Sending AT commands over UART - c

Question

My problem is sending AT commands over UART. I am working with STM32 IDE. I have the hardware: STM32L476 with a sensor shield together with the ESP01 Wifi module.
I got the hardware to work and can already send the first AT command over Uart to ESP01. When I try other commands AT+RST or AT+GMR I don't get any response back.
I use this code to send over UART to ESP01.
void ATsend (char out[]){
HAL_UART_Transmit(&huart4, (uint8_t *)out, strlen(out), 1000);
}
The code below works fine
ATsend("AT");
I get the response OK.
When I try this I get no response.
ATsend("AT+RST")
Any tips?

Answer 1

If you are sure that your UART receiver, or your DCE in RS-232 notation, supports the commands you're sending, this guide might be helpful:
https://docs.espressif.com/projects/esp-at/en/latest/esp32/faq.html#when-the-host-mcu-sends-an-at-command-to-the-esp32-device-there-is-no-response-what-is-the-reason.
The guide indicates as a possible solution also for the ESP8266 products the following: <<When the host MCU sends an AT command to the ESP32 device, there is no response. What is the reason?
A terminator (“ATrn”) must be added after an AT command when the host MCU sending AT commands to an ESP32 device. Please see Check Whether AT Works.>>
There's also this link: https://docs.espressif.com/projects/esp-at/en/latest/esp32/Get_Started/Downloading_guide.html#check-whether-at-works.
I hope these suggestions can solve your problem. At least they can indicate to you if the device is working.
There might be other causes of malfunction, but in this case I need more information to help you solve them and I suggest that you write to my company for professional support.
Yours sincerely,
V.D.