C502
Pin Definitions and Functions
Symbol
P1.7 – P1.0
Pin Number
P-LCC-44 P-DIP-40
9–2
8–1
I/O*) Function
I
Port 1
is a bidirectional I/O port with internal pull-up
resistors. Port 1 pins that have 1s written to
them are pulled high by the internal pull-up
resistors, and in that state can be used as
inputs. As inputs, port 1 pins being externally
pulled low will source current (IIL, in the DC
characteristics) because of the internal pull-up
resistors. Port 1 also contains the timer 2 pins
as secondary function. The output latch corre-
sponding to a secondary function must be pro-
grammed to a one (1) for that function to
operate.
The secondary functions are assigned to the
pins of port 1, as follows:
2
1
3
2
P1.0 T2 Input to counter 2
P1.1 T2EX Capture - Reload trigger of
timer 2 / Up-Down count
*) I = Input
O = Output
Semiconductor Group
7