First encounter with ESP32

April 2, 2018

I had some issues working with the ESP32. I will list all the issues I had and their solutions. For the record I use Manjaro 17.1.7 - 64bits.

ESP32 uses python scripts to configure, compile and flash the chip. If the scripts don’t work it’s most likely due to python3 is the default application for the executable python. I should be python 2.7.

$ python --version
Python 2.7.14

Fail to write to “serial port” /dev/ttyUSB0 using python. The problem is the library serial. When importing the library in python

import serial

You should have installed pyserial instead of serial.

$ pip install pyserial

Add your $USER to uupc group in order to have permission to write through /dev/ttyUSB0. In arch linux:

$ usermod -a -G uucp $USER

Assign not enough stack memory to a task when using FreeRTOS. Check configMINIMAL_STACK_SIZE in the ESP32 documentation.

// For ESP-IDF applications
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"

BaseType_t xTaskCreate( 
        TaskFunction_t pvTaskCode, 
        const char * const pcName, 
        unsigned short usStackDepth, 
        void *pvParameters, 
        UBaseType_t uxPriority, 
        TaskHandle_t *pxCreatedTask 
    );

Use main instead of app_main

// Wrong
int main(){
    ...
}

// Correct
void app_main(){
    ...
}

Forget initialize the flash. Quoted from “Explore Embedded”, the ESP32 Modules run code from an external flash. Unless you’re using directly the ESP32 chip, the module/board maker will taker of the flash initialization and access. link

void app_main(){
    ESP_ERROR_CHECK( nvs_flash_init() );
    ...
}

Use vTaskStartScheduler();. vTaskStartScheduler() call is not required, as scheduler is already started before app_main() call

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First encounter with ESP32

Toolchain related

Library related