Game and Watch Backup and Restore tools

This repository contains pre-built tools for backing up & restoring the original Game and Watch firmware. Both the Mario and Zelda variants are supported.

What you'll need:

• A Limited Edition Game & Watch, either the Super Mario Bros. edition released in 2020 or The Legend of Zelda edition released in 2021 in their original state
• An ARM debug probe (Tested with J-Link and ST-Link compatible devices), a Raspberry Pi, or a CMSIS-DAP debugger like a Raspberry Pi Debug Probe/Picoprobe or a Flipper Zero
• Connections to the debug port - testclips or soldered wires work well!
• A computer running Ubuntu 20.04 or compatible Linux distro. You can also use a Virtual Machine such as Virtual Box under Windows or MacOS.

Also see this video for a rough overview over how the scripts work: https://www.youtube.com/watch?v=-MzmoEFs0bQ

Warnings & disclaimer

The tools in this repository will modify both the internal and the external flash of the Game and Watch. While we tested the scripts to our best ability, we can not guarantee that there won't be failures that will leave your Game & Watch damaged. Use these tools at your own risk. If you feel like you don't understand what you're doing it might be best to let someone with more experience help (and teach) you! Feel free to join our discord channel and ask any support questions in #game-and-watch-support. You can also checkout the reddit community with over 2000 Members

Connecting the debugger

When connecting the debugger ensure that at least SWDIO, SWDCLK and GND are connected. Do not under any circumstances connect 3.3V to the VDD connection. If your debug probe (for example ST-Link clones) does not have a VTREF connector, just leave VDD unconnected. Connecting 3.3V to VDD will likely destroy your SPI flash.

The debug connector of the Zelda variant shares pinout with the Mario variant, but has two extra connections (PB3 and N/C). The small triangle points to pin 1.

Supported Debuggers

For best results please either use a full sized official ST-Link or a STM32 Nucleo device (not one of the small USB stick clones which can be hit or miss), a full-size J-Link debug probe, or a CMSIS-DAP debugger like a Raspberry Pi Debug Probe/Picoprobe or a Flipper Zero. There are others that work, but many of them do not work with the 1.9V logic levels used on the Game and Watch.

Programmers some users have reported having trouble with are: J-Link EDU Mini, cheap ST-Link clones (with the later likely do to changing pinouts or different chipsets).

Raspberry Pi host

You can use a Raspberry Pi to back up your Game and Watch. In this case you should use a Raspbian install and follow the steps in the Ubuntu setup section but on Raspberry Pi. You need to use 3 wires: GPIO25 for SWCLK,GPIO24 for SWDIO and GND for GND (in BCM pinout notation) or you can hardcode your own gpios in openocd/rpi.cfg. A quick pinout reference on RPi can be seen by opening a terminal and running pinout.

Raspberry Pi Debug Probe and Picoprobe

You can use a Raspberry Pi Debug Probe or self-assembled Picoprobe. Both run the same firmware and implement the CMSIS-DAP protocol. The Debug Probe has a connector attached to three male header pins. The orange wire is SWCLK, black is GND, and yellow is SWDIO.

Specify cmsis-dap as the adapter type when running the scripts from this repo.

Flipper Zero

You can use a Flipper Zero and its DAP Link app. As of firmware version 0.89 and newer, you will need to install the DAP Link app on your Flipper Zero through its companion mobile app.

How to install the DAP Link app

Pair the companion mobile app with your Flipper Zero. In the mobile app, go to the app directory on the "Hub" tab. Find the "GPIO" category, browse for the "DAP Link" app inside it, and tap "Install".

From the Flipper Zero's main menu, navigate to Apps → GPIO → DAP Link. The DAP Link app has a Config menu that specifies which of the Flipper Zero's GPIO pins correspond to SWC (SWCLK) and SWD (SWDIO). The pins are also documented under "Help and Pinout" in the Config menu. Use one of the Flipper Zero's GPIO GND pins to connect to GND on the Game & Watch.

Specify cmsis-dap as the adapter type when running the scripts from this repo.

