Error in UART examples (IDFGH-3839)

[phildimond]

The UART example code for ESP32 has an error. The driver install must come after the configuration.

For example in the esp-idf/examples/peripherals/uart/uart_echo/ example, the code below in uart_echo_example_main.c will not work if the UART is changed to UART_NUM_2 unless the uart_driver_install is moved after the uart_set_pin.

/* Configure parameters of an UART driver,
 * communication pins and install the driver */
uart_config_t uart_config = {
    .baud_rate = 115200,
    .data_bits = UART_DATA_8_BITS,
    .parity    = UART_PARITY_DISABLE,
    .stop_bits = UART_STOP_BITS_1,
    .flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
    .source_clk = UART_SCLK_APB,
};
uart_driver_install(UART_NUM_1, BUF_SIZE * 2, 0, 0, NULL, 0);
uart_param_config(UART_NUM_1, &uart_config);
uart_set_pin(UART_NUM_1, ECHO_TEST_TXD, ECHO_TEST_RXD, ECHO_TEST_RTS, ECHO_TEST_CTS);

[alisitsyn]

Hello @phildimond,

Thank you for the issue.

Could you please provide more information:

1. Which ESP-IDF version you are using?
2. Could you send me the complete code of your example?
3. What kind of board (ESP chip) is used?

I was trying to reproduce the issue with my ESP-WROOM32 board and the echo example from latest master and with release/v4.1. It works correctly with the UART_NUM_2 as well with UART_NUM_1 on my side and is able to return echo. I used the code you provided for initialization of UART as well as original code.

[phildimond]

ESP 4.1

Code was the example as quoted. I was having trouble with my code so I went back to the example and had the same issue with it, until I swapped the order of the calls.

Devkit-C (new with V3 ESP-WROOM-32D)

Phillip Dimond Consulting Engineer, Gaming Systems Phone: 0409-748433 Intl: +61-409-748433

From: Alex Lisitsyn notifications@github.com Sent: Saturday, 7 November 2020 2:24 AM To: espressif/esp-idf esp-idf@noreply.github.com Cc: Phillip Dimond phil@adgaming.com.au; Mention mention@noreply.github.com Subject: Re: [espressif/esp-idf] Error in UART examples (IDFGH-3839) (#5746)

Hello @phildimondhttps://github.com/phildimond,

Thank you for the issue.

Could you please provide more information:

1. Which ESP-IDF version you are using?
2. Could you send me the complete code of your example?
3. What kind of board (ESP chip) is used?

I was trying to reproduce the issue with my ESP-WROOM32 board and the echo example from latest master and with release/v4.1. It works correctly with the UART_NUM_2 as well with UART_NUM_1 on my side and is able to return echo. I used the code you provided for initialization of UART as well as original code.

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHubhttps://github.com/espressif/esp-idf/issues/5746#issuecomment-723138564, or unsubscribehttps://github.com/notifications/unsubscribe-auth/AA3SZ3FRUCMJVSDVRWTATF3SOQIJ3ANCNFSM4QCRDY6Q.

[alisitsyn]

@phildimond,

Thank you for the information. Generally, order of the calling uart_param_config and uart_driver_install can be arbitrary. May be I am missing something but can not reproduce it on my Windows and Linux machine with the DevKitC ESP-WROOM-32D_V4 (what I have now) on release/v4.1. In order to fix this I need to confirm the issue and find reason for this. Could you send me your elf and binary file with the sdkconfig.

Thanks.

[fromeijn]

I'm seeing the same issue when using the pppos_client example and using UART_NUM_2 not sure what the deal is there. UART is not behaving and i'm missing data etc. I'm on v4.2. Chip used for testing is ESP-WROOM-32U. Using UART_NUM_1 works fine.

[AxelLin]

@phildimond,

Thank you for the information. Generally, order of the calling uart_param_config and uart_driver_install can be arbitrary.

Are you sure? Q1: What is the expected driver behavior before calling correct uart_param_config? Q2: What is the expected driver behavior before calling uart_set_pin?

IMHO, the init order does matter, e.g. 0784426d6b6a0d1e97a7594493b2c80e82070404

[AxelLin]

@phildimond,

Thank you for the information. Generally, order of the calling uart_param_config and uart_driver_install can be arbitrary.

https://github.com/espressif/esp-idf/issues/6589 show the order does matter.