Question about the modem in IoT Starter Kit gen 2

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thaitran's picture
thaitran
Junior(0)

Hi,

We're building a power meter with networking capabilities and have selected the wnc m18q2fg-1 modem as our modem of choice. We've designed our own PCB following the data sheet and I'm in the process of getting the modem up and running with our linux single board computer. I contacted avnett for technical support and was eventually refered to this forum. The modem part# is wnc m18q2fg-1

I'm having some problem with the modem as explained below:

We built a carrier board for the modem and this is plugged into a single board computer. The single board computer recognized the modem and it showed up as an usb ethernet device. However, I could not get it to recognize any sim card. 

I've checked our sim detection signal and it seems to be working correctly, sending 1.8V to to modem when a sim is inserted. However, the modem does not produce a Sim VCC to power up the SIM card.

Can anyone tell me what might be wrong ?

 

 

thaitran's picture
thaitran
Junior(0)

I can't post any link or make any edit since the system consider it as spam??? But if you need a look at the schematic please let me know where I can send it to. The modem we're using is the same modem that is used in the IoT kit gen 2

Thanks

jflynn129's picture
jflynn129
Moderator(4)

Hi, can I get some additional info on the setup if possible.Do you know what version of firmware is loaded into the M18Q device?  I am assuming that you have been able to interact with it, can you confirm that for me.  

 

thaitran's picture
thaitran
Junior(0)

Hi,

we're designing our own circuit board and follow the instruction in the data sheet. Only USB connection is wired for the modem. I can establish connection to the modem using AT command, but status check using AT+CPIN? just return a SIM not inserted error. I'm not sure how to get the firmware version from the device. Can you give me an email address so I can send you our circuit schematic, I can't attach any picture or link here.

Thanks

PeterF's picture
PeterF
Moderator(16)

Thai, I recommend taking a look at the schematic for our M18Q2FG-1 based SOM board. This is located under the documentation section of AT&T IoT Starter Kit (2nd Gen.)  http://cloudconnectkits.org/product/lte-starter-kit-2

 

Here is the direct link for the schematic download:
http://cloudconnectkits.org/sites/default/files/att-m18q2fg-m1-g_RevD.pdf

 

PeterF's picture
PeterF
Moderator(16)

The firmware version can be checked using the ATI command, from the M18 modem interface

eg. here's the response I get (for WNC host-mode, latest version of firmware) to an ATI command

 

ATI
Manufacturer: WNC
Model: M18Q2FG-1
Revision: MPSS: M18Q2_v12.09.182151 APSS: OE_v01.05.182421 CUSTAPP:

 

Alternatively, if you download and install the WNCCM tool this will also report the firmware version (and is the tool that you use, if needing to upgrade the WNC firmware). This available from the AT&T QuickStart webpage: https://marketplace.att.com/quickstart

 

thaitran's picture
thaitran
Junior(0)

Hi,

Thank you for the reply, I was able to check the firmware version, currently the modem has revision MPSS:M18Q2_v12.09.163431 on it

 

I also compared our schematic to the one you provided and it looks like the value of our pull-up resistor is too high. We're re-using the pull-up value from the circuit for the WNC LTE CAT1 modem which is 422kOhm vs 10kOhm in yout schematic. This might explain why our SIM card is not detected.

 

PeterF's picture
PeterF
Moderator(16)

The attached PDF file shows the SIM card interface on the WNC HDK board

thaitran's picture
thaitran
Junior(0)

I've replaced the pull-up the resistor from 422 kOhm to 10 kOhm but still getting the same problem. The modem powered on, respond to AT command but did not detect that a SIM card was inserted, when I sent the at+iccid command it reported as SIM failure. Do you have any other suggestions on what might be wrong with our modem or why our SIM cards are not being recognized?

Thanks

PeterF's picture
PeterF
Moderator(16)

Thai

 

An in-depth response to your issue has been sent to your email address. Please send your schematic privately for review

 

Regards

Peter