ESP32 s3 UART2 loopback response is abnormal

[marco2009]

I found the UART_NUM_2 of ESP32 s3 does not work like the other uart ports in my project, therefore I coded the following loopback test in Arduino IDE, and the result are the same; normally "output" should be equal to "input" and "i", but only UART2's "output" gives the previous number as showing in the figures.

I would like to ask if there is a bug in UART2 of ESP s3 or I made some mistake. Thank you.

Code: [Select all] [Expand/Collapse]

1. //ESP-IDF Components
2. #include "esp_log.h"
3. #include "driver/uart.h"
4. #define uart_num UART_NUM_2 // UART_NUM_1 and UART_NUM_0 work, UART_NUM_2 did not
5. char input[1];
6. char output[1];
7. void setup() {
8.   uart_config_t uart_config = {
9.     .baud_rate = 115200,
10.     .data_bits = UART_DATA_8_BITS,
11.     .parity = UART_PARITY_DISABLE,
12.     .stop_bits = UART_STOP_BITS_1,
13.     .flow_ctrl = UART_HW_FLOWCTRL_CTS_RTS,
14.     .rx_flow_ctrl_thresh = 122,
15.   };
16.   // Configure UART parameters
17.   ESP_ERROR_CHECK(uart_param_config(uart_num, &uart_config));
18.   ESP_ERROR_CHECK(uart_set_pin(uart_num, GPIO_NUM_33, GPIO_NUM_34, GPIO_NUM_NC, GPIO_NUM_NC));
19.   const int uart_buffer_size = (1024 * 2);
20.   QueueHandle_t uart_queue;
21.   // Install UART driver using an event queue here
22.   ESP_ERROR_CHECK(uart_driver_install(uart_num, uart_buffer_size, uart_buffer_size, 10, &uart_queue, 0));
23.   uart_set_loop_back(uart_num, 1);
24. }
25.  
26. void loop() {
27.   input[0] = 0;
28.   for (int i = 0; i < 0x100; i++) {
29.     uart_write_bytes(uart_num, input, 1);
30.     delay(1000);
31.     uart_read_bytes(uart_num, output, 1, 0xffff);
32.     ESP_LOGE("input", "%x, %x", i, *input); //input[0] should be equal to i
33.     ESP_LOGE("output", "%x, %x", i, *output); //output[0] should be equal to i
34.     input[0]++;
35.   }
36. }

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normal.JPG (33.87 KiB) Viewed 745 times

^ Normal output by defining the uart_num as UART_NUM_1 or UART_NUM_0

uart2.JPG (41.61 KiB) Viewed 745 times

^ Abnormal output by defining the uart_num as UART_NUM_2

[josephl]

I am using an ESP32-S3-WROOM-1, also having an issue with UART2. The output of UART2 seems to be delayed, with the data getting "stuck" in the buffer until the next read occurs, causing the output to be offset. This seems to be a bug, which I wouldn't have even considered until I found this post. UART1 works correctly. Not sure how this can get reported and fixed?