nRF91 Modem Updater using probe-rs

Summary

This is a tool to update the nRF91 modem firmware using the probe-rs crate. It provides both a CLI and library interface. Used in production on the nRF9160 Feather and nRF9151 Feather.

Validated working on:

• nRF9160
• nRF9151
• nRF9161

Getting Started

1. Install the Rust toolchain

Install Rust using rustup.

On macOS and Linux:

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

On Windows download and run the installer from rustup.rs, then open a new PowerShell or Command Prompt window.

After installation, confirm the toolchain is available:

rustc --version
cargo --version

2. Install with cargo

cargo install --git https://github.com/circuitdojo/modem_updater.git

This places the updater binary in ~/.cargo/bin (or the equivalent on Windows).

3. Install probe dependencies

Sometimes you may need to install dependencies. If your compilation fails here are some suggestions:

• Linux: ensure libusb-1.0 and libudev-dev are present (sudo apt install libusb-1.0-0 libudev-dev).
• macOS: install Homebrew and run brew install libusb if it is not already available.
• Windows: if necessary, use Zadig to install a WinUSB driver for your debug probe.

CLI Usage

To verify the modem firmware, run:

updater verify <path_to_firmware_zip>

To program and verify the modem firmware, run:

updater program <path_to_firmware_zip>

The CLI auto-detects the connected nRF91 target by reading the device part number. If raw debug access is unavailable, updater will attempt to restore access using the same nRF91 unlock flow as the companion recovery tool before continuing.

Developement

1. Install the Rust toolchain

Install Rust using rustup.

On macOS and Linux:

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

On Windows download and run the installer from rustup.rs, then open a new PowerShell or Command Prompt window.

After installation, confirm the toolchain is available:

rustc --version
cargo --version

2. Clone this repository

git clone https://github.com/circuitdojo/modem_updater.git
cd modem_updater

3. Build the project

Build a release binary locally:

cargo build --release

The resulting executable are located in target/release/:

• updater - Main firmware update tool

4. Target detection and recovery

The library and CLI support both nrf9151 and nrf9160 target profiles.

• updater auto-detects the target profile from FICR part information
• if debug access is blocked, updater first tries to restore access non-interactively
• if the device is still locked, updater falls back to the nRF91 CTRL-AP erase-and-reset flow

This split exists because the modem DFU bring-up sequence is not identical across the chips. In particular, UICR programming and IPC receive masks differ between the profiles.

Acknowledgements

This project is based on the work of @maxd-nordic in the pyOCD project.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT) at your option.