Rainbow Electronics T89C5121 User Manual
Page 7
7
A/T8xC5121
4164G–SCR–07/06
I/O
Input/Output function
P3.4 is a bi-directional I/O port with internal pull-ups.
I
Timer 0 function: External clock input
When Timer 0 operates as a counter, a falling edge on the T0 pin
increments the count.
Z
Reset configuration
High impedance due to PMOS switched OFF
P3.5
CIO1
DV
CC
I/O
Alternate card function
Card I/O
I/O
Input/Output function
P3.5 is a bi-directional I/O port with internal pull-ups.
I
Timer 1 function: External clock input
When Timer 1 operates as a counter, a falling edge on the T1 pin
increments the count.
I
Reset configuration
Input (high level due to internal pull-up)
P3.6
CCLK1
LED0
DV
CC
O
Alternate card function
Card clock
O
LED function
These pins can be directly connected to the cathode of standard
LED without external current limiting resistors. The typical current
of each output can be programmed by software to 2, 4 or 10 mA
(LEDCON register).
I/O
Input/Output function
P3.6 is a LED port.
I
Reset configuration
Input at high level
P3.7
CRST1
DV
CC
O
Alternate card function
Card reset
P3.7
CRST1
LED1
DV
CC
O
LED function
These pins can be directly connected to the cathode of standard
LED without external current limiting resistors. The typical current
of each output can be programmed by software to 2, 4 or 10 mA
(LEDCON register).
I/O
Input/Output function
P3.7 is a a LED port.
I
Reset configuration
Input at high level
Table 1. Ports Description (Continued)
Port
Signal
Name
Alternate
Internal
Power
Supply
ESD
Type
Description