = 500; // amplitude of square wave
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const int sampleRate = 16000; // minimum for UDA1334A
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const int halfWavelength = (sampleRate / frequency); // half wavelength of square wave
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int16_t sample = amplitude; // current sample value
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int count = 0;
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void setup() {
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pinMode(LED_BUILTIN, OUTPUT);
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digitalWrite(LED_BUILTIN, 1);
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Serial.begin(115200);
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Serial.println("I2S simple tone");
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i2s.setBCLK(pBCLK);
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i2s.setDATA(pDOUT);
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i2s.setBitsPerSample(16);
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// start I2S at the sample rate with 16-bits per sample
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if (!i2s.begin(sampleRate)) {
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Serial.println("Failed to initialize I2S!");
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while (1); // do nothing
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}
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}
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void loop() {
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if (count % halfWavelength == 0) {
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// invert the sample every half wavelength count multiple to generate square wave
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sample = -1 * sample;
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}
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// write the same sample twice, once for left and once for the right channel
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i2s.write(sample);
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i2s.write(sample);
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// increment the counter for the next sample
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count++;
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}
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