Unable to downgrade nRF9160 modem firmware from 1.0.1 to 1.0.0

[Jleguen]

Hi,

I'm trying to downgrade the nRF9160 modem firmware from 1.0.1 to 1.0.0. I'm currently unable to connect to LTE network from a location where I was connecting in seconds beforehand. This is critical because even in locations where the LTE network is around -60dBm (measured with my phone) the modem does not connect.

Re-flashing the 1.0.1 works flawlessly so this is not an issue with my software configuration.

When trying to downgrade with nRFConnect I get the following log :

2019-10-22T16:30:48.533Z INFO Recovery procedure finished
2019-10-22T16:30:48.547Z INFO Using nrfjprog to communicate with target
2019-10-22T16:30:50.188Z INFO Using J-Link Software version 6.48
2019-10-22T16:30:52.318Z INFO Segger serial:  600114712
2019-10-22T16:30:52.319Z INFO Segger speed:  2000  kHz
2019-10-22T16:30:52.319Z INFO Segger version:  J-Link V10 compiled Jul 23 2019 13:46:10
2019-10-22T16:30:52.328Z INFO Probed: 600114712.
2019-10-22T16:30:52.328Z INFO Model: NRF9160_xxAA_FUTURE.
2019-10-22T16:30:52.328Z INFO RAM: 256KiB.
2019-10-22T16:30:52.328Z INFO Flash: 1024KiB in pages of 4KiB.
2019-10-22T16:30:53.784Z INFO Reading device non-volatile memory. This may take a few seconds.
2019-10-22T16:31:07.457Z INFO Modem DFU starts to write...
2019-10-22T16:31:07.457Z INFO Writing to device with serial number: 600114712
2019-10-22T16:31:07.457Z INFO Writing to device with file: E:\nordic\modem_upgrade\mfw_nrf9160_1.0.0.zip
2019-10-22T16:31:09.589Z INFO Checking file 1 of 7 files.
2019-10-22T16:31:09.590Z INFO Finished with file.
2019-10-22T16:31:09.593Z INFO Checking file 2 of 7 files.
2019-10-22T16:31:09.595Z INFO Finished with file.
2019-10-22T16:31:09.597Z INFO Checking file 3 of 7 files.
2019-10-22T16:31:09.605Z INFO Programming file.
2019-10-22T16:31:09.637Z INFO Programming 1 of 1 segments.
2019-10-22T16:31:09.728Z INFO Programming finished.
2019-10-22T16:31:09.731Z INFO Finished with file.
2019-10-22T16:31:09.735Z INFO Checking file 4 of 7 files.
2019-10-22T16:31:09.738Z INFO Programming file.
2019-10-22T16:31:14.423Z INFO Programming 1 of 33 segments.
2019-10-22T16:31:14.873Z ERROR Modem DFU failed with error: Error: Error occured when program. Errorcode: CouldNotCallFunction (0x9)
Lowlevel error: Unknown value (ffffff23)

What solution do I have to get my modem to work again?

Thanks

[Martin Lesund]

Note: it is not possible to downgrade to previous modem firmware releases after applying this upgrade.

So you were able to connect to the LTE-M network without any issues with the nrf9160 with the mfw v1.0.0?
Are you using the iBasis SIM card or local carrier SIM card?

Please share the LTE link monitor log from when you are trying to connect and it would be nice if you could share a modem trace then we can figure out what is going wrong.

[Jleguen]

Hi,

I finally figured it out, somehow the MAGPIO table got flushed and the RF switches on the board were not properly configured... Well that will teach me not to rely too much on the non-volatile storage :)

Thank you for the help!