fixed decoding count to time conversion constant on efm8bb1

drivers/efm8bb1/src/hal.c

@@ -223,8 +223,9 @@ void load_timer1(const uint16_t value)
 void pca0_init(void)
 {
 	// default pca acts normally when controller is idle
+	// default source is system clock divided by 12
 	// default pca CF overflow is disabled
-	PCA0MD |= CPS__SYSCLK_DIV_12;
+	//PCA0MD &= ~CPS__SYSCLK_DIV_12;
 
 	// enable both positive and negative edge triggers
 	PCA0CPM0 |= CAPP__ENABLED;
@@ -233,12 +234,12 @@ void pca0_init(void)
 
 void pca0_run(void)
 {
-    PCA0CN0 |= CR__RUN;
+    CR = true;
 }
 
 void pca0_halt(void)
 {
-    PCA0CN0 &= ~CR__RUN;
+    CR = false;
 }
 
 
@@ -263,11 +264,13 @@ void clear_capture_flag(void)
 	CCF0 = 0;
 }
 
-// FIXME: explain counts to time conversion constant
+// the time constant is explained in the rcswitch.c file
+
 unsigned long countsToTime(const unsigned long duration)
 {
     unsigned long converted;
-    converted = duration * 2;
+
+    converted = duration / 2;
 
     return converted;
 }

drivers/ob38s003/inc/hal.h

@@ -234,7 +234,7 @@ extern void disable_serial_interrupt(void);
 extern bool global_interrupts_are_enabled(void);
 
 void load_timer0(const uint16_t load);
-extern uint16_t get_timer2(void);
+extern uint16_t get_capture_mode(void);
 
 extern void clear_capture_flag(void);
 

drivers/ob38s003/src/hal.c

@@ -195,9 +195,9 @@ void init_timer2_as_capture(void)
     //(i.e., P1.6 or RDATA which is input from D0 of radio)
     CCEN  = 0x60;
 
-    // timer 2 input frequency from prescaler
+    // timer 2 input frequency from prescaler (i.e., TSPS set to 1/24 below)
     // timer 2 mode 0 auto reload (generated by a timer 2 overflow)
-    // timer 2 is clocked with 1/4 (0x51) or 1/24 (0xD1) of the oscillator frequency (prescaler select bit)
+    // timer 2 is clocked with 1/24 of the oscillator frequency (prescaler select bit)
     // (e.g., 0.25 microseconds per count)
     T2CON = 0xD1;
 }
@@ -208,7 +208,7 @@ bool global_interrupts_are_enabled(void)
 }
 
 
-uint16_t get_timer2(void)
+uint16_t get_capture_mode(void)
 {
     return (CCH1 << 8) | CCL1;
 }
@@ -223,10 +223,11 @@ unsigned char get_stack_pointer(void)
     return SP;
 }
 
-// FIXME: on counts to time conversion
+// the time constant is explained in the rcswitch.c file
 unsigned long countsToTime(const unsigned long duration)
 {
     unsigned long converted;
+
     converted = (duration * 3) / 2;
 
     return converted;

drivers/ob38s003/src/timer_interrupts.c

@@ -151,7 +151,7 @@ void timer1_isr(void) __interrupt (d_T1_Vector)
 //-----------------------------------------------------------------------------
 void timer2_isr(void) __interrupt (d_T2_Vector)
 {
-    uint16_t currentCapture = get_timer2();
+    uint16_t currentCapture = get_capture_mode();
 
     capture_handler(currentCapture);
 

src/rcswitch.c

@@ -190,22 +190,22 @@ void capture_handler(const uint16_t currentCapture)
         // FIXME: no magic numbers
         // FIXME: seems like a bad idea to make wrap around calculation depend on variable type, what if it changes
         // if overflow, we must compute difference by taking into account wrap around at maximum variable size
-        duration = ULONG_MAX  - previous + current;
+        duration = UINT_MAX  - previous + current;
     } else {
         duration = current - previous;
     }
 
-    // FIXME: no magic numbers
     // e.g., EFM8BB1
 	// e.g. (1/(24500000))*(49/2) = 1      microsec
 	// e.g. (1/(24500000/12))*2   = 0.9796 microsec
+	// so need to do the inverse to go from counts to time (i.e., counts * 1/2 = time)
 	// (1/(24500000/12))*dec(0xFFFF) = 32.0987755 millisecs max
 
     // e.g., OBS38S003
     // e.g. prescale at (1/4) at 16 MHz, four counts are needed to get one microsecond
-    // e.g. prescale at (1/24) at 16 MHz
+    // e.g. prescale at (1/24) at 16 MHz, 2/3 counts are need to get one microsecond
+    // so inverse is counts * 3/2 = time
     // e.g., (1/(16000000/24)) * dec(0xFFFF) = 98.30 milliseconds maximum can be counted
-    // FIXME: show why 3/2 conversion works
     duration = countsToTime(duration);
 
     // from oscillscope readings it appears that first sync pulse of first radio packet is frequently not output properly by receiver