I had a problem that the module failed to find the SIM card. This seems to be a common problem for this chip.
- The module can be accessed via USB. The AT commands got delivered and replied.
- The VSIM card has no power, which is supposed to be 1.8 V.
Got error with SIM card related commands:
+CME ERROR: SIM PIN required
+CME ERROR: SIM failure
+CME ERROR: SIM not inserted
Here are similar posts about it:
- Sim Card not detected NB-IOT SARA N280-02B-00
- Network Connectivity Issue with SARA R410M-02B
- NB MKR 1500 - modem testing
Seems it is a common problem.
This was a hardware connection problem. I found that the
SIM_RST pin and the
SIM_IO short-circuited. Quite simple, right?
If you got a similar problem, check them with a multimeter first.
I have to say
The key point of this post is, I would like to criticize the LGA footprint design of the module. If you look at the footprint document, you will find that the space between each pin is just too small. If you solder this module like me in a modified toast oven, probably you will get this problem. The best practice is to follow the instructions Section 3.3 in “SARA-R4_SysIntegrManual_(UBX-16029218)”. You need a precisely controlled environment for its soldering process.
I sincerely hope that uBlox can design the footprint in a more robustly way. Anyway, the module is not cheap, and reworking nullifies all the warranty (as suggested by the manual).
How to Resolve
If you have a failure in using the module, melt it down from the circuit, clean it up, and try again. Another suggestion is to use a smaller pad to replace the original ones. And you may want to extend the pad to the outside of the module courtyard.
The uBlox SARA-R410M-02B uses a different pin assignment for the UART interface. The
TXD (Pin 12) is actually for reception on the SARA module, and the
RXD (Pin 13) is the transmitting pin. I haven’t noticed this on my version 1.0 board, then I had to make an updated version.
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