Glue (hot glue, mounting tape) the LiPo battery to the perfboard bottom layer.

If the battery has a molex connector, no wiring/solderin is required.

1. Print the keyboard overlay on heavy weight white paper
2. Cut out the overlay
3. Laminate the overlay
4. Cut out the laminated overlay
5. Cut holes for the push buttons, I use a leather puncher (4 mm holes

Flash the 4TH Calculator binary MecrispCubeCalcFS.bin to the WB55 Nucleo dongle. Using the built-in USB DFU bootloader.

The USB Dongle does not have a ST-Link interface, but the STM32WB has a built-in boot-loader. This bootloader works via USB. As programming tool I use the the STM32CubeProgrammer package.

1. For programming the switch SW2 has to be in position BOOT0.
2. Connect the dongle USB with the computer.
3. Flash the firmware with STM32CubeProgrammer, either with the CLI (see below) or the GUI (open file .., Download)
4. Disconnect dongle from the computer.
5. Set the switch SW2 to position 0.

$ alias cubepgmcli='/opt/STMicroelectronics/STM32Cube/STM32CubeProgrammer/bin/STM32_Programmer_CLI'
$ cubepgmcli -c port=USB1 -d MecrispCubeCalcFS.bin 0x8000000 

You can find the BLE Stack and FUS in STM32CubeWB or from GitHub, in the directory Projects/STM32WB_Copro_Wireless_Binaries. At time of writing the FUS is Version 1.2.0, the stack v1.19.1. The STM32CubeProgrammer is v2.16.0.

1. For programming the switch SW2 has to be in position BOOT0.
2. Connect the dongle USB with the computer.
3. Flash the firmware with STM32CubeProgrammer, either with the CLI (see below) or the GUI (use the firmware upgrade service, start address usually 0x080CE000)
4. Disconnect dongle from the computer.
5. Set the switch SW2 to position 0.

$ alias cubepgmcli='/opt/STMicroelectronics/STM32Cube/STM32CubeProgrammer/bin/STM32_Programmer_CLI'
$ cd STM32Cube_FW_WB_V1.19.1/Projects/STM32WB_Copro_Wireless_Binaries/STM32WB5x
$ cubepgmcli -c port=USB1 -fwupgrade stm32wb5x_BLE_Stack_full_fw.bin 0x080CE000 firstinstall=0