Digi Rabbit 5000, User Manual

Page: 99 / 414

Chapter 10 Parallel Port C 99
10.2 Dependencies
10.2.1 I/O Pins
Parallel Port C uses pins PC0 through PC7. These pins can be used individually as data
inputs or outputs; as serial port transmit and receive for Serial ports A–F; as clocks for
Serial Ports C–F; as external I/O strobes; or as outputs for the PWM and Timer C periph-
erals. The input capture peripheral can also watch pins PC7, PC5, PC3, and PC1.
On startup, PC4, PC2, and PC0 are outputs set high, PC6 is set low, and the other pins are
inputs for compatibility with the Rabbit 3000.
The individual pins can be set to be open-drain via PCDCR.
See the associated peripheral chapters for details on how they use Parallel Port C.
10.2.2 Clocks
All outputs on Parallel Port C are clocked by the peripheral clock.
10.2.3 Other Registers
10.2.4 Interrupts
There are no interrupts associated with Parallel Port C.
10.3 Operation
The following steps must be taken before using Parallel Port C.
1. Select the desired input/output direction for each pin via PCDDR.
2. Select driven or open-drain functionality for outputs via PCDCR.
3. If an alternate peripheral output function is desired for a pin, select it via PCALR or
PCAHR and then enable it via PCFR. Refer to the appropriate peripheral chapter for
further use of that pin.
Once the port is set up, data can be read or written by accessing PCDR. The value in
PCDR of an output pin will reflect its current output value, but any value written to an
input pin will not appear on that pin until that pin becomes an output.
Register Function
SACR, SBCR, SCCR,
SDCR, SECR, SFCR Select a Parallel Port C pin as serial data (and
optional clock) input.
ICS1R, ICS2R
Select a Parallel Port C pin as a start/stop condition
for Input Capture input.