sometimes when trying to register to the network the GE865-Quad seems to perform a reset.
Every two seconds an AT+CREG? command is send to the GE865. Sometimes there is no response for a few seconds and afterwards the GE865 echoes the command before sending +CREG: 0,2
But the echo has been turned off before by sending ATE0.
What might cause this behaviour?
I would say the module does a full hardware reset because of insufficient power when trying to register, maybe only marginal, hence is doing only sometimes.
Is there a way to verify that it is a hardware reset?
Monitor PWRMON, and if you have good tools you can investigate when and how much power voltage drops.
I checked PWRMON using an oscilloscope but I did not see a falling edge on that line.
PWRMON remains high after powering the GE865.
One additional thing I have seen right now is that after a successfull registration I tried to send a sms but I got CMS ERROR 311 and later CMS ERROR 310.
But the SIM is inserted properly.
I would still say you have power problems, with that silence on serial port and setting forget . Put lines to status LED, test network etc.
Is your hardware or an EVK module?
It is a hardware made by ourselves.
I have just received a hardware desgin review report from Telit five minutes ago.
Here are some hints, maybe you can figure out if there may be connection with the problem I experience.
2.1. Schematic review
2.1.1. Power supply
o You should remove R44: the VRTC pin of GE865 brings out the Real Time Clock
supply, which is separate from the rest of the digital part, allowing having only RTC
going on when all the other parts of the device are off. To this power output a backup
capacitor can be added in order to increase the RTC autonomy during power off of the
2.1.2. SIM pins
o R24 must be removed otherwise the module could be damaged.
o The value of C82 should be changed from 10pF to 1uF.
2.1.3. Digital pins
o The SERVICE pin of GE865 is used to upgrade the module trough the auxiliary serial
port and should be routed just to a test pad.
2.1.4. Audio pins
2.1.5. RF aspects
o Add a 33pF capacitor to ground as close as possible to VBAT pins of GE865.
And a new behaviour:
I have monitored the communication between my host processor and the GE865.
The output is all printable characters in their ASCII representation all control characters as HEX code in brackets. For example <05> means a character with the hexadecimal value 05 has been received. <0A> is a linefeed, <0D> is a carriage return.
here is the result:
HOST -> AT+CREG?<0D>
GE865 -> <0D><0A>+CREG: 0,2<0D><0A><0D><0A>OK<0D><0A><00>
HOST -> AT+CREG?<0D>AT+CREG?<0D>AT+CREG?<0D>AT+CREG?<0D>
GE865 -> <92><00><00>
and so on…
Any ideas what this means?
Along already mentioned, hardware problems on serial lines, baudrate mismatch. Do yourself a favor, strengthen your hardware and test it first with a serial link to a PC with a reliable serial terminal software.
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