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By pilol34
#86217 Hi Bizebua

The module must be turned off before you start programming it and after starting the burn operation you re-power the module.


Bizebua wrote:Hi there!

I tried to do the flashing of the STC 15F104W on my ESP-01 board, as explained below by pilol34.
- I use an FTDI232 interface, jumper setting: 5V
- Download the software - ok (I use Win 10)
- Connection between the FTDI232 and the relay board:
5V - 5V
- I removed the ESP8266 module from the relay board

When I start the STC-ISP (V6.87B) tool, I set the COM port (=#4 in my case), the MCU type (STC15F104W) and press "Check MCU". From here, nothing happens.
Even when changing TX-RX and RX-TX connection, no result.

What am I doing wrong?
Any advices for me?

Thanks a lot!
Best regards!

User avatar
By pilol34
#86236 Good morning all;

It is not easy to debug a module because several possibilities could be the cause of the problem.

  1. To begin with, I offer you a first simple program that will allow us to validate the proper functioning of the equipment and the smooth running of its programming. This program causes the module LED to flash every 2 seconds and you can hear the relay click every second.

    File: LcWifiRelayBlinkV1_0_11mhz.hex
    Code: Select all:0300000002011EDC

    If the relay does not work normally, check resistors R3 and R4.
    R3 = 4.7K (472)
    R4 = 10K (103)

    If LED flashes too slow or too fast, check clock speed setup in the burn program STC-ISP because the clock speed is very important for the proper functioning of the program.
    H/W Option -> Input IRC frequency -> 11.0592 MHz

  2. If all went well you can try my new firmware version which I have added some additional internal configurations such as the Watchdog management.

    File: LcWifiRelayUartV1_1_9600_11mhz.hex
    Code: Select all:0300000002017387

  3. To finish, I really appreciated the idea suggested by some to use the code of the SONOFF generic to control the module so I offer you this new code which allows to pass the state of the pin GPIO1 directly to the relay, then you will not need your soldering iron.

    File: LcWifiRelayByPassP30V1_0.hex
    Code: Select all:03000000020100FA

    You can get the SONOFF code for the ESP-01 module on

    Configuration -> Configure module -> TX GPIO1 Serial Out -> Relay1i(29)


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User avatar
By Liam Aps
#86724 Not sure if this has been posted before... Soldering required for this fix.
I found this to be the simplest fix for me.

1) Remove STC15F104W chip
2) Short pins 6 and 7 on pad where STC15F104W was removed
3) In Tasmota firmware, configure ESP-01 (ESP8266) RX=Relay1

April 9-2019
User avatar
By cgmckeever
#87769 Appears many have found this thread.

Some observations:

- There appear to be at least 3 different versions of this board.
--- I can confirm the one labeled v3 works out of the box sending the serial commands referenced in this thread
--- There is one labeled HW-655 that seems to work out of the box (unconfirmed)

As others have stated, with some modification, these will work. There are at least 3 different modifications listed in this thread that are close. All revolve around removing the microcontroller (

I have success:
- removing the 15F104 MicroController
- Connect v3.3 to GPIO0 with a 10kOhm resistor
- Connect pin 7 of the 15F104 to GPIO0
- NOT removing R4 as others have
- [url="
"]Use Pin 0 high/low for relay[/url]
- Disclaimer: I dont know if this thing will blow up or not

Who knows. Sucks that this board is such a pain in the ass. Re-iterate however, the v3 boards works