That board looks like it is designed to handle inputs to something like the Pi, rather than drive outputs. The resistors on the input side seem to be aimed at receiving a higher voltage input than the Pi would be giving them (5v, 12v etc) and the outputs look suitable for driving GPIO pins. It could work, but you'd need to fit the "user option" resistors with values suitable for 3.3v.simple972 wrote:what do you think about this?rpdom wrote:It depends on how much current the connections take. I'd assume not a lot as they are just push buttons. In that case I'd go for simple opto-isolators to keep the Pi electronics separate from the bed electronics.
You say that connecting the other pins to pin 2 makes the bed function. That doesn't mean it is ground (unless you tested with a meter). It could be +5v or +3.3v or any low voltage. You'll need to check the polarity first. But I don't see any real problems with getting it working.
Circuit would be something like this crude ASCII art for each pin.
Code: Select all
------ GPIOx----[Resistor]---|OPTO|----Bedx |ISOL| GND-------------------|ATOR|----BedCommon ------
We still need to find out how much current is required to trigger the bed, even though I strongly suspect it is just a few tens of milliamps at most. Perhaps one of the other people who are looking at similar units can make a measurement with an ammeter across one of the buttons. The voltage would be good to know too, but that is also going to be low for safety reasons.