SigCell M1-N1 FAQ

Some of the frequently asked questions about SigCell M1-N1 are answered below.

Why is the device rebooting every second?

Device exhibits this behavior when the modem firmware is not programmed into the module.

If you had already programmed the modem firmware, this could happen if the modem firmware is not healthy. This may happen during development only.

When this happens API UART would print the startup message, such as below, every second

+notify,event:init,result:0,firmware:v1.0.8

The solution is to update the modem firmware. Download the modem firmware from Nordic. Use nRGF Connect Programmer to `Update modem`

Please contact support if you need help with choosing the modem firmware version to use, or programming the device.

How can I programmatically query SIM serial number?

SIM ID can be queried by issuing an AT command. AT%XICCID

You can issue AT command like this

+set,at:AT%XICCID

Expected result will be like this

+rsp,at:%XICCID: 89148000005402711360

What AT commands are supported apart from the SigNet API?
Nordic AT command set is supported.

AT command reference guide for the nRF9160 on SigCell can be found here

Note: usage syntax is 

+set,at:<AT COMMAND>

eg: 

+set,at:AT%XICCID

How to query cellular signal strength?

See API document for usage of property: cell_rsrp

How should cell_rsrp return value be interpreted?

Value returned by cell_rsrp represents the cellular signal strength.

This number is RSRP with 140 added to it so it is always positive. A larger number is better and should be similar to the chart here:

 

https://customer.cradlepoint.com/servlet/rtaImage?eid=ka938000000L0ML&feoid=00N38000003lF9E&refid=0EM38000000HpD4

 

So, 30 would be -110 which is fair.

45 is -95 which is good.

55 is -85 which is excellent.

 

NOTE: cell_rsrp=255 represents inability to get a signal strength. Typically this happens when the module is not connected to the network.

How to query whether device is connected to cellular network ?

See API document for usage of property: connected

Can some properties be saved to Non-Volatile memory and restored at startup?

Yes. The following properties can be saved to NV memory. For an explanation of these parameters, see SigNet API documentation.

devid
nbiot
devtype
fotahost
fotahostname
proto
autoconnect 
enabled
serv_address
serv_port
sectag
user 
pw 
polltimeout
queue1 
queue2 
queue3 
queue4 
queue5 
subtopic1
subtopic2
subtopic3
subtopic4
subtopic5
pubtopic

To save the properties after setting / modifying, a "save" command is required.

usage:

+set,saved:1

What does the LED color indicate?

LED on the SigCell M-N1 starts red when powered up, It will turn blue when it is attempting to connect to network and bootstrap. Once the network connection is established and the device is ready for user application, LED will indicate signal strength level with yellow/green/purple.