Merge pull request #4607 from iNavFlight/de_dshot_fix

Align INAV's DSHOT timer divisor rounding with Betaflight's way

Makefile

@@ -119,7 +119,7 @@ $(error Unknown target MCU specified.)
 endif
 
 GROUP_1_TARGETS := ALIENFLIGHTF3 ALIENFLIGHTF4 AIRHEROF3 AIRHEROF3_QUAD COLIBRI_RACE LUX_RACE SPARKY REVO SPARKY2 COLIBRI KISSFC FALCORE FF_F35_LIGHTNING FF_FORTINIF4 FF_PIKOF4 FF_PIKOF4OSD
-GROUP_2_TARGETS := SPRACINGF3 SPRACINGF3EVO SPRACINGF3EVO_1SS SPRACINGF3MINI SPRACINGF4EVO CLRACINGF4AIR CLRACINGF4AIRV2 BEEROTORF4 BETAFLIGHTF3 BETAFLIGHTF4 PIKOBLX SPRACINGF3NEO
+GROUP_2_TARGETS := SPRACINGF3 SPRACINGF3EVO SPRACINGF3EVO_1SS SPRACINGF3MINI SPRACINGF4EVO CLRACINGF4AIR CLRACINGF4AIRV2 BEEROTORF4 BETAFLIGHTF3 BETAFLIGHTF4 PIKOBLX
 GROUP_3_TARGETS := OMNIBUS AIRBOTF4 BLUEJAYF4 OMNIBUSF4 OMNIBUSF4PRO OMNIBUSF4V3 FIREWORKSV2 SPARKY2 MATEKF405 OMNIBUSF7 DYSF4PRO OMNIBUSF4PRO_LEDSTRIPM5 OMNIBUSF7NXT OMNIBUSF7V2 ASGARD32F4
 GROUP_4_TARGETS := ANYFC ANYFCF7 ANYFCF7_EXTERNAL_BARO ANYFCM7 ALIENFLIGHTNGF7 PIXRACER YUPIF4 YUPIF4MINI YUPIF4R2 YUPIF7 MATEKF405SE MATEKF411 MATEKF722 MATEKF405OSD MATEKF405_SERVOS6 NOX
 GROUP_5_TARGETS := ASGARD32F7 CHEBUZZF3 CLRACINGF4AIRV3 DALRCF405 DALRCF722DUAL DYSF4PROV2 F4BY FISHDRONEF4 FOXEERF405 FOXEERF722DUAL FRSKYF3 FRSKYF4 FURYF3 FURYF3_SPIFLASH FURYF4OSD

src/main/drivers/pwm_output.c

@@ -50,7 +50,7 @@
 
 #define DSHOT_MOTOR_BIT_0       7
 #define DSHOT_MOTOR_BIT_1       14
-#define DSHOT_MOTOR_BITLENGTH   19
+#define DSHOT_MOTOR_BITLENGTH   20
 
 #define DSHOT_DMA_BUFFER_SIZE   18 /* resolution + frame reset (2us) */
 #endif

src/main/drivers/timer_impl_hal.c

@@ -18,6 +18,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include <string.h>
+#include <math.h>
 
 #include "platform.h"
 
@@ -82,7 +83,7 @@ void impl_timerConfigBase(TCH_t * tch, uint16_t period, uint32_t hz)
     }
 
     timHandle->Instance = timer;
-    timHandle->Init.Prescaler = (timerGetBaseClock(tch) / hz) - 1;
+    timHandle->Init.Prescaler = lrintf((float)timerGetBaseClock(tch) / hz + 0.01f) - 1;
     timHandle->Init.Period = (period - 1) & 0xffff; // AKA TIMx_ARR
     timHandle->Init.RepetitionCounter = 0;
     timHandle->Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

src/main/drivers/timer_impl_stdperiph.c

@@ -17,6 +17,7 @@
 
 #include <stdbool.h>
 #include <stdint.h>
+#include <math.h>
 
 #include "platform.h"
 
@@ -67,7 +68,7 @@ void impl_timerConfigBase(TCH_t * tch, uint16_t period, uint32_t hz)
 
     TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
     TIM_TimeBaseStructure.TIM_Period = (period - 1) & 0xffff; // AKA TIMx_ARR
-    TIM_TimeBaseStructure.TIM_Prescaler = (timerGetBaseClock(tch) / hz) - 1;
+    TIM_TimeBaseStructure.TIM_Prescaler = lrintf((float)timerGetBaseClock(tch) / hz + 0.01f) - 1;
     TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
     TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
     TIM_TimeBaseInit(tim, &TIM_TimeBaseStructure);