ESP32 Forum

Posted: **Mon Jan 31, 2022 1:02 pm**

Hi there!

I have just a very little experience with ESP32 and its UART, tried it and ran into a problem. I want to test a KNX with ESP32, so I assembled a simple setup of 3 devices, made 2 NCN5120 devboards and tried to make ESP32 to communicate with KNX. But for some reason ESP reads a garbage. NCN is configured as 19200 8E1 and connected to GPIO 21/22 pins. Here's my MVE:

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{
    ets_printf("\nStarting\nSDK version %s\n", esp_get_idf_version());

    uart_config_t uartConfig = {
        .baud_rate = 19200,
        .data_bits = UART_DATA_8_BITS,
        .parity = UART_PARITY_EVEN,
        .stop_bits = UART_STOP_BITS_1,
        .flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
        .rx_flow_ctrl_thresh = 122,// Tried also 0
        .source_clk = UART_SCLK_APB // Tried also UART_SCLK_REF_TICK
                      };

    int uartPortNumber = 1; // Tried also 2
    int pinTx = 21;
    int pinRx = 22;

    uart_driver_install(uartPortNumber, 1024, 0, 0, NULL, 0);
    uart_param_config(uartPortNumber, &uartConfig);
    uart_set_pin(uartPortNumber, pinTx, pinRx, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);
    uart_set_baudrate(uartPortNumber, KNX_UART_SPEED);
    uart_set_word_length(uartPortNumber, UART_DATA_8_BITS);
    uart_set_parity(uartPortNumber, UART_PARITY_EVEN);
    uart_set_stop_bits(uartPortNumber, UART_STOP_BITS_1);
    uart_set_hw_flow_ctrl(uartPortNumber, UART_HW_FLOWCTRL_DISABLE, 0);
    uart_set_mode(uartPortNumber, UART_MODE_UART);

    uint8_t byte;

    byte = 1;
    if (uart_write_bytes(uartPortNumber, &byte, 1) != 1)
    {
        ets_printf("Init writte error\n");
    }
    else
    {
        ets_printf("init written ok\n");
    }
    if (uart_read_bytes(uartPortNumber, &byte, 1, 10000 / portTICK_RATE_MS) != 1 || byte != 3)
    {
        ets_printf("Init response read error\n");
    }
    else
    {
        ets_printf("init response read ok\n");
    }

    uint8_t address[4] = {0xf1, 0x41, 0x02, 0x00};
    if (uart_write_bytes(uartPortNumber, &address, 4) != 4)
    {
        ets_printf("Assign address writte error\n");
    }
    else
    {
        ets_printf("Assign address written ok\n");
    }
    if (uart_read_bytes(uartPortNumber, &byte, 1, 10000 / portTICK_RATE_MS) != 1 || byte != 0x21)
    {
        ets_printf("Assign address response  read error\n");
    }
    else
    {
        ets_printf("Assign address response read ok\n");
    }

    while (true)
    {

        int res;
        res = uart_read_bytes(uartPortNumber, (void *)&byte, 1, 10000 / portTICK_RATE_MS);

        if (res == 1)
        {
            ets_printf("%2.2X ", byte);
        }
        else
        {
            ets_printf("\n");
        }

        vTaskDelay(1);
    }
}

I did "read value" by ETS from one of the devices connected to the same bus. And here's its output:

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SDK version 4.3.2
init written ok
init response read ok
Assign address written ok
Assign address response read ok


47 BC 11 07 00 46 F5 54 14 B2 57

For testing I also make a simple MVE with Raspberry pi and Java/NRSerial and it works fine. Init:

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int baudRate = 19200;
NRSerialPort serial = new NRSerialPort(portName, baudRate);
serial.setDataBits(8);
serial.setParity(SerialPort.PARITY_EVEN);
serial.setStopBits(SerialPort.STOPBITS_1);
serial.connect();

The same frame readings (correct):

Code: Select all

Using port /dev/ttyAMA0
Sent reset, got response 0x03
Sent address, got response 0x21
BC 11 07 00 06 E1 00 00 B2

Probably I am doing something wrong when using ESP32's UART. Please advise how to do it correctly.
Thank you!

Posted: **Mon Jan 31, 2022 8:50 pm**

Sorry guys, my mistake. I simply forgot to connect common ground wire rofl

sorry, now everything is working fine

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