15 April 2019 at 3:44 AM #37571
I am trying to work with this new raspberry pi modem HAT. Currently I am attempting to work the modem with my computer through USB and putty. I can send and receive commands through serial but nothing I do gets the modem to see RF signals or register the SIM. The test setup is as follows:
1. Connected bench top PSU to the board capable of supplying up to 5 amps at 5 volts. (it draws about 80mA when its on and searching for signal, 50mA when idle). This should eliminate any under current issues.
2. Connected a large 4G LTE CradlePoint brand antenna to the LTE port on the board. I have also tried several times with the Sixfab supplies Pulse Electronics one. I am also in an area with excellent AT&T 4G LTE signal.
3. Connected the Sixfab board to my computer through the micro USB cable and started a terminal session.
4. I turn on the power, wait 10 seconds then press the “pwrkey” button for 3 seconds. This wakes up the modem and then I can see the COM port display in my device manager. I then connect to the device through putty at a baud rate of 115200bps.
5. Ensured that the AT&T SIM I am using is active. It is a Data only line with a private APN and static IP. I tested this SIM in two separate 4G CradlePoint modems and it works fine.
Serial log with notes (#)
# I set echo on
# I set error codes to verbose
# display product info, modem mnfc, model, revision
# Quectel modem IMEI number
# display status of the SIM. Ready indicates it does not require a PIN
# query the initialization status of SIM card. (e.g. 3=1+2 means CPIN READY & SMS DONE).
# display SIM card number
# display SIM International Mobile Subscriber Identity number
# display phone functionality. 1 = Full function
# display Signal Quality Report. RSSI and BER = Not known or not detectable
# Network registration status – Disable network registration unsolicited result code & Not registered, but MT is # currently trying to attach or searching an operator to register to.
# Network Registration Status – Disable network registration unsolicited result code & Unknown
# EPS Network Registration Status – Disable network registration unsolicited result code & Not registered, but MT is currently trying to attach or searching an operator to register to.
That’s as far as I have gotten. Any ideas?
Kyle.18 April 2019 at 11:01 AM #37642
Something else I thought of is that the CEREG or CGREG (packet switched) will not be able to complete until CREG (circuit switched) completes with x,1 or x,5.
Paul18 April 2019 at 11:04 AM #37643
this was the first response but forum is wonky ever since I tried to edit.
This forum keeps complaining and not posting because I tried to edit. This is an effort to fool the dupe detector.
You are on the right path. You have already done most of the important bits. One would actually expect it to probably work at this point…
The problem I’ve seen on some of these BG96 modules is that default values are not always set the way the manual says. It depends on which flavor of FW is loaded on the module.
I would suggest you check
and specifically set
so that operator selection is automatic.
If you want to know what networks are available in your area you can run
AT+COPS=?and wait for a while.
Furthermore, I have seen that the sixfab code does not always set all of the config (specifically QCFG) settings needed. I recommend
AT+QCFG=”band”, 0F, 400A0E189F, A0E189F, 1
You can tweak these depending on if you want 2G only or 2G, CatM1, NB-IoT, etc
You will not get a useful CSQ back until you are registered on a tower to an operator. CREG will return x,1 or x,5 and COPS? will return non-0.
Let us know if that works for you.
Paul18 April 2019 at 2:31 PM #37661
Thank you for your answer.18 April 2019 at 6:53 PM #37678
I found the issue. Here is what I ran:
# Search for available operators. Waited 20 minutes. This command never resolved, had to reset the modem.
# Set operator selection to automatic
# RAT(s) to be searched. Default scan mode is in Automatic
# Specifies network category to be searched under LTE RAT. The Documentation does not list -1 as an accepted value, only 0,1,2.
# Specifies searching sequence of RAT. Default set to search LTE Cat NB1, M1, then GSM.
# Sets the allowed RF bands to be searched. I switched these from the default values (0x1,0x10,0x80000) to the following:
For At&t, these bands are of interest:
The value in AT+QCFG=”IOTOPMODE” seemed suspect. The documentation makes no note of “-1″ value. When i changed this to 0 through the following command (AT+QCFG=”IOTOPMODE”,0,1) It connected immediately!
Thank you for your help! Going into this I knew nothing about modem AT commands. Now I think I’m getting the hang of it.18 April 2019 at 7:07 PM #37680
Glad that helped.
iotopmode of -1 is nothing I ever heard of. Curious where you got that or saw that listed?
For sure, if you are attempting to connect to LTE (not 2G) then you will need iotopmode set properly. There is some evidence that the BG96 does not always contain proper default settings AND some settings are not persisting like they should.
Now that you have the settings correct, you should be able to run ‘AT+COPS=?’ in order to see the available operators. Typically it will return in <5 min but it can take quite a while to scan all of the bands and modes.
To my knowledge the only CatM1 you will see in the US is AT&T and Verizon, and in some places T-mo is deploying NB-IoT. It will vary by area.
Paul22 April 2019 at 11:15 AM #37710
Thank you Kyle and Paul for sharing your experience and knowledge.
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