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By marquedl
#86194 Hello pilol34,
I liked the answer to the HW-655, it looks very clean and alleluia! But when I tried it with three relay modules it does not work. The STC-ISP gets stack on "Checking target MCU ... ". I tried different settings to no avail.
After probably 16 hours I am ready to throw the towel but I refuse to give up.

Is there anything that you are omitting like the STC-ISP settings, resetting the MCU, ...?
I have the same results as Bizebua.

In very, very few occasions I ask a question but this time around I have run out possible leads.

Thanks, DMq
User avatar
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