N900 Software BME

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Unsorted adds:
Unsorted adds:
Then there's also /usr/lib/hal/hald-addon-bme, which seems not to be completely out of order (according to lshal) even when bme_RX-51 is stopped.
Then there's also /usr/lib/hal/hald-addon-bme, which seems not to be completely out of order (according to lshal) even when bme_RX-51 is stopped.
 +
Mer 'replacement hald-addon-bme': http://gitorious.org/mer-toggles/hald-addon-bme/blobs/master/hald-addon-bme.c
lsof -p `pidof bme_RX-51` gives an idea about what BME is actually interfering/interfacing with, and a strace will show it talks to dsme_lib probably to implement the watchdog timers.
lsof -p `pidof bme_RX-51` gives an idea about what BME is actually interfering/interfacing with, and a strace will show it talks to dsme_lib probably to implement the watchdog timers.

Revision as of 16:36, 9 May 2010

This page is to bring together efforts and links for those working on understanding BME - the battery managment entity.

This is required to implement user friendly Host Mode

BME is divided into three parts.

  • Kernel driver that handles all of the low-level interaction with the hardware.
  • hald-addon-bme - an add-on process for HAL that reports status.
  • bme_RX-51 - Process started early in boot, with watchdogs to reboot the device if it malfunctions.


The kernel driver is split over several files.

http://mxr.maemo.org/fremantle/source/kernel/include/linux/i2c/twl4030-madc.h This handles reading various ADCs to readout voltages and currents.


Unsorted adds: Then there's also /usr/lib/hal/hald-addon-bme, which seems not to be completely out of order (according to lshal) even when bme_RX-51 is stopped. Mer 'replacement hald-addon-bme': http://gitorious.org/mer-toggles/hald-addon-bme/blobs/master/hald-addon-bme.c

lsof -p `pidof bme_RX-51` gives an idea about what BME is actually interfering/interfacing with, and a strace will show it talks to dsme_lib probably to implement the watchdog timers.

BME process/file is called /usr/sbin/bme_RX-51 killing or sigstop'ing it will cause immediate or delayed reboot it's easily suspended though thru upstart process management by

  • ~>stop bme

and resumed any time by

  • ~>start bme

A nice little experiment to investigate the bq24150 USB Battery Charger chip's abilities is to

  • plug in Nokia wallwart charger
  • ->stop bme
  • wait max 32s until bq24150 internal watchdog timer expires (due to bme not resetting it), which will cause bq24150 to reset to defaults, which are a mostly sane, safe charging without any software support. You can tell this by bq24150 firing up the hardwired steady yellow indicator LED

I'm about to write a first draft little script to somewhat replace bme's basic functions, eventually turning this into a real project Just-Replaces-BME aka jrbme (some say it's "JRBME replaces BME", according to an age old tradition of linux self referencing ETLA [like GNU=="GNU Not Unix", KDE=="KDE Desktop Environment"])