HAL_ChibiOS: ensure RCIN sigbuf has even number of words

ObjectBuffer rounds up by 1, leaving an odd number of words, which
caused DSM RC input corruption

libraries/AP_HAL_ChibiOS/RCInput.cpp

@@ -124,8 +124,8 @@ void RCInput::_timer_tick(void)
 #if HAL_USE_ICU == TRUE
     const uint32_t *p;
     uint32_t n;
-    while ((p = sig_reader.sigbuf.readptr(n)) != nullptr) {
-        rcin_prot.process_pulse_list(p, n, sig_reader.need_swap);
+    while ((p = (const uint32_t *)sig_reader.sigbuf.readptr(n)) != nullptr) {
+        rcin_prot.process_pulse_list(p, n*2, sig_reader.need_swap);
         sig_reader.sigbuf.advance(n);
     }
 #endif

libraries/AP_HAL_ChibiOS/SoftSigReader.cpp

@@ -102,29 +102,10 @@ void SoftSigReader::_irq_handler(void* self, uint32_t flags)
     dmaStreamSetTransactionSize(sig_reader->dma, SOFTSIG_BOUNCE_BUF_SIZE);
     dmaStreamSetMode(sig_reader->dma, sig_reader->dmamode);
     dmaStreamEnable(sig_reader->dma);
-    sig_reader->sigbuf.push(sig_reader->signal2, SOFTSIG_BOUNCE_BUF_SIZE);
+    sig_reader->sigbuf.push((const pulse_t *)sig_reader->signal2, SOFTSIG_BOUNCE_BUF_SIZE/2);
 }
 
 
-bool SoftSigReader::read(uint32_t &widths0, uint32_t &widths1)
-{
-    if (sigbuf.pop(widths0) && sigbuf.pop(widths1)) {
-        //the data is period and width, order depending on which
-        //channel is used and width type (0 or 1) depends on mode
-        //being set to HIGH or LOW. We need to swap the words when on
-        //channel 1
-        if (need_swap) {
-            uint32_t tmp = widths1;
-            widths1 = widths0;
-            widths0 = tmp;
-        }
-        widths1 -= widths0;
-    } else {
-        return false;
-    }
-    return true;
-}
-
 #endif // HAL_USE_ICU
 
 #endif //CONFIG_HAL_BOARD == HAL_BOARD_CHIBIOS

libraries/AP_HAL_ChibiOS/SoftSigReader.h

@@ -25,7 +25,7 @@
 #define INPUT_CAPTURE_FREQUENCY 1000000 //capture unit in microseconds
 
 #ifndef SOFTSIG_MAX_SIGNAL_TRANSITIONS
-#define SOFTSIG_MAX_SIGNAL_TRANSITIONS 256
+#define SOFTSIG_MAX_SIGNAL_TRANSITIONS 128
 #endif
 
 // we use a small bounce buffer size to minimise time in the DMA
@@ -36,7 +36,6 @@ class ChibiOS::SoftSigReader {
     friend class ChibiOS::RCInput;
 public:
     bool attach_capture_timer(ICUDriver* icu_drv, icuchannel_t chan, uint8_t dma_stream, uint32_t dma_channel);
-    bool read(uint32_t &widths0, uint32_t &widths1);
 
 private:
     uint32_t *signal;
@@ -49,7 +48,11 @@ private:
     uint32_t dmamode;
     ICUConfig icucfg;
     ICUDriver* _icu_drv = nullptr;
-    ObjectBuffer<uint32_t> sigbuf{SOFTSIG_MAX_SIGNAL_TRANSITIONS};
+    typedef struct PACKED {
+        uint32_t w0;
+        uint32_t w1;
+    } pulse_t;
+    ObjectBuffer<pulse_t> sigbuf{SOFTSIG_MAX_SIGNAL_TRANSITIONS};
     bool need_swap;
 };
 

