C509-L_97 Datasheet, PDF (89/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

On-Chip Peripheral Components
C509-L
6.1.1.3.2 Output Mode
The output mode for a port pin is selected by programming the corresponding direction bit to '0'
(QDL='0'). The contents of the port latch determines whether a '1' (QPL='0') or a '0' (QPL='1') is
driven. Figure 6-8 shows the port structure in the output mode driving a '1' while figure 6-9
illustrates the port structure in the output mode driving a '0'.
Figure 6-8
Bidirectional Port Structure - Output Mode - “1”
The FET n1 is switched off. FET p1 is activated for one state (dashed lines) if a 0-to-1 transition is
programmed to the port pin, i.e. a '1' is programmed to the port latch which contained a '0'. The FETs
p2, p3 are both active and are driving the '1' at the port pin.
Semiconductor Group
6-11
1997-10-01