Jameco Electronics 2000 13.Parallel Port F Registers, 14.Parallel Port F Register Functions

9.6 Parallel Port F

Parallel Port F is a byte-wide port with each bit programmable for data direction and drive. These are simple inputs and outputs controlled and reported in the Port F Data Register. As outputs, the bits of the port are buffered, with the data written to the Port F Data Regis- ter transferred to the output pins on a selected timing edge. The outputs of Timer A1, Timer B1, or Timer B2 can be used for this function, with each nibble of the port having a separate select field to control this timing.

These inputs and outputs are also used for access to other peripherals on the chip. As out- puts, the Parallel Port F outputs can carry the four Pulse-Width Modulator outputs. As inputs, Parallel Port F inputs can carry the inputs to the quadrature decoders. When Serial Port C or Serial Port D is used in the clocked serial mode, two pins of Parallel Port F are used to carry the serial clock signals. When the internal clock is selected in these serial ports, the corresponding bit of Parallel Port F is set as an output.

The Parallel Port F registers and their functions are described in Table 9-14and in Table 9-15.

Table 9-13. Parallel Port F Registers

Register Name	Mnemonic	I/O address	R/W	Reset
Port F Data Register	PFDR	0x38	R/W	xxxxxxxx
Port F Control Register	PFCR	0x3C	W	xx00xx00
Port F Function Register	PFFR	0x3D	W	xxxxxxxx
Port F Drive Control Register	PFDCR	0x3E	W	xxxxxxxx
Port F Data Direction Register	PFDDR	0x3F	W	00000000

Table 9-14. Parallel Port F Register Functions

	Bit 7	Bit 6	Bit 5	Bit 4	Bit 3	Bit 2	Bit 1	Bit 0
PFDR (R/W)	PF7	PF6	PF5	PF4	PF3	PF2	PF1	PF0
adr = 0x038
PFFR (W)	pwm[3]	pwm[2]	pwm[1]	pwm[0]	x	x	sclk_c	sclk_d
adr = 0x03D
PFDCR (W)	out =	out =	out =	out =	out =	out =	out =	out =
	open	open	open	open	open	open	open	open
adr = 0x03E
	drain	drain	drain	drain	drain	drain	drain	drain
PFDDR (W)	dir =	dir =	dir =	dir =	dir =	dir =	dir =	dir =
adr = 0x03F	out	out	out	out	out	out	out	out

140 Rabbit 3000 Microprocessor