ESP32 Forum

Posted: **Thu Dec 09, 2021 2:40 pm**

Hi,

I am for a pretty long time stuck with trying to get a can driver working. So first some basic information of my setup.

Hardware: ESP32-Wroom
API: ESP-IDF 4.3
Platform: VScode with PlatformIO (also used the espressif plugin, but same problem)

So i used the most simple example code to send somthing to the can driver. I used the TWAI example stated on the site. I only made it so that it send a message every second.

Code: [Select all] [Expand/Collapse]

#include <stdio.h>
#include <stdlib.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_err.h"
#include "esp_log.h"
#include "driver/gpio.h"
#include "driver/twai.h"
#include "esp_rom_gpio.h"
#include "esp_rom_sys.h"
 
/* --------------------- Definitions and static variables ------------------ */
//Example Configuration
#define TX_GPIO_NUM                     5
#define RX_GPIO_NUM                     4
 
 
static void can_setup(void)
{
    //Initialize configuration structures using macro initializers
    twai_general_config_t g_config = TWAI_GENERAL_CONFIG_DEFAULT(TX_GPIO_NUM, RX_GPIO_NUM, TWAI_MODE_NORMAL);
    twai_timing_config_t t_config = TWAI_TIMING_CONFIG_25KBITS();
    twai_filter_config_t f_config = TWAI_FILTER_CONFIG_ACCEPT_ALL();
 
    //Install TWAI driver
    if (twai_driver_install(&g_config, &t_config, &f_config) == ESP_OK) {
        printf("Driver installed\n");
    } else {
        printf("Failed to install driver\n");
        return;
    }
 
    //Start TWAI driver
    if (twai_start() == ESP_OK) {
        printf("Driver started\n");
    } else {
        printf("Failed to start driver\n");
        return;
    }
 
}
 
void app_main(void)
{
    can_setup();
    
    while(1)
    {
        //Configure message to transmit
        twai_message_t message;
        message.identifier = 0xAAAA;
        message.extd = 1;
        message.data_length_code = 4;
        for (int i = 0; i < 4; i++) {
            message.data[i] = 0;
        }
 
        //Queue message for transmission
        if (twai_transmit(&message, pdMS_TO_TICKS(1000)) == ESP_OK) {
            printf("Message queued for transmission\n");
        } else {
            printf("Failed to queue message for transmission\n");
        }
        vTaskDelay(1000 / portTICK_RATE_MS);
    }
}

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ouput

Code: [Select all] [Expand/Collapse]

Driver installed
Driver started
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Message queued for transmission
Failed to queue message for transmission
Failed to queue message for transmission
Failed to queue message for transmission
Failed to queue message for transmission

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after this there is a endless loop of failed messages

Problem
First i checked if any message is after the can driver side, but any message is to be found. So used a logic analyzer to see if there happens something on the pin itself. I discovered that only a small pulse of 40 μs is send on the TX pin but that's it. but anything like a normal message. As you can see it fails to send a message after a few are completed. There are also no pulses detected anymore.

Already checked the logic analyzer, but it works fine. so i dont have any idea anymore where the problem lies. any suggestions?

Posted: **Wed Feb 23, 2022 8:33 am**

I have also encountered this problem. I have checked it for a long time and think it is the official CAN function that is not supported.

Posted: **Wed Feb 23, 2022 12:05 pm**

Might be something wrong with the driver's GPIO configuration. Have you tried using another set of GPIOs?

ESP32 Forum

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