From f0bdc93a25f1c9d154c4ec95f91f19339ce63f61 Mon Sep 17 00:00:00 2001
From: blckmn <blackman@xtra.com.au>
Date: Sat, 15 Jul 2017 14:51:59 +1000
Subject: [PATCH] Fix motor twitch when unarmed and using synced protocols.

---
 src/main/drivers/pwm_output.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/main/drivers/pwm_output.c b/src/main/drivers/pwm_output.c
index 9c05608fb7..01c0eb8e9f 100644
--- a/src/main/drivers/pwm_output.c
+++ b/src/main/drivers/pwm_output.c
@@ -311,13 +311,14 @@ void motorDevInit(const motorDevConfig_t *motorConfig, uint16_t idlePulse, uint8
 #endif
 
         /* standard PWM outputs */
-        const unsigned pwmRateHz = useUnsyncedPwm ? motorConfig->motorPwmRate : ceilf(1 / (sMin + sLen * 2));
+        // margin of safety is 4 periods when unsynced
+        const unsigned pwmRateHz = useUnsyncedPwm ? motorConfig->motorPwmRate : ceilf(1 / ((sMin + sLen) * 4));
 
         const uint32_t clock = timerClock(timerHardware->tim);
         /* used to find the desired timer frequency for max resolution */
         const unsigned prescaler = ((clock / pwmRateHz) + 0xffff) / 0x10000; /* rounding up */
         const uint32_t hz = clock / prescaler;
-        const unsigned period = hz / pwmRateHz;
+        const unsigned period = useUnsyncedPwm ? hz / pwmRateHz : 0xffff;
 
         /* 
             if brushed then it is the entire length of the period.