[spf13]

Summary

Fixes LED flickering, wrong/shifted RGB colors (pink/tie-dyed fans), and missed device topology updates on the iBUYPOWER MiniHub (VID_3402&PID_0900, firmware 1.0.1.1).

Root Causes (Proven via Firmware 1.0.1.1 minihub.bin Disassembly & Live Hardware Verification)

1. USB CDC 64-Byte Continuation Buffer Overflow (CDC_Receive_FS at 0x0801AC50..0x0801B1E8):
   • Firmware copies Buf[0..*Len-1] into its 64-byte rx_buf (0x20000258) without clearing rx_buf[*Len..63], and its continuation loop copies all 64 bytes of rx_buf[0..63] into portN_buf regardless of *Len or 150/300-byte buffer bounds.
   • For Channels 1-3 (157 = 64 + 64 + 29 bytes), Packet 3 (*Len = 29) left rx_buf[29..63] populated with Packet 2's LED bytes and overflowed 33 stale bytes (shifted by (95 - 7) % 3 = 1 GRB component -> Pink #C80032 for Blue #0032C8) into port(N+1)_buf[0..32].
   • For Channel 4 (307 = 64*4 + 51 bytes), Packet 5 (*Len = 51) overflowed rx_buf[51..63] (13 bytes) past port4_buf[299] (0x20000643) directly into pwm_buf[0..6] (0x20000644..0x20000650), corrupting the 60-halfword WS2812 0V reset preamble (which build_pwm at 0x0800CC48 never clears after power-on).
   • Fix: MiniHubHub.WritePacketized now sends lighting stream frames in explicit 64-byte zero-padded chunks with high-resolution Stopwatch.GetTimestamp() pacing (5 ms inter-chunk, 25 ms post-latch after Channel 4), and ScrubLightingSramIfSerial zeroes port3_buf, port4_buf, and pwm_buf[0..59] when entering RgbModeSoftware.
2. In-Payload 0xFF Header Collision:
   • Firmware checks rx_buf[0] == 0xFF && rx_buf[1] == 0xEE && rx_buf[2] == 0x03 at packet boundaries; clamping LED channel bytes to 0xFE (MaxLedChannelByte) in MiniHubProtocol.BuildLightingStream prevents LED payload bytes at 64-byte packet boundaries from matching 0xFF command headers.
3. Full 4-Channel Cycle Deduplication & 10 Hz Pacing:
   • Firmware only sets led_update_flag = 1 (0x20000090) on Channel 4 (FF EE 03 04) and re-latches all 4 ports together in main(). MiniHubLightingFrameWriter now stages and writes all 4 channels as an atomic cycle under MiniHubHub.IoLock, deduplicates unchanged static frames (with 1 confirmation cycle), and caps continuous animation streaming at 100 ms (10 Hz).
4. Device Topology Refresh on Connect & Zone Resize:
   • MiniHubHeartbeatWorker now notifies MiniHubLightingDeviceProvider.OnHubStateUpdated() on connect/disconnect (matching Np50HeartbeatWorker), and SetZoneLedCount invokes DevicesChanged so LightingEngine immediately updates its DeviceFrame set.

Verification

• dotnet test (77/77 MiniHub & HubWorker tests passing).
• Live hardware verification on iBUYPOWER MiniHub (COM3, FW 1.0.1.1) across Front 3, Rear, Top, and CPU fans.