HLK RM04

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at-commands

Hi everyone,

I am facing an issue with my HLK-RM04 Wi-Fi module and would appreciate any help.

Hardware connections:

  • Pin 1 (VCC): +5V
  • Pin 28 (VCC): +5V
  • GND: Connected properly
  • ES/RST pin: 3.3V
  • Pin 20 (RXD): Connected to MCU TX
  • Pin 21 (TXD): Connected to MCU RX

Problem:
The module powers up, but it does not respond to any AT commands sent through UART.

Questions:

  1. What is the correct procedure to enter AT Command Mode on the HLK-RM04?
  2. Does the ES/RST pin need to be pulsed LOW to enter AT mode?
  3. What UART settings should be used (baud rate, data bits, parity, stop bits)?
  4. Is there any LED indication that confirms the module has entered AT mode?
  5. Has anyone experienced a similar issue where the module powers up but gives no AT command response?

Any suggestions for troubleshooting would be greatly appreciated.

Thank you.

1 Answers

Hello, pls check the following answers for your question:

  1. Lower ES/RST by 100ms6s before entering AT
    2.100ms    6s enter AT,>6s restore factory
  2. Baud rate 115200
    Data bit 8
    No checksum (n)
    Stop position 1
  3. There is no light to confirm, the light is WiFi
  4. No, just confirm the power supply and operation mode to enter. If the operation mode is correct, you need to confirm whether the power supply is abnormal, 5V+800mA

Additionally, production of the HLK-RM04 has been discontinued for a long time. Please note that for your new projects, kindly select our alternative Wi-Fi module: HLK-7628N.
Following is the manual link: https://drive.google.com/drive/folders/1Z8-RLZVs9jjOHwORsGWpotGak7IFOwQo

HLK-Ellen266
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