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Add SLT6_Tx subprotocol with NRF24L01 direct transmission support#4

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MRC3742 with Copilot wants to merge 32 commits into
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copilot/copt-slt6-add
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Add SLT6_Tx subprotocol with NRF24L01 direct transmission support#4
MRC3742 with Copilot wants to merge 32 commits into
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copilot/copt-slt6-add

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Copilot AI commented Feb 12, 2026 •
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Adds the SLT6_Tx subprotocol for the Blade Revolution 90 FP helicopter's SLT6 transmitter variant. Decoded from SPI captures of the original Si24R1-based transmitter. The SLT6 protocol uses a triple-address transmission pattern (7B/6B/5B payloads to 3 XOR-derived addresses per 18ms cycle) with discrete flight mode and panic switch encoding.

Key finding: the SLT6 receiver requires native NRF24L01 GFSK modulation — the CC2500 NRF250K emulation layer produces ~20% lower deviation (127kHz vs 160kHz) causing intermittent packet drops at 250kbps.

Protocol implementation (SLT_ccnrf.ino)

  • 8-state callback machine: BUILD_A → A1 → A2 → B1 → B2 → C1 → C2 → BIND
  • Three sub-cycles per triple with TX address byte[0] XOR'd by 0x00/0x06/0x09
  • Hop offsets +0/+3/+6 (mod 15), sequence starts at index 1
  • AETR range limited to 182–842 (10-bit, matching capture data)
  • CH5 flight mode: 3-position discrete (0x30/0x80/0xD0) at ±33% thresholds
  • CH6 panic: binary discrete (0xD0 off, 0x30 active), center=off

NRF24L01 chip selection for SLT (SLT_ccnrf.ino, NRF250K_EMU.ino)

  • SLT passes force_nrf = (option == 0) to XN297_Configure, defaulting to NRF24L01
  • NRF250K_SetTXAddr and NRF250K_WritePayload now check xn297_rf at runtime on dual-chip builds to route to the correct chip
  • All other 250K protocols (BUMBLEB, GD00X, V911S, OMP, etc.) unchanged — still default to CC2500
// SLT-specific: option==0 → NRF24L01 (smooth), option!=0 → CC2500 (with freq tune)
XN297_Configure(XN297_CRCEN, XN297_SCRAMBLED, XN297_250K, option == 0);

Supporting changes

  • Multiprotocol.h: SLT6_Tx = 7 enum value
  • Multi_Protos.ino: subtype string and count updated
  • Multi.txt, _Config.h, Protocols_Details.md: protocol listing and documentation

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Copilot AI and others added 4 commits February 12, 2026 22:16
@MRC3742
Add SLT6_Tx subprotocol for Blade Revolution 90 FP helicopter
bacd2ad 
Decoded from SPI captures of the SLT6 transmitter. The SLT6 protocol
uses triple-address transmission: each 18ms cycle sends to 3 different
TX addresses (byte[0] XOR'd with 0x00/0x06/0x09) with payload sizes
7/6/5 bytes respectively. Flight mode (CH5) and panic (CH6) are
encoded as 8-bit values in bytes 5-6 of the 7-byte payload.

Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
@MRC3742
Address code review: fix doc ordering, add comments for magic numbers
785de25 
Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
@MRC3742
Final: all checks complete
ed5cef0 
Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
@MRC3742
Remove codeql artifact and add to gitignore
98ee07f 
Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
Copilot AI changed the title [WIP] Add SLT6 transmitter support to protocol code Add SLT6_Tx subprotocol for Blade Revolution 90 FP helicopter Feb 12, 2026
Copilot AI requested a review from MRC3742 February 12, 2026 22:18
Copilot AI and others added 2 commits February 13, 2026 00:37
@MRC3742
Fix SLT6_Tx protocol based on 11a/11b capture analysis
b416608 
Key fixes from analyzing the SPI captures:
1. Bind: Single 4B TX-ID bind packet at startup only (no periodic rebind)
2. Hopping: Each sub-cycle uses offset channels (+0/+3/+6 in 15-ch seq),
   hopping_frequency_no advances once per triple (not per sub-cycle)
3. Data: Each sub-cycle rebuilds packet from current channel values
4. Flight mode (CH5): 3-position mapped to 0xD0/0x80/0x30
5. Panic (CH6): Binary switch mapped to 0xD0 (off) / 0x30 (active)
6. Clean separation of SLT6 state machine from other SLT variants

Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
@MRC3742
Address code review: add named constants for address XOR values
0771a1c 
Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
Copilot AI changed the title Add SLT6_Tx subprotocol for Blade Revolution 90 FP helicopter Fix SLT6_Tx subprotocol: correct hopping, bind, and flight mode from capture analysis Feb 13, 2026
@MRC3742
Reduce SLT6_Tx choppiness: merge BUILD+DATA1 phases, add wait_radio, …
2c20512 
…precise timing

- Merge BUILD and DATA1 into a single callback phase (9→6 callbacks/triple)
  to reduce timing jitter from interrupt latency
- Add SLT_wait_radio() before changing radio settings to ensure previous TX
  is complete before channel/address changes
- Use capture-derived timing: 1633us intra-pair (was 1643), 5998us sub-cycle
  (was 6000) matching the original SLT6 transmitter within 0.5us
- Remove dead SLT6 code from SLT_build_packet() (was unreachable)

Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
Copilot AI changed the title Fix SLT6_Tx subprotocol: correct hopping, bind, and flight mode from capture analysis SLT6_Tx: reduce callback jitter causing choppy AETR controls Feb 13, 2026
@MRC3742
Fix SLT6 flight mode: discrete 3-position snap at ±60% thresholds
5314621 
The original SLT6 TX only sends 3 discrete values for flight mode:
0x30 (low), 0x80 (center), 0xD0 (high). The previous code used
convert_channel_8b_limit_deadband() which linearly interpolated,
producing invalid intermediate values (0x52, 0xAE, etc.) that the
receiver likely rejects -- causing both flight mode not switching
until near ±100% and occasional AETR stops/jumps from dropped packets.

