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A Raspberry Pi HAT for connecting retro joysticks and buttons.

Programming the flash

First check that WP jumper on the back is NOT bridged and execute the following commands to enable EEPROM flashing:

sudo bash -c 'echo "dtparam=i2c_vc=on" >> /boot/config.txt'
sudo reboot

After system has rebooted, install and compile tools:

git clone
cd hats/eepromutils/
make clean ; make

clean the EEPROM:

dd if=/dev/zero ibs=1k count=4 of=blank.eep
sudo ./ -w -f=blank.eep -t=24c32

create EEPROM file:

dtc -@ -b 0 -I dts -O dtb -o retrohat.dtbo retrohat.dts
./eepmake retrohat.txt retrohat.eep retrohat.dtbo

and flash the EEPROM:

sudo ./ -w -f=retrohat.eep -t=24c32
sudo reboot

Now you can solder-bridge WP jumper on your board and disable EEPROM I2C:

sudo bash -c 'sed -i "/^dtparam=i2c_vc=on$/d" /boot/config.txt'
sudo reboot

To verify operation succeeded, use raspi-gpio (expected INPUT for all pins):

sudo raspi-gpio get
sudo cat /sys/kernel/debug/gpio

After reboot, keys will be automatically detected. To verify workings you can use evtest: