Re: Sierra C885 nightmares

[Marius Kotsbak <marius kotsbak com>]

2012/12/28 Aleksander Morgado <aleksander lanedo com>

Hey Dan, Marius & everybody,

I recently got a <irony>wonderful</irony> Sierra Wireless C885 modem
from eBay...

I fixed several obvious issues in MM git master to have it connected,
but I'm stuck with several things that I don't really know how to
properly handle.

1) SIM lock after power up
So, we power-down the modem with CFUN=4 and we recover full
functionality mode with CFUN=1,0 (0 to avoid the reset). But, if the SIM
has PIN enabled, the modem will require SIM unlock before going on. If
you don't provide the SIM, it will end up replying ERROR to every next
command sent.

I don't understand the problem. Why not just run +cfun? and check if an unlock is required (instead of waiting for errors), and if so, unlock it. Is the problem that modemmanager does not have the PIN at that time?

 

I tried to handle this by catching the SIM PIN and automatically
re-sending it after the power up when needed. See
'sierra-pin-after-power-up' branch in git. But, then I got to the next
problem:

2) The modem is not reliable at all. Lots of times, CFUN=1,0 really ends
up resetting the modem while we're waiting for the OK reply. Fixing the
lock after power-up is only meaningful if the modem really always
powers-up without reset in CFUN=1,0.

Hmm, do we power down for saving power, or also save init time? Why not just assume that the modem is reset after running cfun=1,0, unlock and init it if required?

--

Marius