Now uses direct Channel_data comparison with ±60% thresholds (±492
from center in raw channel units) to snap to discrete values only.

Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
Copilot AI changed the title SLT6_Tx: reduce callback jitter causing choppy AETR controls Add SLT6_Tx subprotocol for Blade Revolution 90 FP helicopter Feb 13, 2026
Copilot AI changed the title Add SLT6_Tx subprotocol with direct NRF24L01 support and fix NRF250K runtime chip selection Add SLT6_Tx subprotocol and fix NRF250K runtime chip selection for 250K protocols Feb 15, 2026
Copilot AI changed the title Add SLT6_Tx subprotocol and fix NRF250K runtime chip selection for 250K protocols Add SLT6_Tx subprotocol with direct NRF24L01 support and fix NRF250K runtime chip selection Feb 15, 2026
@MRC3742
Revert global 250K chip selection, make SLT force NRF24L01 via force_nrf
6efd525 
Reverts XN297_EMU.ino and NRF250K_EMU.ino to original master code:
- XN297_Configure: 250K always uses CC2500 on dual-chip (original behavior)
- NRF250K_SetTXAddr/WritePayload: compile-time #if/#elif (original behavior)

Makes SLT force NRF24L01 via the existing force_nrf parameter:
- SLT_RF_init: XN297_Configure(..., force_nrf=true) instead of NRF250K_Init()
- SLT uses raw NRF24L01 packets (not XN297 emulation), so it should not be
  affected by the CC2500 default for 250K XN297 protocols
- This applies to ALL SLT variants including SLT6_Tx

Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
Copilot AI changed the title Add SLT6_Tx subprotocol with direct NRF24L01 support and fix NRF250K runtime chip selection Add SLT6_Tx subprotocol with direct NRF24L01 triple-address transmission Feb 17, 2026
@MRC3742
SLT: option==0 selects NRF24L01, option!=0 selects CC2500 with freq t…
6068434 
…uning

Changes force_nrf parameter from hardcoded true to (option == 0).
This is SLT-specific — all other 250K protocols remain unchanged
(always CC2500 on dual-chip modules).

Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
Copilot AI changed the title Add SLT6_Tx subprotocol with direct NRF24L01 triple-address transmission Add SLT6_Tx subprotocol for Blade Revolution 90 FP helicopter Feb 21, 2026
@MRC3742
Fix NRF250K runtime chip selection for dual-chip builds
f99731a 
NRF250K_SetTXAddr and NRF250K_WritePayload now check xn297_rf at
runtime on dual-chip builds, allowing protocols that pass force_nrf
(currently only SLT via option==0) to use the NRF24L01 chip.

On dual-chip builds:
- SetTXAddr: always stores addr for CC2500 path, also writes
  NRF24L01 registers when xn297_rf == XN297_NRF
- WritePayload: NRF24L01 path first with early return when
  xn297_rf == XN297_NRF, CC2500 path otherwise

Single-chip builds unchanged (compile-time selection as before).
Other 250K protocols unchanged (force_nrf defaults to false).

Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
Copilot AI changed the title Add SLT6_Tx subprotocol for Blade Revolution 90 FP helicopter Add SLT6_Tx subprotocol and fix NRF250K runtime chip selection on dual-chip modules Feb 22, 2026
Copilot AI changed the title Add SLT6_Tx subprotocol and fix NRF250K runtime chip selection on dual-chip modules Add SLT6_Tx subprotocol with NRF24L01 direct transmission support Feb 22, 2026
Copilot AI mentioned this pull request Feb 25, 2026
Merged
@MRC3742

MRC3742 commented Feb 25, 2026

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I decided to change the base branch so I've closed this one and opened PR #10 to continue to work on this updated protocol.

@MRC3742 MRC3742 closed this Feb 25, 2026
@MRC3742
MRC3742 deleted the copilot/copt-slt6-add branch April 23, 2026 00:36
Copilot AI mentioned this pull request May 11, 2026
Merged
Copilot AI added a commit that referenced this pull request May 11, 2026
@MRC3742
Add Test #4 analysis section and Section 10 TOC links
29a6a73 
Agent-Logs-Url: https://github.com/MRC3742/DIY-Multiprotocol-TX-Module/sessions/f6804cd8-1c25-4450-bf59-c1e8e7ab5a9e

Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
Copilot AI added a commit that referenced this pull request May 11, 2026
@MRC3742
Refine Test #4 notes for throttle mapping and TOC anchor
7480453 
Agent-Logs-Url: https://github.com/MRC3742/DIY-Multiprotocol-TX-Module/sessions/f6804cd8-1c25-4450-bf59-c1e8e7ab5a9e

Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
Copilot AI added a commit that referenced this pull request May 11, 2026
@MRC3742
Clarify Test #4 throttle mapping heading
e655a26 
Agent-Logs-Url: https://github.com/MRC3742/DIY-Multiprotocol-TX-Module/sessions/f6804cd8-1c25-4450-bf59-c1e8e7ab5a9e

Co-authored-by: MRC3742 <26642502+MRC3742@users.noreply.github.com>
@MRC3742 MRC3742 mentioned this pull request Jul 16, 2026
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