ESP32 Forum

Posted: **Fri Mar 13, 2026 7:07 am**

Hello,

Using a variant "waveshare_esp32_s3_touch_amoled_241" I'm not have any success trying to read characters from stdin.

Starting with the "hello_world_main" example from ESP IDF, the following has been added as a task during the countdown:

Code: Select all

void reader( void *pvParameters ) {
    printf("Reader . . \n");
    while ( 1 ) {
        char ch = getchar();
        if ( ch < 255 ) {
            printf("Read %c %d\n", ch, ch );
        }
        vTaskDelay(5);
    }
}

The line "Reader . ." is displayed, but then 255 is only ever returned by "getchar()", even with copious ponding on the serial console keyboard.

--

Posted: **Fri Mar 13, 2026 8:19 am**

Code: Select all

#include <stdio.h>
#include <inttypes.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_log.h"

static const char *TAG = "MAIN";

void app_main()
{
    printf("Reader . . \n");
    while ( 1 ) {
        char ch = getchar();
        if ( ch < 255 ) {
            printf("Read %c %d\n", ch, ch );
        }
        vTaskDelay(5);
    }
}

This code works correctly.

Reader . .
Read 1 49
Read 2 50
Read 3 51
Read 4 52
Read 5 53
Read 6 54

Posted: **Fri Mar 13, 2026 8:51 am**

I tried your code complete, and again for me it's not indicating any data being received (I tried with both "screen" and "idf.py montitor"). The output of the ESP32 is displayed, but data sent to the ESP32 is not received.

That is puzzling.

What ESP32 are you using?

The Waveshare board being used as GPIO 19 and 20 connected directly to a USB-C port.

"idf.py flash" works, so it must be a configuration issue?

Posted: **Sat Mar 14, 2026 10:43 am**

The Waveshare board being used as GPIO 19 and 20 connected directly to a USB-C port.

This setting is required for USB Serial/JTAG Controller Console.

Posted: **Sat Mar 14, 2026 11:49 am**

Thank you! I must have missed than nuance in the documentation.

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