Uart2 does not work.

[readingmb]

Hello !!
uart 2 does not work !!!
I am very urgent.
The code is written as follows:

Code: Select all

  uart_port_t uart_num = UART_NUM_2;                                     //uart port number
  uart_config_t uart_config = {
      .baud_rate = 115200,                    //baudrate
      .data_bits = UART_DATA_8_BITS,          //data bit mode
      .parity = UART_PARITY_DISABLE,          //parity mode
      .stop_bits = UART_STOP_BITS_1,          //stop bit mode
      .flow_ctrl = UART_HW_FLOWCTRL_DISABLE,  //hardware flow control(cts/rts)
      .rx_flow_ctrl_thresh = 122,             //flow control threshold
  };
  ESP_LOGI(TAG, "Setting UART configuration number %d...", uart_num);
  ESP_ERROR_CHECK( uart_param_config(uart_num, &uart_config));
  QueueHandle_t uart_queue;
  ESP_ERROR_CHECK( uart_set_pin(uart_num, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE));
  ESP_ERROR_CHECK( uart_driver_install(uart_num, 1024 * 2, 1024 * 2, 10, UART_INTR_NUM, &uart_queue));

  char* test_str = "This is a test string.\n";
  uart_tx_chars(uart_num, (const char*)test_str,strlen(test_str));
  printf("ESP32 uart Send\n");
  while(1);

The result screen is as follows.
However, it does not work.
I have measured it with an oscilloscope, but there is no signal.
I hope you solve it.

Code: Select all

rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0x00
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:2
load:0x3ffc0008,len:0
load:0x3ffc0008,len:1964
load:0x40078000,len:3668
load:0x40080000,len:260
entry 0x40080034
I (354) heap_alloc_caps: Initializing heap allocator:
I (355) heap_alloc_caps: Region 19: 3FFB4790 len 0002B870 tag 0
I (356) heap_alloc_caps: Region 25: 3FFE8000 len 00018000 tag 1
I (366) cpu_start: Pro cpu up.
I (372) cpu_start: Single core mode
I (378) cpu_start: Pro cpu start user code
I (402) rtc: rtc v160 Nov 22 2016 19:00:05
I (413) rtc: XTAL 40M
I (579) phy: phy_version: 258, Nov 29 2016, 15:51:07, 0, 0
I (971) cpu_start: Starting scheduler on PRO CPU.
I (973) SoftAP_Server: Setting UART configuration number 2...
I (973) UART: queue free spaces: 10
ESP32 uart Send

[ESP_igrr]

You need to specify some real pin number instead of UART_PIN_NO_CHANGE at least for the TXD pin. It will help if the pin you set is the same pin which you are probing with the scope.

[WiFive]

You need to specify some real pin number instead of UART_PIN_NO_CHANGE at least for the TXD pin. It will help if the pin you set is the same pin which you are probing with the scope.

Maybe worth documenting with uart_set_pin function which UART have default pins and what they are?

[vinimac]

Hello,

I have same issue, but I am not using default pins. In scope, there is no TX signal.

Code: Select all

#define RS485_TX            34
#define RS485_RX            22
#define RS485_DE            19

#define RS485UART           UART_NUM_2

uart_config_t uart_config = {
        .baud_rate = 9600,
        .data_bits = UART_DATA_8_BITS,
        .parity = UART_PARITY_DISABLE,
        .stop_bits = UART_STOP_BITS_1,
        .flow_ctrl = UART_HW_FLOWCTRL_DISABLE
    };
     // RS485 configuration
    uart_param_config(RS485UART, &uart_config);
    // RS485 pins
    uart_set_pin(RS485UART, RS485_TX, RS485_RX, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);
    ESP_ERROR_CHECK(uart_driver_install(RS485UART, 128 * 2, 128 * 2, 0,
                                        NULL, 0));

[WiFive]

34 is input only, you can use for rx but not tx

[vinimac]

OMG, I cannot believe I missed this!

Thanks very much for the reply.