FFP is a dead-simple USB to bidirectional SPI bridge for programming iCE40 FPGAs and their SPI flash. The hardware is an STM32F042 and not much else. Firmware and host software is written in Rust.

See software/ for the host-side software, firmware/ for the embedded device firmware, and hardware/ for the hardware design files.

The FFP r1 hardware uses a 5x2 pin 0.05"-pitch connector, which is also commonly used for Cortex family microcontrollers for SWD and JTAG. The pinout is deliberately compatible (though note RESET is moved) to allow hardware reuse and for compatibility with tools such as TagConnect cables. It would also be possible to add SWD support to FFP without changing the hardware, permitting programming of Cortex-M devices.

          ______
    3v3 --|1  2|-- FLASH DI / FPGA DO
    GND --|3  4|-- CLK
    GND --|5  6|-- CS
   NULL --|7  8|-- FPGA nRST
    GND --|9 10|-- FLASH DO / FPGA DI
          ------

This is the same pinout used by amp_flashprog, a custom firmware for Black Magic Probes to bitbang SPI to the same ends.

Software and firmware is licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Hardware design files are licensed under the Creative Commons Attribution license (CC-BY).