Sanguinololu & opto endstops :S (3 replies)

Hi there,

I am modernising my old Prusa, which involves a newly-soldered sanguinololu board. I used to have Gen 3 electronics and I want to re-use the old opto endstops (v2.1).

When no endstops are attached to the electronics board, I read 5V between GND and V+ (or SIG if I switch it in the firmware). But when I plug in the endstop, I read ~1.8V at SIG and ~0.9V at V+. The LED does not light up on the endstop board and nothing happens when I trigger the opto switch. These endstops worked just fine with the old electronics, so why not with the Sanguinololu?

Thanks.