esp32 non-standard i2c pins

[zerog2k]

is there a way to init esp32 for non standard i2c pins? I have a dev board with ssd1306 i2c hardwired to pins 4,5 (scl, sda). I didn't see a way to override this during init, e.g. w/ ssd1306_128x64_i2c_init() I could fix it by hacking directly on ssd1306_i2c_common.c, but wonder if there is a better way?

[zerog2k]

i see this note in ssd1306_128x64.h about calling ssd1306_i2cInitEx() directly:

/**
 * @brief Inits 128x64 OLED display over i2c (based on SSD1306 controller).
 *
 * Inits 128x64 OLED display over i2c (based on SSD1306 controller)
 * This function uses hardcoded pins for i2c communication, depending on your hardware.
 * If you use non-standard pins in your project, please perform call ssd1306_i2cInitEx() and
 * ssd1306_128x64_init().
 */
void         ssd1306_128x64_i2c_init();

however, ssd1306_i2cInitEx() doesn't seem to be in scope/defined if I just include "ssd1306.h". Do I need to include other stuff to use custom i2c pins?

[zerog2k]

ok got it to work with this:

#include "ssd1306.h"
#include "i2c/ssd1306_i2c.h"
#define SCL_PIN     4
#define SDA_PIN     5

and in setup():

    ssd1306_i2cInitEx(SCL_PIN, SDA_PIN, SSD1306_SA);
    ssd1306_128x64_init();

would be awsome to have a custom init function as a first-class citizen, e.g. ssd1306_128x64_i2c_init_custom(int8_t scl, int8_t sda)

[lexus2k]

Hi,

Good idea. There is one moment: not all i2c implementations allow to change sda/scl pins. Some of i2c implementations have other options: for Linux, this is the number of i2c bus. Actually, I added ssd1306_i2cInitEx, because my first esp8266-01 module has only non-standard 2 pins. I will add new function, initialization in 2 steps confuses many developers.

[lexus2k]

Could you please confirm that ssd1306_128x64_i2c_initEx() is what you expect to see in the library?

[zerog2k]

what would the function signature be of ssd1306_128x64_i2c_initEx(), and would it be a replacement to ssd1306_128x64_init(), or just a call we need to make before it?

[lexus2k]

void ssd1306_128x64_i2c_initEx(int8_t scl, int8_t sda, int8_t sa);

[zerog2k]

thanks! yes with latest lib version (1.4.11) this is working good for me: ssd1306_128x64_i2c_initEx(SCL_PIN, SDA_PIN, SSD1306_SA);