hardware

Stuff has bugs, both hardware and software. One of the hardware bugs in Openmoko phones has been bug number #1024 causing things to happen that prevent the GSM chip to go to ‘deep sleep’ mode to save power.

Someone came up with a fix: add a capacitor.

So we did.

Wiki page with instructions to detect if you’re hit by the bug: http://wiki.openmoko.org/wiki/1024
Bug report: http://docs.openmoko.org/trac/ticket/1024
Instructions to fix the bug: http://www.neofundas.blogspot.com/

After opening the case

Small, isn't it?

One end soldered to the ground

Other end soldered to the old capacitor

Thanks Antti & open hardware!

Results

The suspend power consumption dropped to around 6000 µA from around 15-20000µA when I now allow the GSM modem (Calypso) to go to deep_sleep mode. The 1200mAh battery should now give up to 200 hours = 8 days of power. Of course this is theoretical – I also need to use the phone to make calls, let GPS show me my location etc etc – and as I move, the GSM needs to wake up ever now and then because of the changing base stations. So nowadays I recharge it every other night still being able to make calls and do other stuff with it. Nice improvement!