Is it possible, to use the SparkFun Pro Micro - RP2040 as slave with the I2C protocol? According to the RP2040 datasheet (https://datasheets.raspberrypi.com/rp20 … asheet.pdf) the microcontroller can be used as slave (see “4.3.1. Features”).
With the right code, I don’t see any reason why you couldn’t.
So, what is the right code?
I don’t have any, you’d need to write your own.
Yes, it can be. I have been using various examples for arduino IC2 coms for master/slave (search for it on your browser of choice) and it works on the regular qwiic connector just fine. I cannot, however, get to work using Wire1 on the second I2C port that is supposed to be available on RP2040 devices.
Anyway, this is what have been using for a simple test, modified examples from various sources:
Sending MCU Code:
int x = 0;
void setup() {
// Start the I2C Bus as Master
Wire.begin();
}
void loop() {
Wire.beginTransmission(9); // transmit to device #9
Wire.write(x); // sends x
Wire.endTransmission(); // stop transmitting
x++; // Increment x
if (x > 5) x = 0; // `reset x once it gets 6
delay(500);
}
Receiving MCU Code:
#include <Wire.h>
#include <Adafruit_NeoPixel.h>
#ifdef AVR
#include <avr/power.h> // Required for 16 MHz Adafruit Trinket
#endif
// Which pin on the Arduino is connected to the NeoPixels?
// On a Trinket or Gemma we suggest changing this to 1:
#define LED_PIN 25
// How many NeoPixels are attached to the Arduino?
#define LED_COUNT 1
// Declare our NeoPixel strip object:
Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
// Argument 1 = Number of pixels in NeoPixel strip
// Argument 2 = Arduino pin number (most are valid)
// Argument 3 = Pixel type flags, add together as needed:
// NEO_KHZ800 800 KHz bitstream (most NeoPixel products w/WS2812 LEDs)
// NEO_KHZ400 400 KHz (classic ‘v1’ (not v2) FLORA pixels, WS2811 drivers)
// NEO_GRB Pixels are wired for GRB bitstream (most NeoPixel products)
// NEO_RGB Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)
// NEO_RGBW Pixels are wired for RGBW bitstream (NeoPixel RGBW products)
// setup() function – runs once at startup --------------------------------
int x = 0;
void setup() {
// These lines are specifically to support the Adafruit Trinket 5V 16 MHz.
// Any other board, you can remove this part (but no harm leaving it):
Serial.begin(9600);
strip.begin(); // INITIALIZE NeoPixel strip object (REQUIRED)
strip.show(); // Turn OFF all pixels ASAP
strip.setBrightness(50); // Set BRIGHTNESS to about 1/5 (max = 255)
Wire.begin(9);
// Attach a function to trigger when something is received.
Wire.onReceive(receiveEvent);
}
void receiveEvent(int bytes) {
x = Wire.read(); // read one character from the I2C
}
// loop() function – runs repeatedly as long as board is on ---------------
void loop() {
if (x == 1) {
strip.setPixelColor(0,255,0,0); // Set pixel’s color (in RAM) RED
strip.show();
// Fill along the length of the strip in various colors…
// colorWipe(strip.Color(255, 0, 0), 2000); // Red
// colorWipe(strip.Color( 0, 255, 0), 2000); // Green
// colorWipe(strip.Color( 0, 0, 255), 2000); // Blue
}
// Do a theater marquee effect in various colors…
// theaterChase(strip.Color(127, 127, 127), 100); // White, half brightness
// theaterChase(strip.Color(127, 0, 0), 100); // Red, half brightness
// theaterChase(strip.Color( 0, 0, 127), 100); // Blue, half brightness
if (x == 3) {
strip.setPixelColor(0,0,255,0); // Set pixel’s color (in RAM) GREEN
strip.show();
// rainbow(50); // Flowing rainbow cycle along the whole strip
// theaterChaseRainbow(50); // Rainbow-enhanced theaterChase variant
}
}
// Some functions of our own for creating animated effects -----------------
// Fill strip pixels one after another with a color. Strip is NOT cleared
// first; anything there will be covered pixel by pixel. Pass in color
// (as a single ‘packed’ 32-bit value, which you can get by calling
// strip.Color(red, green, blue) as shown in the loop() function above),
// and a delay time (in milliseconds) between pixels.
void colorWipe(uint32_t color, int wait) {
for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip…
strip.setPixelColor(i, color); // Set pixel’s color (in RAM)
strip.show(); // Update strip to match
delay(wait); // Pause for a moment
}
}
// Theater-marquee-style chasing lights. Pass in a color (32-bit value,
// a la strip.Color(r,g,b) as mentioned above), and a delay time (in ms)
// between frames.
void theaterChase(uint32_t color, int wait) {
for(int a=0; a<10; a++) { // Repeat 10 times…
for(int b=0; b<3; b++) { // ‘b’ counts from 0 to 2…
strip.clear(); // Set all pixels in RAM to 0 (off)
// ‘c’ counts up from ‘b’ to end of strip in steps of 3…
for(int c=b; c<strip.numPixels(); c += 3) {
strip.setPixelColor(c, color); // Set pixel ‘c’ to value ‘color’
}
strip.show(); // Update strip with new contents
delay(wait); // Pause for a moment
}
}
}
// Rainbow cycle along whole strip. Pass delay time (in ms) between frames.
void rainbow(int wait) {
// Hue of first pixel runs 5 complete loops through the color wheel.
// Color wheel has a range of 65536 but it’s OK if we roll over, so
// just count from 0 to 5*65536. Adding 256 to firstPixelHue each time
// means we’ll make 5*65536/256 = 1280 passes through this outer loop:
for(long firstPixelHue = 0; firstPixelHue < 5*65536; firstPixelHue += 256) {
for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip…
// Offset pixel hue by an amount to make one full revolution of the
// color wheel (range of 65536) along the length of the strip
// (strip.numPixels() steps):
int pixelHue = firstPixelHue + (i * 65536L / strip.numPixels());
// strip.ColorHSV() can take 1 or 3 arguments: a hue (0 to 65535) or
// optionally add saturation and value (brightness) (each 0 to 255).
// Here we’re using just the single-argument hue variant. The result
// is passed through strip.gamma32() to provide ‘truer’ colors
// before assigning to each pixel:
strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(pixelHue)));
}
strip.show(); // Update strip with new contents
delay(wait); // Pause for a moment
}
}
// Rainbow-enhanced theater marquee. Pass delay time (in ms) between frames.
void theaterChaseRainbow(int wait) {
int firstPixelHue = 0; // First pixel starts at red (hue 0)
for(int a=0; a<30; a++) { // Repeat 30 times…
for(int b=0; b<3; b++) { // ‘b’ counts from 0 to 2…
strip.clear(); // Set all pixels in RAM to 0 (off)
// ‘c’ counts up from ‘b’ to end of strip in increments of 3…
for(int c=b; c<strip.numPixels(); c += 3) {
// hue of pixel ‘c’ is offset by an amount to make one full
// revolution of the color wheel (range 65536) along the length
// of the strip (strip.numPixels() steps):
int hue = firstPixelHue + c * 65536L / strip.numPixels();
uint32_t color = strip.gamma32(strip.ColorHSV(hue)); // hue → RGB
strip.setPixelColor(c, color); // Set pixel ‘c’ to value ‘color’
}
strip.show(); // Update strip with new contents
delay(wait); // Pause for a moment
firstPixelHue += 65536 / 90; // One cycle of color wheel over 90 frames
}
}
}