GSM modem power on/off issues at gta01
Sean Chiang
sean_chiang at openmoko.com
Fri Feb 29 05:24:04 CET 2008
HI! list,
Here's my recent observation about the power management of GSM modem
within gta01,
just a note. If we want to power off GSM modem _completely_ we need to
issue AT at POFF
to modem and subsequently echo "0" > power_on.
Without AT at POFF, even shutdown the gta01 the battery life still be
consumed by GSM modem.
My misunderstanding is the GSM modem could be power on/down only one
time, after you power
off GSM modem, you couldn't power on modem anymore. And I'm wrong, the
modem could be
powered on|off by echo "1"|"0" > power_on repeatedly.
A wrapper called gsm-pm which is called by init when device on, is used
to control the on/off GSM modem. gsm-pm will
power on modem then run gsmd. After that, gsm-pm will wait until gsmd is
killed. When gsm-pm detect the gsmd
was killed it will send "AT at POFF" to modem then echo "0" to power_on.
With this we doesn't need to worry the gsmd is dead or not. I tried to
write the gsm-pm, could be download from
http://svn.openmoko.org/developers/sean_chiang/gsm-pm/ I still have
problem when write AT at POFF to modem.
Is this idea ok?
-Sean Chiang
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