SARA R4 410M 02B with Telia SIM card does not respond after boot if pin code check is disabled

I have the following issue:

Telia SIM card with pin code check disabled => SARA R4 410M 02B boots up with only one serial port on the USB interface, it is not responding to AT command either on USB or UART interface.

Telia SIM card (same card) with pin check enabled boots ok, and the pin can be set via AT commands on the second serial channel that is enumerated.

This is tested both with the modem connected to a Linux host machine and also in our embedded system with usb driver from HCC embedded.

The same SIM card works fine in both cases with the N211 modem.

Has anyone seen the same issue?

Dear @monalisan,

Do you use the same sketch for the N2XX and R4XX?
Both modules need a different baudrate and the R4XX need to set an extra pin.

See this sketch:

Kind regards,

Hi Jan,
Yes I have programmed the boards with different sketch, 9600 for N211 and 115200 and the extra pin for R410.
i have also soldered the USB cable to the R410 to get access to the USB interface.

I found the problem for this issue. In the pass trough sketch, the voltagePin need to be low for a period of 0.15 s min ā€“ 3.2 s max.
So I inserted the code below:
#ifdef R4XX
// Switch module voltage
pinMode(voltagePin, OUTPUT);
digitalWrite(voltagePin, LOW);
digitalWrite(voltagePin, HIGH);

After this change the modem starts up enumerate on USB as it should, with both enabled and disabled pin code check.
Best Regards

1 Like


I am glad you have a fix for now.
What ublox firmware version do you use?

Best regards,


Iā€™m using the latest, i.e
Model: SARA-R410M-02B
Revision: L0. [Feb 03 2018 13:00:41]

And the behavior of the PWR_ON pin is described in Ublox System integration Manual: UBX-16029218 - R10.

Best Regards