ESP32 GATEWAY - Wire.h library malfunction

[erphillips28]

Im getting errors regarding SDA and SCL when trying to #include <Wire.h> library.
-> I am using Arduino IDE
-> I am using Olimex ESP32 Gateway board

Heres the code

Code Select Expand

#include <Wire.h>

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:


Heres the error

Arduino: 1.8.5 (Mac OS X), Board: "OLIMEX ESP32-GATEWAY, 80MHz, 115200"

/Users/eruss28/Documents/Arduino/hardware/espressif/esp32/libraries/Wire/src/Wire.cpp: In member function 'void TwoWire::begin(int, int, uint32_t)':
/Users/eruss28/Documents/Arduino/hardware/espressif/esp32/libraries/Wire/src/Wire.cpp:51:34: error: 'SDA' was not declared in this scope
             if(sda==-1) sdaPin = SDA; //use Default Pin
                                  ^
/Users/eruss28/Documents/Arduino/hardware/espressif/esp32/libraries/Wire/src/Wire.cpp:63:34: error: 'SCL' was not declared in this scope
             if(scl==-1) sclPin = SCL; // use Default pin
                                  ^
exit status 1
Error compiling for board OLIMEX ESP32-GATEWAY.

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Curious if I can use a #define somewhere in the code to define pins on the Gateway as SCL and SDA, or if I have to rewrite part of the library itself.

Thanks for the help!

[Stanimir5F]

Hello erphillips28!

I managed to replicate the problem and figured out what cause it. Although I'm not sure I can give you an appropriate suggestion how to solve it. From what I can see it's the issue that in the GATEWAY variant of the Espressif package SCL and SDA are not defined. For example on the ESP32-EVB there is such definitions:

#ifndef Pins_Arduino_h
#define Pins_Arduino_h

#include <stdint.h>

#define EXTERNAL_NUM_INTERRUPTS 16
#define NUM_DIGITAL_PINS        40
#define NUM_ANALOG_INPUTS       16

#define analogInputToDigitalPin(p)  (((p)<20)?(esp32_adc2gpio[(p)]):-1)
#define digitalPinToInterrupt(p)    (((p)<40)?(p):-1)
#define digitalPinHasPWM(p)         (p < 34)


static const uint8_t KEY_BUILTIN = 34;

static const uint8_t TX = 1;
static const uint8_t RX = 3;

static const uint8_t SDA = 13;
static const uint8_t SCL = 16;

static const uint8_t SS    = 17;
static const uint8_t MOSI  = 2;
static const uint8_t MISO  = 15;
static const uint8_t SCK   = 14;

#define BOARD_HAS_1BIT_SDMMC

#endif /* Pins_Arduino_h */

And thus on ESP32-EVB I2C module works.

The problem is on ESP32-GATEWAY you can't simply add them in the "pins_aruino.h" file and expect to work. It's because the I2C functions have to be mapped somehow to certain pins and then you can add them into the variant file.

Stan, Olimex

[LubOlimex]

I2C pins for the GATEWAY were added 3 days ago.

Check here: https://github.com/espressif/arduino-esp32/pull/1436