2.3.5.8 Control Registers (CRA, CRB, CRC, CRD)

CRA (0XE):
BIT	Bit Name	Function
0	STARTA	1=START TIMER A, 0=STOP TIMER A. This bit is automatically reset when TIMER A underflow occurs during one-shot mode.
1	PRB6 ON	1=TIMER A output appears on PRB6, O=PRB6 normal port operation.
2	OUT-A MODE	1=TOGGLE output applied on port PRB6, 0=PULSE output applied on port PRB6.
3	RUN-A MODE	1=ONE-SHOT TIMER A operation, 0=CONTINUOUS TIMER A operation.
4	LOADA	1=FORCE LOAD on TIMER A (this is a STROBE input, there is no data storage, bit 4 will always read back a zero and writing a zero has no effect).
5	TMRA INMODE	1=TIMER A counts positive CNTA transitions, 0=TIMER A counts internal C1MHZ pulses.
6	SPA MODE	1=SERIAL A PORT output mode (CNTA sources shift clock), 0=SERIAL A PORT input mode (external shift clock on CNTA)
7	TODA IN	1=50 Hz operation. C7MHZ divided down by 101339 to generate TODA input of 10 Hz. 0=60 Hz operation. C7MHZ divided down by 102273 to generate TODA input of 10 Hz.

CRB (0XF):
BIT	Bit Name	Function
	(Bits 0-4 of the CRB register operate identically to bits 0-4 of the CRA register, except that functions now apply to TIMER B and bit 1 control the output of TIMER B on PRB7).
5,6	TIMERB	Bits 5 and 6 select one of four input modes for TIMER B INMODE as follows: CRB6 CRBS 0 0 TIMER B counts ClMHz pulses. 0 1 TIMER B counts positive CNTA transitions. 1 0 TIMER B counts TIMERA underflow pulses. 1 1 TIMER B counts TIMERA underflows while CNTA is high.
7	ALARM TODA	1=writing to TODA registers sets ALARM, 0=writing to TODA registers sets TODA clock.