Itchy: End Stops

An end stop has two states. So, if A is triggered to make Dir explicitly head away from the stop, then /A will also have a change in state, which can be used to feed in info telling the machine there has been a hard stop. This can be used both for zeroing, and for a full ‘WTF all brakes on how did you get out of bounds’ that happens in software – but that is a slave to the directional change we apply directly to the DIR pin. It might be a toggle gate/flip-flop.

The electronics of this may need testing, but it should be possible to hit a high pin to ground and not have the direction go high. That is, to have the grounding effect be bigger than the directional instruction, If not, the software still works. Pull-up/pull-down resistors may be involved at the pin end. Need to dig out whether you can have a resistor as an out pin. Don’t think so. But as an in pin would be fine. Still, it takes an extra pin in.