C508_01 Datasheet, PDF (72/267 Pages) Infineon Technologies AG – 8-Bit CMOS Microcontroller

C508
On-Chip Peripheral Components
6.1.2.2 Port 1, Port 3, and Port 5 Circuitry
The pins of Ports 1, 3, and 5 are multifunctional. They are port pins and also serve to
implement special features as listed in Table 6-2.
Figure 6-4 is a functional diagram of a port latch with alternate function. To pass the
alternate function to the output pin and vice versa, however, the gate between the latch
and driver circuit must be open. Thus, to use the alternate input or output functions, the
corresponding bit latch in the port SFR must contain a one (1); otherwise, the pull-down
FET is on and the port pin is stuck at ‘0’. After reset, all port latches contain ones (1).
Read
Latch
Alternate
Output
Function
Int. Bus
Write
to
Latch
Read
Pin
D
Q
&
Bit
Latch
CLK
Q
Alternate
Input
Function
Figure 6-4 Ports 1, 3, and 5 Circuitry
V_DD
Internal
Pull Up
Arrangement
Port
Pin
MCS04044
User’s Manual
6-7
2001-05