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140 Rabbit 3000 Microprocessor
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 9-14 and 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)
adr = 0x038
PF7 PF6 PF5 PF4 PF3 PF2 PF1 PF0
PFFR (W)
adr = 0x03D
pwm[3] pwm[2] pwm[1] pwm[0] x x sclk_c sclk_d
PFDCR (W)
adr = 0x03E
out =
open
drain out =
open
drain out =
open
drain out =
open
drain out =
open
drain out =
open
drain out =
open
drain out =
open
drain
PFDDR (W)
adr = 0x03F dir =
out dir =
out dir =
out dir =
out dir =
out dir =
out dir =
out dir =
out