Rather than using a reed relay, you could use a small solid state relay. You drive them like an optocoupler. Then the output can usually be be polarity insensitive (either due to internal wiring, or appropriate external wiring).For your diagram, add series resistor 330 Ohm between pico GPIO and optocoupler sender(led).
When connecting the buttons, the optocoupler transistor needs to be connected in the correct polarity. Measure across each button where '+', '-' is. Instead of using optocoupler there could be reed relay used. But this gives some more complexity as a transistor is needed to drive the coil.
For example, search for ASSR-1410, ASSR-1411 and ASSR-1420 (Broadcom, formerly Avago).
This way you can just connect the SSRs across the pushbuttons, without having to worry how they are wired.
Statistics: Posted by stevend — Tue Mar 18, 2025 10:32 pm