Using CTRA and CTRB

In Spin, CTRx can be read/written just like any other register or pre-defined variable. As soon as this register is written, the new operating mode goes into effect for the counter. For example:

CTRA := %00100 << 26

The above code sets CTRA's CTRMODE field to the NCO mode (%00100) and all other bits to zero.

Counter Modes (CTRMODE Field Values)

CTRMODE	Description	Accumulate FRQx to PHSx	APIN Output*	BPIN Output*
%00000	Counter disabled (off)	0 (never)	0 (none)	0 (none)
%00001 %00010 %00011	PLL internal (video mode) PLL single-ended PLL differential	1 (always) 1 1	0 PLLx PLLx	0 0 !PLLx
%00100 %00101	NCO single-ended NCO differential	1 1	PHSx[31] PHSx[31]	0 !PHSx[31]
%00110 %00111	DUTY single-ended DUTY differential	1 1	PHSx-Carry PHSx-Carry	0 !PHSx-Carry
%01000 %01001 %01010 %01011	POS detector POS detector with feedback POSEDGE detector POSEDGE detector w/ feedback	A1 A1 A1 & !A2 A1 & !A2	0 0 0 0	0 !A1 0 !A1
%01100 %01101 %01110 %01111	NEG detector NEG detector with feedback NEGEDGE detector NEGEDGE detector w/ feedback	!A1 !A1 !A1 & A2 !A1 & A2	0 0 0 0	0 !A1 0 !A1
%10000 %10001 %10010 %10011 %10100 %10101 %10110 %10111 %11000 %11001 %11010 %11011 %11100 %11101 %11110 %11111	LOGIC never LOGIC !A & !B LOGIC A & !B LOGIC !B LOGIC !A & B LOGIC !A LOGIC A <> B LOGIC !A \| !B LOGIC A & B LOGIC A == B LOGIC A LOGIC A \| !B LOGIC B LOGIC !A \| B LOGIC A \| B LOGIC always	0 !A¹& !B¹ A1 & !B1 !B1 !A1 & B1 !A1 A1 <> B1 !A1 \| !B1 A1 & B1 A1 == B1 A1 A1 \| !B1 B1 !A1 \| B1 A1 \| B1 1	0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0	0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

*Must set corresponding DIR bit to affect pin
A1 = APIN input delayed by 1 clock
A2 = APIN input delayed by 2 clocks
B1 = BPIN input delayed by 1 clock|