The PCIe card shown here allows remote control of two buttons on a desktop computer – power and reset. It is available in two versions, Wi-Fi and Zigbee; here we will be looking at the former. The original buttons are completely bypassed, and the module offers two inputs and outputs isolated by optocouplers. This means it can provide a child lock function – preventing the computer from being switched on from the case. All of this is also available in the RF version, but we’ve opted for the Wi-Fi-only version – for just over $10:
The seller warns that the device does not work on branded computers and requires appropriate BIOS settings.
The whole thing is also available in a PRO version with an additional radio remote control:
Here’s a close-up of the board – there are four pairs of wires, two pairs are inputs and two are outputs. The device, with its factory settings, automatically pairs them; short-circuiting one input (where the button will be) causes a short-circuit in the output (where we’ll connect the motherboard):
The whole thing used to be on a CBU module (BK7231N), but it’s now on the BK7238:
A few words about the app are also in order. Tuya comes pre-installed, allowing you to control it for free from anywhere in the world. It also features a timer and integration with Google, Alexa and similar voice assistants.
Firmware update
However, we wanted to experiment a bit more and flash our own firmware onto it. This is where you need to think carefully, because if you don’t have a server on the internet, there may be a problem with controlling it from behind your router, but this is normal for solutions such as Tasmota or ESPHome. Here, we’ll upload our multi-platform IoT firmware supporting as many as 32 platforms to the module.
We’ve already shown the T1-U-HL pinouts on the forum: Data sheet for the T1, T1-M and T1-3S Tuya BK7238 modules, pinouts and flashing, Home Assistant
You can change its firmware – all you need is a USB-to-UART converter:
First, we burn the firmware using our Flasher, then we upload the OBK:
https://github.com/openshwprojects/BK7231GUIFlashTool
Copy of the firmware:
https://github.com/openshwprojects/FlashDumps/commit/f731ea9b6c9477ab72163f2231dbda793ee3239b
However, the Flasher did not detect the GPIO this time:
We determined the GPIO roles by tracing the paths:
Code: JSON
Log in, to see the code
There are two ways to script the device.
1. in Home Assistant using their automations
2. on the Beken board itself, via autoexec.bat
Autoexec.bat allows the OBK to handle device events and add buttons to the main panel:
alias force_power_off backlog setChannel 1 1; addRepeatingEvent 5 1 setChannel 1 0
alias short_click backlog setChannel 1 1; addRepeatingEvent 1 1 setChannel 1 0
startDriver httpButtons
setButtonEnabled 0 1
setButtonLabel 0 "Toggle Power"
setButtonCommand 0 short_click
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setButtonEnabled 1 1
setButtonLabel 1 "Force POWER off"
setButtonCommand 1 force_power_off
SetChannelLabel 1 PWR
SetChannelLabel 2 RESET
SetChannelLabel 3 PWR_ON
addEventHandler OnHold 21 force_power_off
addEventHandler OnClick 21 short_click
The script above:
- sets the channel names
- adds events that manually map a button click and a long press to a short and long relay closure respectively
- adds buttons to the UI that trigger these events – these will then also be visible in Home Assistant
Screenshot of a panel with a single scripted button:
Similarly, you can add a RESET button (a second button and relay):
This way, you can bring this module to life without the cloud. There is still the matter of the child lock – the remote lock. This can be added by including an additional condition check in the button and event handling via if :
SetChannelLabel 10 "Child Lock"
addEventHandler OnHold 21 if $CH10==1 then force_power_off
Then, click events will only be triggered when we allow them to.
Of course, this is not the only way to configure it. One could, for example, try to hard-code the connection between the buttons and the relays by assigning the inputs the dInput role (digital input) and the same channels as the relays, but then we would lose remote control. The digital value from the inputs would be copied to the outputs. For this reason, scripting seems to be the sensible solution here.
For more information, please visit the project repository , the page with documentation and the examples of OBK scripts .
To sum up , the module seems quite useful. It works well both in its factory-set state, where you immediately gain remote access via the Tuya app, and after a firmware update, when using Home Assistant or a similar system connected to the internet.
The usefulness of this solution is somewhat diminished by the fact that many computers can be booted remotely via Wake-on-LAN. However, this is not always convenient to set up from outside the local network, and some hardware configurations do not support it at all. For this reason, such a module can still prove very practical as a simple way to boot a computer remotely, particularly when combined with a remote desktop configured to be accessible immediately after the system starts up.
In addition, there is the option to remotely reset the computer and use the ‘child lock’ function, which locks the physical buttons on the case.
Can you think of any interesting uses for such a remote PC switch?
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If anyone connects this device, they should check the manufacturer carefully. Mine is very strange: _TZ32981000000_rghq9fag. If it’s different, but the layout looks similar, you can change it to your own.
