Brick Buddy 3 Issue

 

Ran into an interesting problem.  I have 5 of the new controllers completely built with BT.  Two of them will reset when running a motor.  But only when using the AUX power port.  The board is powered through the USB port when developing and programming.  Only when it is installed, had I intended to use the AUX power port.  The AUX port connector is the same type as the other connectors I have used though out the Space Base.

This is the AUX input.  Diode or'ed with VUSB

This is the USB input

This is the motor controller I have used for years.

VPWR feeds two DC-DC converters that make 5VDC and 9VDC(Buck-Boost so it will run from an input of 3.3VDC to 20VDC).  The 5VDC has a 3.3VDC LDO on it for the PIC, BT, Memory, etc and that LDO has a 1.8VDC LDO for LED Controller core.

Working Observations

• Works on USB port powered by USB HUB, Phone Charger and all battery Packs
• Works on AUX port powered by USB HUB, phone charger and some battery packs

Non Working Observations or tried this, did not change behavior

• Added 220uF cap at VPWR
• Added 22uF caps on motor controller (C40,C41)
• Tried different cables
• Sometimes will cause the battery to shutdown, other times just causes a reset

Obviously there is something about some of the batteries and the aux port. 

• Does the PI filter network on VUSB make that much difference.
• Did my Chinese builders use crappy caps for the build.  I specified X5R and they said that is what they used.
• How is the 9V bus radiating back through the DC-DC and effecting the 5VDC.
• Are these battery power backs at the end of their life ( ordered a new one from Amazon, we shall see)

Anyway I am moving on, just have to remember which battery pack goes to which model for now or bring out the USB connection.