SIM card not detected in RAK8212

[espruino-discuss]

Posted at 2019-07-07 by alexfreed58

I'm trying to bring RAK8212 to life. Loaded Espruino and now I can use BLE and talk to the BG96 module using https://www.espruino.com/ide/. So far so good. I'm able to send AT commands with at.cmd() wrapper. The module replies as expected for the most part, but won't connect to a network. I tried 2 different SIM cards and it looks like the module just doesn't see them at all. I get error "10" to AT+CPIN? and other commands related to a SIM card. I have used a scope to see if there is any activity on the pins, and it looks like during a cold start the power is supplied to the SIM card for a while, even both 1.8 V and some higher voltage, but then the power is removed and not restored even when issuing a SIM related command.
Is it a hardware problem? Looks like it to me. I'm speculating that the BG96 module tries to talk to the SIM card even at 2 different voltages, gives up and powers it down thinking it's just not there. Alternatively I may have written some wrong stuff while experimenting with it. Any ideas? Thanks.

[espruino-discuss]

Posted at 2019-07-07 by alexfreed58

Well, to answer my own question, it WAS a hardware problem. One resistor was missing next to the SIM connector. Found a high enough res picture on the net showing that the resistor should be there. Problem solved. Now having to use wrappers for every command is a bit annoying. I don't speak java script. Is there a simple script that would just take strings from the serial or BLT interface, forward verbatum to the module and show whatever comes back?

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Posted at 2019-07-07 by Robin

Sun 2019.07.07

Hi @alexfreed58, glad your detective work located the missing part. Odd that the factory didn't catch that!

I have no experience with the RAK8212

Have the following been reviewed?

Many refer to this excellent @wklenk starter article:

https://wolfgangklenk.wordpress.com/2018­/09/13/espruino-on-rak8212-getting-start­ed/

Sample modem usage commands:

https://wolfgangklenk.wordpress.com/2018/10/12/espruino-on-rak8212-accessing-the-nb-iot-nb1-modem/

While at:

https://www.espruino.com/RAK8212

Type 'bluetooth' in the search box, loads of examples. . . .

> re: 'Is there a simple script'

May not be as simple as one would think. Do you have code that could be posted, at the points where it is desired to bridge for the output you are after?

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Posted at 2019-07-07 by @allObjects

Sometimes the driving side has pull-ups / pull-downs... and sometimes the driven side - on a data, clock or chip select/enable line. At least the manufacturer accommodated with pads for one to put on... (I assume it was one that kind of thing with the resistor...).

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Posted at 2019-07-11 by @gfwilliams

. Is there a simple script that would just take strings from the serial or BLT interface, forward verbatum to the module and show whatever comes back?

Something like:

Bluetooth.on('data', d=>Serial1.write(d));
Serial1.on('data', d=>Bluetooth.write(d));
LoopbackA.setConsole();

But you'll no longer be able to control Espruino unless you disconnect and reconnect. You can't use Serial because the nRF52 only has one serial port, which is needed for the modem.

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Posted at 2019-07-18 by alexfreed58

Pull up/down it was not. Zero ohm resistors, AKA jumpers are connecting the pins of the SIM card connector to the module. One was missing. Forgotten or not properly soldered and lost.

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Posted at 2019-07-18 by alexfreed58

Thanks, Gordon. I'll try it.