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Fix Special/Flood jam duty cycle: 26% → 85%

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Root cause: transmit() wraps startTransmit()+finishTransmit(). RadioLib's
finishTransmit() has a timeout of (1/bitRate)*128 = 0.512ms at 250kbps,
which truncates to 0ms, causing immediate RADIOLIB_ERR_TX_TIMEOUT. The
CC1101 was transmitting its 2.59ms packet correctly, but the 10ms inter-
packet guard meant 7.41ms of dead air — only 26% duty cycle. A rolling-
code fob sends 3 attempts in 200ms; with 26% jamming there is a 40%
chance all 3 get through.

Fix: switch to startTransmit() (non-blocking) and reduce guard to 3ms
(JAM_SPECIAL_DELAY_MS / JAM_FLOOD_DELAY_MS). CC1101 finishes the 2.59ms
packet autonomously and returns to IDLE. startTransmit() restarts cleanly
every ~3ms without ever cutting a packet short. Duty cycle: ~85%.

Made-with: Cursor
This commit is contained in:
drjones
2026-04-02 18:39:50 -07:00
parent a44462e905
commit a867707a12
2 changed files with 34 additions and 20 deletions
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6
include/config.h
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@@ -64,7 +64,11 @@
#define JAM_FLOOD_DEV_R1_KHZ 140.0f
#define JAM_FLOOD_DEV_R2_KHZ 200.0f
// Special jam: 60-byte random payloads with 10ms delay (cypher-pulse exact clone).
// Special/Flood jam timing: CC1101 at 250 kbps takes 2.59ms to send a 61-byte packet (preamble+sync+data).
// 3ms restart gap allows each packet to complete naturally before startTransmit() is called again.
// Duty cycle: ~85%. 10ms (original cypher-pulse) only achieves 26% — too many gaps for rolling-code fobs.
#define JAM_SPECIAL_DELAY_MS 3
#define JAM_FLOOD_DELAY_MS 3
// SmartRF-style dump: config space only (TI SWRS061); PATABLE/ strobes not included.
#define CC1101_CFG_REG_LAST 0x2E