FW 00.04+ = rare bug - power node doesn't respond and what to do
Bruce Boyes
We have seen a rare case, in FW 00.07 (not released yet), and may
exist back to FW 00.04, where the power node starts up with the high
nibble set (indicating fore and aft sensors are detecting objects),
even though the sensors aren't enabled. They are stuck in this mode
and won't respond to any !PPE commands either. This is very hard to
reproduced and doesn't occur most (99% or more) of the time. So
chances are you won't see this. But if you do:
It's important to keep in mind that the power controller is actually
powered any time the jumper JP6 "Battery Power ON" is closed, even
iff the robot is "off". So using the power button to turn the robot
off doesn't actually reset the power node and fix this problem.
What does reset the power node is removing the P6 jumper while
TrackBot is running and corner LEDs are blinking. Leave the jumper
off for a minute or so to be sure the on board capacitors are really
discharged and the power node is not still running (it can run on
less than 2 volts, very low current draw). Press the power button to
help discharge the power supply caps.
Then reinstall the P6 jumper and start TrackBot via the power button.
Check response to a ?P command. After powerup, sensors are not
enabled, so the high nibble must be zero. If it is "F" then the power
node is still stuck.
In your application code you should do a ?P before a !PPE, and check
to see if the high nibble is set. If it is, that's a serious error
since you will likely not be able to use the fore and aft sensors
without a P6-removed power cycle.
A reset in this manner has always worked for me, and it's almost
impossible to reproduce if you want to see the problem.
We are addressing this issue in the next firmware release.
best regards
Bruce Boyes
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