How to get the Microphone (PDM) working with WS2812FX

Hardware Nano Family Nano RP2040 Connect
1

The PDM example alone runs. Also the WS2812FX effects are working well on the RP2040 Connect. But as soon as I want to use both together (for sound/noise based effects) the board does nothing or freezes to a point where i have to flash it with "Blink.ino.elf.uf2".

Is it not possible to read the Microphone data without killing the WS2812 functionality?

#include <Arduino.h>
#include <WS2812FX.h>
#include <PDM.h>

#define LED_COUNT 8
#define LED_PIN 13

WS2812FX ws2812fx = WS2812FX(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);



bool LED_SWITCH = false;
// default number of output channels
static const char channels = 1;
// default PCM output frequency
static const int frequency = 20000;
// Buffer to read samples into, each sample is 16-bits
short sampleBuffer[512];
// Number of audio samples read
volatile int samplesRead;


void onPDMdata() {
  // Query the number of available bytes
  int bytesAvailable = PDM.available();

  // Read into the sample buffer
  PDM.read(sampleBuffer, bytesAvailable);

  // 16-bit, 2 bytes per sample
  samplesRead = bytesAvailable / 2;
}

void audioservice(){

 if (samplesRead) {

    // Print samples to the serial monitor or plotter
    for (int i = 0; i < samplesRead; i++) {
      if (channels == 2) {
        Serial.print("L:");
        Serial.print(sampleBuffer[i]);
        Serial.print(" R:");
        i++;
      }
      Serial.println(sampleBuffer[i]);

      if (sampleBuffer[i] > 10000 || sampleBuffer[i] <= -10000) {
        LED_SWITCH = !LED_SWITCH;
        if (LED_SWITCH) {
          Serial.println();
          Serial.println("ON!");
          Serial.println();
          delay(1000);
        }
        else {
          Serial.println();
          Serial.println("OFF!");
          Serial.println();
          delay(1000);
        }
      }
    }

    // Clear the read count
    samplesRead = 0;
  }
}


void setup() {


  Serial.begin(9600);
  while (!Serial);
  sleep_ms(1000);
  Serial.println("Setup");

  // PDM.onReceive(onPDMdata);
  // // Configure the data receive callback
  // if (!PDM.begin(channels, frequency)) {
  //   Serial.println("Failed to start PDM!"); 
  // }

  ws2812fx.init();
  ws2812fx.setBrightness(100);
  ws2812fx.setSpeed(2000);
  ws2812fx.setMode(FX_MODE_RAINBOW_CYCLE);
  ws2812fx.start();

}

unsigned long lastTime = 0;
unsigned long timer = 0;

void loop() {
  ws2812fx.service();
  //audioservice();
}
2

The board is always doing exactly what you told it to do. I can see two "delay(1000);" where you are telling the board to "do nothing"... you also have a "for" loop, disallowing any activity outside that loop. Did you write this, or ChatGPT?

Look for "arduino blink without delay" and "arduino several things happening" Programming Electronics Academy did these well.

3

its from the official PDM example. if you clap your hands the board pauses for 1 second. otherwise it prints out the audio wave. (if the WS2812FX is not enabled)

4

I am guessing... WSFX did not expect (or program for) any other devices needing service (blocking code). Try writing your own wsfx? It wont take long to learn.

5

I tried to read the data during the loop(), instead of using the callback function.

// query the number of bytes available
int bytesAvailable = PDM.available();
// read into the sample buffer
PDM.read(sampleBuffer, bytesAvailable);

but ws2812fx still did not work.

6

With the help of this thread I got it working:

platformio.ini:

[env:nanorp2040Pico]
platform = https://github.com/maxgerhardt/platform-raspberrypi.git
board = nanorp2040connect
framework = arduino
board_build.core = earlephilhower
lib_deps = kitesurfer1404/WS2812FX@^1.4.2

Just put the Audio stuff on one core and the LED stuff on the other:

void setup1(){

  while (!Serial);
  sleep_ms(1000);
  Serial.println("Setup1");

  ws2812fx.init();
  ws2812fx.setBrightness(100);
  ws2812fx.setSpeed(2000);
  ws2812fx.setMode(FX_MODE_RAINBOW_CYCLE);
  ws2812fx.start();
}

void loop1(){
  //sleep_ms(1000);
  //Serial.println("loop1");
  ws2812fx.service();
}
7

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