Quote:
Originally Posted by s1900ahon
Virtually no current passes through the brake/coast jumper.
On the Jaguar (I cann't speak for the design of others, but I can for Jag) the current involved is that in charging the MCU's GPIO input. The GPIO input uses an internal (to the MCU) pull up which is on the order of 50 kohms. The isolator would only have to pull the input below VIL.
Note that this opto isolator, like the one on Jaguar's PWM input, is inverting.
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If there is virtually no current, couldn't you just move the resistor and output tap to the ground (emitter) side and re-invert passively?
In any case, I was thinking of using the phototransistor side directly as a switch between the center pin and the brake/coast pins. To do this, you would only need to know whether the jumper pulled the B/C pins up or down.