int _write(int fd, char *ptr, int len)
{
    HAL_UART_Transmit(&huart2, (uint8_t *)ptr, len, 1000);
    return len
}

int _read(int fd, char *ptr, int len)
{
    char* data;
    int i;
    for (i = 0; i < len && HAL_UART_Receive(&huart2, &ptr[i], 1, 20) == HAL_OK; i++)
        ;
    return i;
}

...

main() {
    char response[256];
    char* result;

    while(1) {
        printf(SYSRESET);
        result = fgets(response, sizeof(response), stdin);
        if (result != NULL) {
            printf(result);
        } else {
            clear(stdin); // clear eof flag, timeout
        }
    }