Firmware Receiver v9

Receiver firmware v9

Released	2026-04
Status	Superseded by v10
Pairs with dongle	v4+
Predecessor	v8
Notable	ACK-payload protocol overhaul — major wire-protocol break.

Downloads

File	Purpose	Download
os4_receiver_v9.bin	App partition.	Download
os4_receiver_v9.bootloader.bin	Chip bootloader.	Download
os4_receiver_v9.partitions.bin	Partition table.	Download
os4_receiver_v9.boot_app0.bin	OTA "next-app" pointer.	Download

Release notes

ACK-payload protocol overhaul (matches dongle FW v4):

• Status piggybacks in the auto-ACK FIFO (no separate sendStatus TX path).
• Dynamic payloads enabled.
• Payload bounds-checked on receive.
• ADDITIONAL_CLOCK_TX_OFFSET now applied to clock_offset.
• Hot-path Serial prints gated behind DEBUG_PRINT.
• Show-time LED animations are now non-blocking state machines so radio servicing isn't stalled during them.
• Configurable rf_channel and rf_system_id (compile-time, matches dongle).
• SHOW_LOADN handler (packed multi-cue load).

Upgrade notes

• Hard wire-protocol break. Pair with dongle FW v4+; older dongles speak the pre-ACK-payload protocol and cannot communicate with v9 receivers.
• Worth upgrading the entire fleet at once.

How to flash

• Wired only. Flashing a receiver.