![](http://datasheet.mmic.net.cn/Rabbit-Semiconductor/668-0003-C_datasheet_95667/668-0003-C_61.png)
55
I/O Port D
PD0–PD7
Input/
Output/
output open
drain
I/O Port D. Each bit may be individually
selected to be an input or output. Each
output may be selected to be high-low
drive or open drain. Outputs are buffered
by timer-synchronizable registers for
precision edge control. PD6 can be
programmed to be an optional serial output
for serial port A. PD4 can be programmed
to be an optional serial output for serial
port B. PD7 and PD5 can be used as
alternate serial inputs by serial ports A and
B, in which case these pins should be
programmed as inputs.
43–50
I/O Port E
PE7–PE0
Input/
Output
I/O Port E. Each bit may be individually
selected to be an input or output. Outputs
are buffered by timer-synchronizable
registers for precision edge control. Each
of the port lines can be individually
selected to be an I/O control signal instead
of a parallel I/O line. Each of the 8
possible I/O control signals is a strobe
energized on an external I/O cycle to 1/8th
of the 64K external I/O space. Each strobe
can be programmed to be a chip select, a
write strobe, a read strobe or a combined
read and write strobe. Any port bit used as
an I/O control strobe must be programmed
as an output bit. If the slave port is
enabled, PE7 is used as the slave register
chip select signal (negative active). PE7
should be programmed as an input for the
slave register chip select function to work.
If PE7 is programmed as an output and set
low, then the slave register chip select will
always be activated. PE0 and PE4 serve as
alternate inputs for external interrupt 0.
PE1 and PE5 serve as alternate inputs for
external interrupt 1. If PE0 is enabled, then
PE1 must also be enabled and similarly for
PE4 and PE5. The interrupt is triggered in
software on fall, rising or both edges. If
both interrupts are enabled, they are or’ed
together after edge detection has been
performed on each input individually. The
port bits must be set up as inputs for the to
use them as interrupt request inputs.
21–26, 29, 30
Table 5-1. Rabbit Pin Descriptions (continued)
Pin Group
Pin Name
Direction
Function
Pin Numbers