https://github.com/andrasbiro/grubswitch

Raspberry pi pico based physical GRUB select switch
https://github.com/andrasbiro/grubswitch

grub grub2 mass-storage mass-storage-device raspberry-pi-pico rp2040 rp2040-zero usb-mass-storage

Last synced: about 7 hours ago
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Raspberry pi pico based physical GRUB select switch

• Host: GitHub
• URL: https://github.com/andrasbiro/grubswitch
• Owner: andrasbiro
• License: mit
• Created: 2024-10-21T18:43:40.000Z (17 days ago)
• Default Branch: main
• Last Pushed: 2024-10-24T16:50:09.000Z (14 days ago)
• Last Synced: 2024-10-25T23:55:35.867Z (13 days ago)
• Topics: grub, grub2, mass-storage, mass-storage-device, raspberry-pi-pico, rp2040, rp2040-zero, usb-mass-storage
• Language: C
• Homepage:
• Size: 124 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# GRUB switch

This is a simple physical switch to control GRUB2 inspired by a [simplar project

for STM32](https://github.com/stecman/hw-boot-selection), but implemented on the

Raspberry Pi Pico (developed on RP2040-Zero, but any Pico should be good).

The code is using an SPDT On-Off-On switch, one side selects Linux, the other

Windows, while in the middle selection, the GRUB menu stays on indefinately -

but this should be very easy to modify.

I needed this, because I have a strange dual boot setup where my monitor usually

turns on with the input that is not the default from my UEFI setup.

A 3d printable case is also available in the case folder, with Fusion 360 design

files.

## Build and install

An uf2 binary is available as release for easy testing.

Install the [pico-SDK](https://github.com/raspberrypi/pico-sdk), cmake and

arm-eabi-gcc.

Make sure to set the environemnt variable PICO_SDK_PATH to point the folder

where your pico-SDK is (e.g. `export PICO_SDK_PATH=/usr/share/pico-sdk`).

Then continue with the usual cmake setup:

```bash

mkdir build

cd build

cmake ..

make

```

Finally, install the generated `build/grubswitch.uf2` on the Pico. It will

reboot as a FAT16 drive, labeled "GRUB-SWITCH".

The switch should be connected to pin28 and pin29 if the code is used

unmodified.

## Setup GRUB

Copy [49_switch](49_switch) to `/etc/grub.d`. Modify the entry numbers

highlighted with comments. Make sure it's executable and run `update-grub` as

root.

## Modification

The letters set by the switch are defined in [msc_disk.h](src/msc_disk.h). The

switch is read in [main.c](src/main.c). The filesystem and filename are defined

in [msc_dis.c](src/msc_disk.c) - although I wouldn't recommend changing this

unless you have to.

## Inspiration

This project was developed based on the following:

* [The ST implementation of the same

  idea](https://github.com/stecman/hw-boot-selection)

* [Another pico

  implementation](https://www.hackster.io/Madrajib/hardware-boot-select-switch-using-pico-a3e3d5)

  I just didn't like that it's a documentation on how to modify an example

* [A nice demonstration project of USB

  MSC](https://github.com/brendena/pico_drag_n_drop_programmer) with a lot of

  links and explanation video.