ModemManager fails to utilize Modem, when it is not ready yet
cschneider at radiodata.biz
Tue Apr 4 15:41:47 UTC 2023
Hi, I have a SIMCOM_SIM7600E-H modem.
When the Modem is freshly "activated" (eg. after powering on the whole
device, toggling the MPCIE reset pin, unplugging/plugging the MPCIE
card), ModemManager is not able to utilize the modem, it ends in state
Status | state: failed
| failed reason: sim-missing
| power state: on
at this point, when I restart ModemManager (I don't do anything with the
modem itself), it works, the modem is usable, calls, sms, internet
I've looked at the debug output of ModemManager and found this: In the
"bad" case, some of the AT commands fail, where the final straw for
ModemManager seems to be "AT+CPIN?" that is answered with "+CME ERROR:
10" which is interpreted as "SIM not inserted" by ModemManager.
In the "good" case the answer to "AT+CPIN?" is "+CPIN: READY" and
ModemManager is happy.
Using the AT interface manually, I can notice this behavior:
Directly after starting the modem, the answer to "AT+CPIN?" is "+CME
ERROR: 10", only after some 30 seconds, the answer is "+CPIN: READY"
I don't now the standards good enough, to judge if such behavior is
allowed, but I'm pretty sure, that this behavior is the problem for
ModemManager. When the answer to "AT+CPIN?" is "+CME ERROR: 10" once, it
marks the modem as failed without retrying.
I attach a complete log of ModemManager Debug output. ModemManager
starts, when the device is "hot", eg running for a while, so everything
is working. When the device is fully recoginzed by ModemManager, I
toggle the Reset pin of the modem which causes the restart of the modem,
the device disappeares from ModemManager, and after a while, when the
/dev/ttyUSBx devices appear again, ModemManager starts talking to the
modem, but get's errors, as it is too "early".
As I said, I don't know, if this behavior of the modem is acceptable
from the standard. Can someone comment about the behavior of the modem?
Should I get to the manufacturer, and tell them, they do something wrong
(and hope they fix it) or should ModemManager handle such a situation,
eg by retrying?
USt_IdNr.: DE 195663499
WEEE-Reg.-Nr.: DE 63967380
Sitz der Gesellschaft: Berlin
Registergericht: Amtsgericht Charlottenburg HRB Nr.: 67865
Geschäftsführer: Hans-Joachim Langermann, Malte Langermann
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