Ubuntu setup

Install the required tools (Press "Y" for yes, if/when asked "Do you want to continue" and press the "Enter" key):

sudo apt-get install git binutils-arm-none-eabi python3 libhidapi-hidraw0 libftdi1 libftdi1-2

Clone this repo with submodules:

git clone --recurse-submodules https://github.com/ghidraninja/game-and-watch-backup
cd game-and-watch-backup

Note: The version of openocd included in Ubuntu 20.04 (0.10.0) does not include functionality that is needed by these scripts. A build from the unreleased master branch is needed. Please install a newer version either by building it yourself, or by installing a prebuilt package, e.g. from this nightly build, using xPack or similar.

Alternative openocd location

If you used the aforementioned nightly openocd build, it will reside in the /opt directory as shown below.

To use that specific version you can either export the variable OPENOCD or prefix your commands with the variable declaration:

export OPENOCD="/opt/openocd-git/bin/openocd"
./1_sanity_check.sh
./2_....

OR

OPENOCD="/opt/openocd-git/bin/openocd" ; ./1_sanity_check.sh
OPENOCD="/opt/openocd-git/bin/openocd" ; ./2_....

Finally, you could just hardwire some variables in the 'config.sh' file.

Mac Setup

Using homebrew:

brew install --HEAD openocd
brew tap ArmMbed/homebrew-formulae
brew install arm-none-eabi-gcc

Usage

Before starting, make sure to unplug the battery as it can interfere with the process. Power the device using the USB-C connector.

The scripts are split into 5 parts:

• 1_sanity_check.sh - Performs sanity check and makes sure all required tools are available
• 2_backup_flash.sh - Backs up the contents of the SPI flash. Does not modify device contents.
• 3_backup_internal_flash.sh - Backs up the internal flash. To do this the contents of the SPI flash are modified. Your device will stop working until it's restored in step 5.
• 4_unlock_device.sh - This will disable the active read protection. This will erase the internal flash of the STM32.
• 5_restore.sh - This will restore the original firmware.

Just run these scripts from the checked out directory one after each other. All scripts are safe to be re-run in case of error.

Ensure that you keep your backup in a safe place so you can always recover. Don't ask us for flash dumps & co, we will not share them.

What if something goes wrong

As long as your electrical connections are right and you didn't short/overvolt anything, chances are high that it's rescuable:

If a script fails and the device does not work after power-cycling, repeat the script. If it fails again, try to hold the power button of the device while executing the script.

Also, as a first step, try to lower your adapter speed. When using stlink, you do this by adding adapter speed 100 as the last line in openocd/interface_stlink.cfg.

Something goes wrong during Step 1 & 2

Your device was not modified by the scripts, so it should just continue to work after a power cycle.

Something goes wrong during Step 3

Step 3 will change the internal flash of the device. If this step fails it will leave your device in a bricked state. To recover from it run:

./restore_only_external_flash.sh <stlink or jlink or rpi> <mario or zelda>

If the script can't connect to the device, press & hold down power on the device while running flashloader & try to FULLY powercycle the target between attempts.

Something goes wrong during Step 4

Step 4 will cause a mass erase, and leave your device empty. To restore it, run script 5.

Something goes wrong during Step 5

Step 5 should succeed, if it doesn't: Try to run the script while holding down the power button of the Game & Watch. Try power-cycling the target in between attempts.

If you replaced the SPI flash with a bigger size then also try :

LARGE_FLASH=1 ./5_restore.sh <stlink or jlink or rpi> <mario or zelda>

Getting help and contributing

Feel free to join our discord channel and ask any support questions in #game-and-watch-support.

Other channels:

• #game-and-watch-hacking A channel for general talk about homebrew on the Game & Watch! Please, no ROMs, no flash dumps, etc, but any code related question or other hacking ideas very welcome.
• #replacement-pcb In here we discuss the possibilities and development of replacement PCBs for the Game and Watch.
• game-and-watch-hacking wiki A reference wiki all things hacking the Game & Watch. Including internals.