Firmware Dongle v4

Dongle firmware v4

Released	2026-04
Status	Superseded by v5
Pairs with receiver	v9+
Predecessor	v3
Notable	ACK-payload protocol overhaul — major wire-protocol break.

Downloads

File	Purpose	Download
os4_dongle_v4.bin	App partition.	Download
os4_dongle_v4.bootloader.bin	Chip bootloader.	Download
os4_dongle_v4.partitions.bin	Partition table.	Download
os4_dongle_v4.boot_app0.bin	OTA "next-app" pointer.	Download

Release notes

ACK-payload protocol overhaul.

• Status piggybacks in the auto-ACK (single round trip per command).
• Dynamic payloads enabled (smaller frames take less air time).
• Non-blocking dispatcher (no inner busy-wait, no per-cmd 150 ms stall).
• TDMA-style status polling cycle (round-robin every clockSyncIntervalMs).
• Soft recovery (flush_tx/rx + channel scrub instead of powerDown).
• Payload bounds-checking on receive.
• MAX_RECEIVERS bumped to 32, command queue to 128.
• Packed SHOW_LOADN (up to 6 cues per RF frame).
• Configurable rf_channel and rf_system_id at runtime.

Upgrade notes

• Hard wire-protocol break. Pair with receiver FW v9+; older receivers cannot communicate with this dongle.
• Worth upgrading the entire fleet at once.
• MAX_RECEIVERS=32 makes this the first dongle release that comfortably supports a fleet larger than the original 16-receiver design ceiling.

How to flash

• Flashing a dongle.