I2C0 works but I2C1 doesn't

[w9ran]

Here is a simple test program to check out .96" oled displays. If I connect the display to GPIO 16/17 and enable I2C0, it works. But if I move the display to GPIO 18/19 and enable I2C1, the display remains blank. I've tried other legal I2C1 pin combinations with the same result - I2C0 always works and I2C1 never works. I can't see where I'm doing anything wrong so really would appreciate any suggestions, thanks.

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define SCREEN_ADDRESS 0x3C ///< See datasheet for Address; 0x3C

// I2C pins are defined in Raspberry Pi Pico pins-arduino.h file for mbed

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

void setup() {
// i2c works
// Wire.setSDA(16);
// Wire.setSCL(17);
// Wire.begin();

// i2c1 does not work
Wire1.setSDA(18);
Wire1.setSCL(19);
Wire1.begin();
display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS); // initialize display
// Clear the buffer
display.clearDisplay();
display.setTextSize(2); // Normal 1:1 pixel scale
display.setTextColor(SSD1306_WHITE); // Draw white text
display.setCursor(20,30);
display.println("I2C TEST");
display.display();
}
void loop() {
}

[earlephilhower]

I'm not seeing your code tell the display library to use Wire1 and not Wire, so check if there's a constructor or begin method to allow that.

[Andy2No]

Yep. It looks like this line would need to be changed, to use Wire1 instead:

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

Try changing &Wire to &Wire1.

[w9ran]

Thank you! That never occurred to me, but now I know the proper usage.