DSHOT telemetry optimizations (#8772)

DSHOT telemetry optimizations

src/link/stm32_flash.ld

@@ -53,6 +53,19 @@ SECTIONS
     _etext = .;        /* define a global symbols at end of code */
   } >FLASH
 
+  /* Critical program code goes into CCM RAM */
+  /* Copy specific fast-executing code to CCM RAM */ 
+  ccm_code = LOADADDR(.ccm_code); 
+  .ccm_code :
+  {
+    . = ALIGN(4);
+    ccm_code_start = .; 
+    *(.ccm_code)
+    *(.ccm_code*)
+    . = ALIGN(4);
+    ccm_code_end = .; 
+  } >CCM AT >FLASH
+
 
    .ARM.extab   : { *(.ARM.extab* .gnu.linkonce.armextab.*) } >FLASH
     .ARM : {

src/main/drivers/dma.c

@@ -52,6 +52,7 @@ static dmaChannelDescriptor_t dmaDescriptors[DMA_LAST_HANDLER] = {
 /*
  * DMA IRQ Handlers
  */
+
 DEFINE_DMA_IRQ_HANDLER(1, 1, DMA1_CH1_HANDLER)
 DEFINE_DMA_IRQ_HANDLER(1, 2, DMA1_CH2_HANDLER)
 DEFINE_DMA_IRQ_HANDLER(1, 3, DMA1_CH3_HANDLER)

src/main/drivers/dma.h

@@ -168,7 +168,13 @@ typedef enum {
     .owner.resourceIndex = 0 \
     }
 
-#define DEFINE_DMA_IRQ_HANDLER(d, c, i) void DMA ## d ## _Channel ## c ## _IRQHandler(void) {\
+#if defined(USE_CCM_CODE) && defined(STM32F3)
+#define DMA_HANDLER_CODE CCM_CODE
+#else
+#define DMA_HANDLER_CODE
+#endif
+
+#define DEFINE_DMA_IRQ_HANDLER(d, c, i) DMA_HANDLER_CODE void DMA ## d ## _Channel ## c ## _IRQHandler(void) {\
                                                                         const uint8_t index = DMA_IDENTIFIER_TO_INDEX(i); \
                                                                         dmaCallbackHandlerFuncPtr handler = dmaDescriptors[index].irqHandlerCallback; \
                                                                         if (handler) \

src/main/drivers/pwm_output_dshot.c

@@ -120,7 +120,12 @@ FAST_CODE void pwmDshotSetDirectionOutput(
 
 
 #ifdef USE_DSHOT_TELEMETRY
-FAST_CODE static void pwmDshotSetDirectionInput(
+#if defined(STM32F3)
+CCM_CODE
+#else
+FAST_CODE
+#endif
+static void pwmDshotSetDirectionInput(
     motorDmaOutput_t * const motor
 )
 {
@@ -183,6 +188,11 @@ void pwmCompleteDshotMotorUpdate(void)
     }
 }
 
+#if defined(STM32F3)
+CCM_CODE
+#else
+FAST_CODE
+#endif
 static void motor_DMA_IRQHandler(dmaChannelDescriptor_t *descriptor)
 {
     if (DMA_GET_FLAG_STATUS(descriptor, DMA_IT_TCIF)) {

src/main/drivers/pwm_output_dshot_hal.c

@@ -98,7 +98,7 @@ void pwmDshotSetDirectionOutput(
 }
 
 #ifdef USE_DSHOT_TELEMETRY
-static void pwmDshotSetDirectionInput(
+FAST_CODE static void pwmDshotSetDirectionInput(
     motorDmaOutput_t * const motor
 )
 {
@@ -164,7 +164,7 @@ FAST_CODE void pwmCompleteDshotMotorUpdate(void)
     }
 }
 
-static void motor_DMA_IRQHandler(dmaChannelDescriptor_t* descriptor)
+FAST_CODE static void motor_DMA_IRQHandler(dmaChannelDescriptor_t* descriptor)
 {
     if (DMA_GET_FLAG_STATUS(descriptor, DMA_IT_TCIF)) {
         motorDmaOutput_t * const motor = &dmaMotors[descriptor->userParam];

src/main/drivers/system.c

@@ -253,6 +253,14 @@ void initialiseMemorySections(void)
     memcpy(&tcm_code_start, &tcm_code, (size_t) (&tcm_code_end - &tcm_code_start));
 #endif
 
+#ifdef USE_CCM_CODE
+    /* Load functions into RAM */
+    extern uint8_t ccm_code_start;
+    extern uint8_t ccm_code_end;
+    extern uint8_t ccm_code;
+    memcpy(&ccm_code_start, &ccm_code, (size_t) (&ccm_code_end - &ccm_code_start));
+#endif
+
 #ifdef USE_FAST_RAM
     /* Load FAST_RAM variable intializers into DTCM RAM */
     extern uint8_t _sfastram_data;

src/main/target/common_pre.h

@@ -44,6 +44,7 @@
 #define MINIMAL_CLI
 #define USE_DSHOT
 #define USE_GYRO_DATA_ANALYSE
+#define USE_CCM_CODE
 #endif
 
 #ifdef STM32F4
@@ -135,6 +136,7 @@
 #define DEFAULT_AUX_CHANNEL_COUNT       6
 #endif
 
+
 #ifdef USE_ITCM_RAM
 #define FAST_CODE                   __attribute__((section(".tcm_code")))
 #define FAST_CODE_NOINLINE          NOINLINE
@@ -143,6 +145,12 @@
 #define FAST_CODE_NOINLINE
 #endif // USE_ITCM_RAM
 
+#ifdef USE_CCM_CODE
+#define CCM_CODE              __attribute__((section(".ccm_code")))
+#else
+#define CCM_CODE
+#endif
+
 #ifdef USE_FAST_RAM
 #define FAST_RAM_ZERO_INIT             __attribute__ ((section(".fastram_bss"), aligned(4)))
 #define FAST_RAM                    __attribute__ ((section(".fastram_data"), aligned(4)))