use dedicated pca counter on efm8bb1 after all

Makefile

@@ -49,9 +49,9 @@
 # sonoff black box
 #TARGET_BOARD = EFM8BB1
 # low cost development board
-TARGET_BOARD = EFM8BB1LCB
+#TARGET_BOARD = EFM8BB1LCB
 # sonoff white box
-#TARGET_BOARD = OB38S003
+TARGET_BOARD = OB38S003
 
 # catches undefined
 ifndef TARGET_BOARD

drivers/efm8bb1/inc/timer_interrupts.h

@@ -14,6 +14,9 @@
 // original portisch used 0xA0 which seems incorrect (they used 0x0B later)
 // and 0x0B value makes more sense:
 // 1/((24500000)/(256-0x0B)) = 0.00001
+// for 1 microsecond
+// hex(256 - (1*10^-6)/(1/(24500000))) = 0xE7.8
+//#define TIMER0_PCA0  0xE8
 #define TIMER0_PCA0  0x0B
 
 // 19200 baud, same on portisch

drivers/efm8bb1/src/hal.c

@@ -33,7 +33,7 @@ void set_clock_mode(void)
 
     // as explained in timer_interrupts.hal
     // 1/((24500000)/(256-0x0B)) = 0.00001 seconds
-    CKCON0 |= T0M__SYSCLK;
+    //CKCON0 |= T0M__SYSCLK;
 
     // FIXME: this is only applicable for split 8-bit timer mode, need to double check
     // FIXME: used for portisch
@@ -206,27 +206,24 @@ void pca0_halt(void)
     CR = 0;
 }
 
-
+// as I recall, we were double clearing this flag
 //void clear_capture_flag(void)
 //{
 //    // overflow flag
 //    //PCA0CN0 &= ~CF__SET;
 //    CF = 0;
 //}
 
-// the time constant is explained in the rcswitch.c file
 
+// time conversion is explained in the rcswitch.c file
 uint16_t countsToTime(const uint16_t counts)
 {
     uint16_t duration;
-
-    //duration = counts / 2;
-
+
     // this only saves two code bytes on ob38s003 apparently
     // equivalent to divide by two
+    //duration = counts / 2;
     duration = counts >> 1;
 
-    //duration = counts;
-
     return duration;
 }

src/main_portisch.c

@@ -541,7 +541,7 @@ void main (void)
     enable_timer0_interrupt();
     enable_timer1_interrupt();
 #elif defined(TARGET_BOARD_EFM8BB1) || defined(TARGET_BOARD_EFM8BB1LCB)
-    // pca used timer0 as timebase on original portisch, we could use the pca counter itself but it is less accurate for microseconds
+    // pca used timer0 as timebase on original portisch, though we could use the pca counter itself
     //init_timer0_8bit_autoreload(TIMER0_PCA0);
     // uart with 19200 baud, uart must use timer1 on efm8bb1
     init_timer1_8bit_autoreload(TIMER1_UART0);