User`s manual

10 RabbitCore 2000
As shown in Table 2, pins PA0–PA7 can be used to allow the Rabbit 2000 to be a slave to
another processor. PE0, PE1, PE4, and PE5 can be used as external interrupts INT0A,
INT1A, INT0B, and INT1B. Pins PB0 and PB1 can be used to access the clock on Serial
Port B and Serial Port A of the Rabbit microprocessor. Pins PD4 and PD6 can be pro-
grammed to be optional serial outputs for Serial Ports B and A. PD5 and PD7 can be used
as alternate serial inputs by Serial Ports B and A.
2.2.1 Dedicated Inputs
PB0 and PB1 are designated as inputs because the Rabbit 2000 is operating in an asyn-
chronous mode. Four of the input-only pins are located on PB2–PB5. These pins are used
for the slave port. PB2 and PB3 are slave write and slave read strobes, while PB4 and PB5
serve as slave address lines SA0 and SA1, and are used to access the slave registers (SD0–
SD7), which is the alternate assignment for parallel port A. When Port C is used as a par-
allel port, PC1, PC3, PC5, and PC7 are inputs only. These pins can alternately be selec-
tively enabled to serve as the serial data inputs for Serial Ports D, C, B, and A.
2.2.2 Dedicated Outputs
Two of the output-only pins are located on PB6–PB7. PB7 can also be used with the slave
port as the /SLAVEATTN output. This configuration signifies that the slave is requesting
attention from the master. When Port C is used as a parallel port, PC0, PC2, PC4 and PC6
are outputs only. These pins can alternately serve as the serial data outputs for Serial Ports
D, C, B, and A.