libraries/AP_HAL_ChibiOS/SoftSigReaderInt.cpp

@@ -93,20 +93,20 @@ void SoftSigReaderInt::init(EICUDriver* icu_drv, eicuchannel_t chan)
 void SoftSigReaderInt::_irq_handler(EICUDriver *eicup, eicuchannel_t aux_channel)
 {
     eicuchannel_t channel = get_pair_channel(aux_channel);
-    uint16_t value1 = eicup->tim->CCR[channel];
-    uint16_t value2 = eicup->tim->CCR[aux_channel];
+    pulse_t pulse;
+    pulse.w0 = eicup->tim->CCR[channel];
+    pulse.w1 = eicup->tim->CCR[aux_channel];
     
-    _instance->sigbuf.push(value1);
-    _instance->sigbuf.push(value2);
+    _instance->sigbuf.push(pulse);
 
     //check for missed interrupt 
     uint32_t mask = (STM32_TIM_SR_CC1OF << channel) | (STM32_TIM_SR_CC1OF << aux_channel);
     if ((eicup->tim->SR & mask) != 0) {
         //we have missed some pulses
         //try to reset RCProtocol parser by returning invalid value (i.e. 0 width pulse)
-        _instance->sigbuf.push(value2);
-        //second 0 width pulse to keep polarity right
-        _instance->sigbuf.push(value2);
+        pulse.w0 = 0;
+        pulse.w1 = 0;
+        _instance->sigbuf.push(pulse);
         //reset overcapture mask
         eicup->tim->SR &= ~mask;
     }
@@ -114,12 +114,12 @@ void SoftSigReaderInt::_irq_handler(EICUDriver *eicup, eicuchannel_t aux_channel
 
 bool SoftSigReaderInt::read(uint32_t &widths0, uint32_t &widths1)
 {
-    uint16_t p0, p1;
     if (sigbuf.available() >= 2) {
-        if (sigbuf.pop(p0) && sigbuf.pop(p1)) {
-            widths0 = uint16_t(p0 - last_value);
-            widths1 = uint16_t(p1 - p0);
-            last_value = p1;
+        pulse_t pulse;
+        if (sigbuf.pop(pulse)) {
+            widths0 = uint16_t(pulse.w0 - last_value);
+            widths1 = uint16_t(pulse.w1 - pulse.w0);
+            last_value = pulse.w1;
             return true;
         }
     }

libraries/AP_HAL_ChibiOS/SoftSigReaderInt.h

@@ -23,7 +23,7 @@
 
 #define INPUT_CAPTURE_FREQUENCY 1000000 //capture unit in microseconds
 #ifndef SOFTSIG_MAX_SIGNAL_TRANSITIONS
-#define SOFTSIG_MAX_SIGNAL_TRANSITIONS 256
+#define SOFTSIG_MAX_SIGNAL_TRANSITIONS 128
 #endif
 
 
@@ -49,8 +49,11 @@ private:
     static void _irq_handler(EICUDriver *eicup, eicuchannel_t channel);
     
     static eicuchannel_t get_pair_channel(eicuchannel_t channel);
-
-    ObjectBuffer<uint16_t> sigbuf{SOFTSIG_MAX_SIGNAL_TRANSITIONS};
+    typedef struct PACKED {
+        uint16_t w0;
+        uint16_t w1;
+    } pulse_t;
+    ObjectBuffer<pulse_t> sigbuf{SOFTSIG_MAX_SIGNAL_TRANSITIONS};
     EICUConfig icucfg;
     EICUChannelConfig channel_config;
     EICUChannelConfig aux_channel_config;

libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat

@@ -133,7 +133,7 @@ define NO_DATAFLASH TRUE
 define DMA_RESERVE_SIZE 0
 
 # reduce memory usage in RCInput
-define SOFTSIG_MAX_SIGNAL_TRANSITIONS 256
+define SOFTSIG_MAX_SIGNAL_TRANSITIONS 128
 
 define IOMCU_FW TRUE
 define NO_FASTBOOT