Pocket Reform charging question

MNT Pocket Reform
21

With one problematic charger here I found reversing the usb-c plug helps. Could try that.

22

I have a rudimentary usb-pd debugger - it doesn’t show all traffic or requests, but it does show some unusual behavior from the pocket.

Header Message Type Message Body Source Decoded
0x4161 Source_Cap 0801912C
0002D12C
0004B0C8
00064096		 charger 0801912C - Unconstrained, 3 amps, 5 volts
0002D12C - 3 amps, 9 volts
0004B0C8 - 2.2 amps, 15 volts
00064096 - 1.5 amps, 20 volts
0x4161 Source_Cap charger
0x4161 Source_Cap charger
0x4161 Source_Cap charger
0x4161 Source_Cap charger
0x4161 Source_Cap charger
0x4161 Source_Cap charger
0x1242 Request 41000401 pocket 4th object, no usb suspend, 10 ma, max 10 ma
0x0363 Accept charger
0x0566 Ready charger

This test was with the pocket som (rcm4-a311d) powered off - when the pocket som is powered on, I get no data on my debugger (more likely a limitation of my debugger). Charger is a “anker powerport speed 30”

  • The number of source capabilities messages is odd - sometimes i’d see 20+ messages from the charger before the pocket would respond with a request. (I have a capture from an ipad, and it only needed one source capability message from the same charger before requesting)
  • The pocket is setting the max amperage and requested amperage to only 10 ma - I don’t know how chargers are expected to respond to this behavior - but this is out of spec (the pocket then goes on to draw more than 10 ma)
4 Likes
23

I would occasionally get into the loop of charge/not charge with an OEM 200W charger Random shutdown and the development version of sysctl firmware that has PD improvements resolves the problem with this charger. Note that while the charger has technically a number of ports and high output power only two of the USB C ports can be used reliably. When 3 ports are used the charger firmware starts to struggle with allocating power between the ports, and a reconfiguration loop can happen on the charger side.