multistomp is a firmware for STM32F1-series microcontrollers that provides USB-MIDI based switches. Typical multistomp builds are based upon footswitches providing a means to control MIDI enabled software such as loopers, guitar amp. simulators and a DAW’s play/record/stop buttons.

Whilst multistomp should be easy to port to most STM32F1-series microcontrollers (and in fact most other STM32 devices with USB device support) it will run most easily on STM32F103x8 devices.

• Install gcc-arm-embedded compiler toolchain (or similar arm-none-eabi- compiler).

• make

• make -C src/bootloader flash

• make -C src/multistomp flash

To flash the bootloader an STLink v2 must be connected to the target boards JTAG/SWD socket.

To flash the main firmware the microcontroller must be connected to the host using its own USB socket.

The firmware can be easily ported by has been tested on an small STM32F103C8T6 based breakout board. Connections required are:

• USB to host computer

• 4x push-to-make switches connected between GND and PA8, PA9, PA10 and PA3.

• 4x LED connected via a 100 ohm current limiting resistor between GND and PA4, PA5, PA6 and PA7.

The LEDs should be mounted such that the LED using PA4 is near to the switch using PA8 (and so on).

multistomp was designed around the following pedal board designed for a Laney amplifier:

The unit has had the wiring loom and original toggle switches removed from it and replaced with push-to-make switches wired up to an ARM Cortex-M3 STM32F103C8T6 STM32 core board development board manufactured by Shenzhen LC Technology (LCTech):