Things I learned last week (7)

Nexus 10, OTG and Pogo charger

My Mac mini was used for a long time as a MIDI controller but I needed it for something else, so I decided to use my Nexus 10 tablet instead as, with the help of an OTG cable, the tablet can power the MIDI adapter (a M-Audio Midisport 2×2). Because the MIDI adapter is drawing power from the tablet battery, I planned to use a Pogo cable to charge it at the same time. Seems easy enough, right?

Unfortunately the Nexus 10 stops charging from the Pogo cable as soon an OTG cable is connected to the USB port, but strangely the Nexus 10 still displays a charging state (I checked with an ammeter), which looks like a bug in the code. I would also classify the fact that it stops charging as a bug.

So now I’ll have to remember to unplug the OTG cable (not just the MIDI adapter) after each session so the tablet can charge, but unfortunately that’s not all. As I was doing those tests, I discover that when the OTG cable is disconnected, the Pogo charger does not go back to full charge (~1.6A) but to the nominal USB charge (i.e. 0.5A). That make a big difference in the time needed to charge the tablet. So not only I need to remember to unplug the OTG cable, but I also have to unplug and plug again the Pogo cable so the full charge mode is used. Looks like another bug in the charging logic.

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