Guides

• Build and load bitstreams (open toolchain): Build with yosys/nextpnr/ecppack (or nextpnr-ice40) and load with openFPGALoader, fujprog, OpenOCD, the ESP32 or DFU.
• Porting iCE40 cores to ECP5: Checklist and primitive map (SB_* to ECP5) for reusing iCE40 cores on the ULX3S.
• USB DFU bootloaders and DFU programming flows: USB DFU bootloaders and flows: the ULX3S/ULX4M US2 bootloader (source, alt settings, flash layout, recovery) and OrangeCrab, Fomu, no2bootloader, pico-ice, BlackIce.

---

Table of contents

• Build and load
• Porting iCE40 to ECP5
• USB DFU