iceflashprog

A simple USB flash programmer for iCE40-based FPGA development boards.

Description

This is a simple and kinda generic flash memory programmer designed for Olimex's line of Lattice iCE40 FPGA evaluation boards, due to their standard UEXT programming headers, but potentially adaptable to any other evaluation boards that use the same FPGAs or flash memories.

The device implements a USB HID interface, which means that it is automatically recognized by any operating system without installing drivers. The iceflashprog binary should be used to interact with the device.

The serial port interface available on the UEXT header is not implemented (yet?)

This project includes the firmware and the host software required to interact with the USB device.

Hardware

The hardware is based on my STM32F0 development board, with a flat cable soldered directly to the board, instead of using header pins. The firmware fits the smallest microcontroller supported by the devboard, so any board should work fine for this project.

The solder jumper connected to Pin 1 of the UEXT header, which is open by default, should NOT be closed because the STM32F0 development board is powered by the USB port.

The development board is straightforward to build, containing mostly PTH parts. The Gerber files are available and can be uploaded to your favorite PCB fabrication house.

Users not willing to build the UEXT cable can instead install header pins on the development board, then connect them with DuPont cables.

LED pattern

When the device is powered on (or reset, either by the USB host or by the internal watchdog), the LED will stay ON until it is successfully enumerated by the USB host. After that, it will be ON as long as there is data being transferred to the flash memory via SPI (very fast blinking).

3D case

A very simple 3D case model is provided. It should be easy to print, and is compatible with M2 self-tapping screws.

Firmware

This project includes firmware for the STM32F042 microcontroller available on the development boards. A prebuilt binary is available from the release files. It is compatible with all microcontrollers supported by the STM32F0 development boards.

The easiest way to flash the binary to the microcontroller is via USB, by using the default DFU bootloader. This requires the installation of the dfu-util binary to the system.

To start the microcontroller in bootloader mode, please connect together the pins marked as "BOOTLOADER" in the devboard, either by using a jumper or a DuPont cable, and then connect the USB cable. If everything is OK, the LED will turn on.

Run the following command to check if dfu-util can access the device:

$ dfu-util -l

The last lines should look similar to:

Found DFU: [0483:df11] ver=2200, devnum=1, cfg=1, intf=0, path="8-4.4.1", alt=0, name="@Internal Flash  /0x08000000/032*0001Kg", serial="FFFFFFFEFFFF"
Found DFU: [0483:df11] ver=2200, devnum=1, cfg=1, intf=0, path="8-4.4.1", alt=1, name="@Option Bytes  /0x1FFFF800/01*016 e", serial="FFFFFFFEFFFF"

After extracting the .zip file containing the DFU firmware, from a shell inside the extracted directory, run:

$ dfu-util -D iceflashprog.dfu

If the command reports success, just reset the device, by removing and connecting the USB port, and it should be working!

Host software

This project includes a program to allow writing and reading the flash memory contained in the FPGA development board from a computer. A prebuilt binary is available from the release files, for Linux (amd64 and arm64), MacOS (arm64) and Windows (amd64). Other architectures are supported, but users would need to rebuild the application from source. It is written in pure Go, so a Go compiler >= 1.24.0 is required for that.

Linux users may need to install a udev .rules file that is included with the prebuilt binary. MacOS users may need to cleanup quarantine xattrs from the binary before running because it is not signed. As these are operating system quirks not specific to this software, solve it is out of scope of this documentation.

To check if everything is connected and powered correctly, type:

$ iceflashprog -d

It should output something similar to:

Manufacturer: 0x1c
Device ID: 0x7015

To write a bitstream binary to flash, after erasing it and verifying afterwards, type:

$ iceflashprog bitstream.bin

To read flash memory to a file, type:

$ iceflashprog -r bitstream.bin

For more details on the program options, type:

$ iceflashprog -h

License

The software is released under a GNU General Public License v2.0 only license.