Serial LTE modem code don't start

[Alban THIERRY]

Hi everyone !

I have a strange issue, when I flash : nrf9160dk_at_client_2024-07-12_5cb85570.hex on our board the code is running normally. But when I flash nrf9160dk_serial_lte_modem_2024-07-12_5cb85570.hex the code don't start on some board. The nrf chip never send Ready on the bus even when the RTS and CTS are down.

Do you know the difference between the 2 code at the startup ?

To flash the firmware I'm using programmer V4.4.0 I also flash mfw_nrf9160_1.3.6.zip.

Best regards,

Alban

[dejans]

Hi,

Do you use your own custom board with nrf9160?

But when I flash nrf9160dk_serial_lte_modem_2024-07-12_5cb85570.hex the code don't start on some board.

How many boards have you tried to flash this hex file to?
Was flashing successful on some boards?
Did you try flashing using Programmer application?

Best regards,
Dejan

[Alban THIERRY]

Hi Dejan,

By custom board I mean that we develop our own PCB with the NRF9160 this is the schematic (the board is power at 3.3 volt): 

We have 8 board and only 2 is working serial lte modem is working. What I mean by working is that when I power up the board the NRFchip send Ready on the uart. On the other hand when I flash AT client code all the board start up and send me ready on the uart bus.

Yes all the flashing is successful. What I do is first erase, the erase an write the fw (serial lte modem or) then write the mfw_nrf9160_1.3.6.zip

I only flash using programmer V4.4.0 :

Best regards,

Alban