Badges sometimes won't turn on?

[OrenLederman]

Remember the problem with the badges sometimes not turning on (until you discharge the large capacitor)? It's something that we mostly saw after programming the badges.

I did a small test - turned off the badge, connected the battery's VCC to the GND side of the capacitor and then turned on the badge - it won't start. conncet the VCC and GND of the 100uF and then it works. Do the same for the 4.7nF capacitor on the SWD pin and then it work. Short circuiting VCC and GND in the programming pads also works. But shortcircuiting the pads next to the battery does..

I tested it on two 3v4 badges, with the same results. Sometimes you need to keep the connection between Battery's VCC and the GND of the 100uF capacitor connected for a couple of seconds.

This problem doesn't seem to happen in the 3v3 badges, by the way, but may require more testing. Some badges seem more sensitive to this than others. Might be a difference between different batteries too.

Also, it doesn't seem to happen on the 3v4 badges if there is no RTC module installed. Hummm.

Maybe worth checking whether we can recreate the problem if we keep the RTC and remove the large capacitor.

I'm adding this to the spreadsheet and I'll open a bug in the github project (so we have a documentation).

We should revisit this after we are done with the scans.

possible causes:

• capacitor is too big
• something withe RTC or it's resistors cause the same affect that
• maybe it's just the RTC alone.. worth looking at teh signals it's sending when this problem appears (maybe it's doing soething that keeps the nRF51 module "awake"
• should try a badge with RTC and smaller capacitor

Oren

[OrenLederman]

It appears that C1 is too big. Better to replace with a smaller one.

[OrenLederman]

Seems to be solved in version 03v6 (#100 ). However, it might just be that taking the battery out with a metal object (screwdriver or sim card tray opener) discharges the capacitor.