NRF9151 replaces NRF9160: LTE not working any more

RE: NRF9151 replaces NRF9160: LTE not working any more

AraNRF91 — Tue, 24 Jun 2025 04:30:11 GMT

so after a long try-and-error path, refactoring the modem lib and manual analysis of the traces i got the NRF9151 working with LTE again:

Make sure any AT search commands are off as at starting the lib mine tried to search for nearby towers and then when you use "CFUN=1" for full-conn and try to connect, the search param strictly prohibit the modem to connect to any cell. Therefore by (forcefully) disabling any search and then trying a reconnect, i finally got to re-attach my network successfull, with repeated and verified checks. And with CFUN=1 the CGATT ist automatically started, do not try to do both AT commands as those could conflict on the modem too. So in short:

AT+CFUN=0       // Set functionality mode off to configure
AT+COPS=0       // Automatic operator selection
AT%XSYSTEMMODE=1,1,0,1      // Set system mode preferences
AT+CGDCONT <APN-Config>     // Set APN Config
AT+CGAUTH <username, password>      // if used pass auth data
AT+CPIN <pin>       // if used add SIM Pin
AT+CFUN=1       // activate the modem
loop {
  AT+CGATT        // loop this until connected and returns 1
  ...

To verify your modem is ready and antenna and other hardware are intact and functioning, i used the "AT+COPS=?" to get a full list of all surrounding cell towers. Try that before digging too deep into the code while the hardware could be bogged.

This was my "final frontier" for this problem. On the way i adjusted many more options and measurements which you can read through in this chat, in the problem description or the public Rust driver.

RE: NRF9151 replaces NRF9160: LTE not working any more

Hakon — Mon, 23 Jun 2025 10:24:58 GMT

[quote user="AraNRF91"]i gathered the modem trace as mtrace and the regarding full log again here:[/quote]

Thanks, what modem firmware is this captured with?

RE: NRF9151 replaces NRF9160: LTE not working any more

AraNRF91 — Wed, 18 Jun 2025 08:16:47 GMT

i gathered the modem trace as mtrace and the regarding full log again here:

nrf9151_lte_example_nRF9160_xxAA_1750233445688_channel0.mtrace

nrf9151_lte_example_nRF9160_xxAA_1750233445688_channel0.txt

as i experimented further with the modem and AT commands i found, that using "AT+COPS=?" for searching operator cells nearby draws 6 times the usual current but while setting CFUN=1 and waiting for attach the modems power draw does not change in comparison to CFUN=0? Are there any other commands or functions to be activated to power on the modem for CFUN=1?

Also while working on a improved lib with extended tracing and capability to extend the AT usage, we found that only very few already have a NRF9151, which is why approving and verifying is certainly very hard. We will get a nrf9151-DK to test on it in the next weeks.

RE: NRF9151 replaces NRF9160: LTE not working any more

Hakon — Fri, 06 Jun 2025 09:10:20 GMT

Can you please provide a modem trace in the format .mtrace or .bin?

RE: NRF9151 replaces NRF9160: LTE not working any more

AraNRF91 — Fri, 06 Jun 2025 08:10:54 GMT

i created a full log from starting the lte test application with setting up IPC and configuring everything for the modem to the whole "wait for lte connection" until the timeout after 60secs; it also includes the modem trace, marked with "modem trace:" as well as the libraries modem traces.

As the log is too big for posting it here, i added it at lte_standalone_nRF9160_xxAA_1749196801820_channel0.txt

RE: NRF9151 replaces NRF9160: LTE not working any more

Hakon — Thu, 05 Jun 2025 12:18:02 GMT

What should be included in the modem trace is everything from start to finish of a network search. We need to see what is happening when the modem is unable to find the network.

RE: NRF9151 replaces NRF9160: LTE not working any more

AraNRF91 — Thu, 05 Jun 2025 12:14:40 GMT

that would be great. What should be included in the modem trace? i can toggle there trough various options in the lib

RE: NRF9151 replaces NRF9160: LTE not working any more

Hakon — Thu, 05 Jun 2025 11:29:45 GMT

Okay, it is hard to say exactly why your modem does not connect. A lot of the changes are internal information and can not be shared publicly. If you can provide a modem trace, I will ask the modem team for assistance.

RE: NRF9151 replaces NRF9160: LTE not working any more

AraNRF91 — Thu, 05 Jun 2025 04:33:02 GMT

Hello Hakon,

thanks for your reply.

The antenna/RF design was adjusted by our hardware engineer according to the documents provided with the nrf9151.

And the list of changes from nrf9160 to nrf9151 to get it halfway working:

UICR:

/// Ensures that the UICR registers that control the HF clock source
/// are properly initialized. On the nRF9151, the modem expects to use the internal oscillator,
/// so HFXOSRC must be 0. If the registers are erased or misconfigured, they are updated
/// and the system resets to apply changes.
let so = unsafe { read32(UICR_BASE + HFXOSRC_OFF) };
let co = unsafe { read32(UICR_BASE + HFXOCNT_OFF) };
let bad = so != 0 && so != 0xFFFF_FFFF;
let erased_so = so == 0xFFFF_FFFF;
let erased_co = co == 0xFFFF_FFFF;

if bad || erased_so || erased_co {
    warn!("Fixing UICR");
    ... set UICR values

set HfclkSource and LfclkSource to internal RC clock as it would otherwise look for a external RTC
then comes initialising the modem and network
- init IPC Mem at 0x2000_0000 and init modem and network driver with the embassy_net_nrf91::new lib
- spawn modem task for IPC and state management
- spawn net task for network I/O with default driver settings and 8 available sockets
- spawn control task to set APN+Pin
- getting some Modem/Sim Infos to verify connection (AT+CGMM, AT+CIMI, AT%XICCID)
- after that i call "wait_config_up" of the library, as this attaches the modem to the LTE network and then responds with a result if we get a connection with IP+DNS from the provider. At this point the nrf9151 runs eternally without any connection. the nrf9160 with the same setup and Sim gets one.

And changes done in the embassy_net_nrf91 lib:

verifying SHMEM/SPU Region size at init for length be 8kb-aligned & greater 0 & in the lower 128kb of RAM
adding a variable RX Control length and RX Data length. Those were hard written for 16b for the nrf9160 but with the nrf9151 we got 32b. Now the lib reads the lengths from the modem itselfs and uses the provided ones, either 16b or 32b
adding trace logs for AT notifications of the modem

I hope this helps in understanding the changes. One of the open questions is still if other things changed in the process? I worked trough the Modem logs, Documentation and nrf-modem-lib.c but could not identify any other related changes.

Also i will clean up the provided patch today to make it easier to verify

RE: NRF9151 replaces NRF9160: LTE not working any more

Hakon — Wed, 04 Jun 2025 16:45:07 GMT

Hello,

there are a lot of changes from the nrf9160 to nrf9151. Have you checked the antenna/RF design? The nrf91x1 use a different modem firmware than nrf9160. You have not provided much information other than linking to a 3rd party Rust driver, so it would be nice if you could tell more about what you have done.