Cycle Analyst v3 - Speedo Pulse Resets MCU

[randysway]

Mornin folks. I'm having a bizzare issue with my Cycle Analyst, involving the speedometer.

Every time a pulse happens (Sp pulled to ground) the MCU resets (rebooting the device). This happens regardless of whether I use a reed sensor and single magnet or splice in the signal from a motor hall sensor. The diode placed in series with the speedo pad on the CA's PCB is functioning correctly, and I haven't a clue where to go from here.

Has anyone encountered this issue before?

 

[amberwolf]

If the same thing happens even if just manually grounding the Sp pad on the PCB, then that eliminates wiring itself (like induced noise, etc).

I guess if the 5v from the CA was loaded down enough for the small extra load thru the pullup resistor on that pad while grounded to drop it enough to cause the MCU to lose power, it might do this.

Just for kicks, you could unplug everything else from the CA (throttles, ebrakes, PAS, torque sensor) that is potentially powered by the 5v or other non-battery-voltage lines. Retest, and if the problem stops, then one of those is possibly loading the power down. Start plugging them back in and retest, and when it comes back, unplug the *other* device(s) and see if it goes away again. If not, then that specific device is causing it, directly or indirectly. If it does, then it's a cumulative load problem, and you can then measure the actual 5v line with and without each device plugged in to see how far it drops with each one. If it drops much with any one device vs the others, it's the likely culprit, if it drops much with all of them (one at a time or together) but no specific one more than others, then there might just be a general problem with the CA's 5v source.

IIRC there is an issue with packs above a certain voltage lowering the load limit on the *10v* line (torque sensor), but I don't recall that with the 5v line, and don't know if it would affect the 5v.