Control standing desk with a Raspberry Pico

Forums › Home Workshop DIY › Control standing desk with a Raspberry Pico

boland

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#299480 11-Sep-2022 15:50

I've got this electrical standing desk with a simple up/down controller. I'm missing memory settings, so I'm thinking to buy a Raspberry Pico with a couple of buttons, and a distance meter. When one of the new buttons is pressed, it will send a signal to to either up/down on the existing controller, to a certain height.

The one thing I'm not sure about is how to trigger up/down on the existing controller. It will involve some soldering. See a photo of the up/down controller here. Switches are next to "SW1" and "SW2". SW1 is up, SW2 is down.

How do I control these switches from my Pico? My understanding of a switch is that when pressed, it will short circuit between the two pins. Sut short circuiting two GPIO's is generally not advised though.
Would it be sufficient to connect one of the pins to one GPIO and set it to 0 (GND) or 1 (high)? If high, what voltage should I use?

Just on a side note, I'm very new to all of this, this will be my first Pico project. Before I do anything stupid I'll play around with a basic starter kit with leds etc :)

timmmay

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#2965929 11-Sep-2022 20:16

Wouldn't it be easier to just push the buttons?

If you're going to do it though, go the whole hog. Have it hooked up to Alexa or something and have it work with voice commands :)

davidcole

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#2965932 11-Sep-2022 20:46

I came to similar conclusion. Rather than work out all the controller sods, I’m just implementing a motor and a 3 way switch.

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boland

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#2965933 11-Sep-2022 20:48

timmmay:
Wouldn't it be easier to just push the buttons?

If you're going to do it though, go the whole hog. Have it hooked up to Alexa or something and have it work with voice commands :)

It's a hobby project, yeah, pressing the buttons is easier.
Hooking up to eg Alexa will then be possible too.

boland

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#2965934 11-Sep-2022 20:50

davidcole: I came to similar conclusion. Rather than work out all the controller sods, I’m just implementing a motor and a 3 way switch.

Yeah, controlling the motor directly is an option but then it bypasses the overload protection that's built into the controller.

I think a relay or transistor should be able to control the button on the controller.

dasimpsonsrule

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#2965942 11-Sep-2022 22:43

Looking at those pictures the micro in the up/down controller runs from 3.3V and those buttons look like they pull down to ground. If you setup 2 GPIO of the RP2040 as open drain you should be able to connect it directly to the buttons and trigger them. The port on the edge is for programming the MCU that is on board

hairy1

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#2965947 12-Sep-2022 02:50

Check out this esphome project this guy did.

https://github.com/tjhorner/wifi-desk-controller

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boland

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#2965953 12-Sep-2022 07:47

dasimpsonsrule:

Looking at those pictures the micro in the up/down controller runs from 3.3V and those buttons look like they pull down to ground. If you setup 2 GPIO of the RP2040 as open drain you should be able to connect it directly to the buttons and trigger them. The port on the edge is for programming the MCU that is on board

Thanks. That was what I was thinking too. I'll double check what it's running on before I connect any live current :)

boland

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#2965954 12-Sep-2022 07:48

hairy1: Check out this esphome project this guy did.

https://github.com/tjhorner/wifi-desk-controller

Interesting one, but that one requires the buttons to be connected via RJ45. Won't work in my case.