C509-L_97 SIEMENS [Siemens Semiconductor Group], C509-L_97 Datasheet - Page 92

• Manufacturer Part Number: C509-L_97
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

6.1.2
Several pins of ports 1, 3, 4, 5 and 6 are multifunctional. They are port pins and also serve to
implement special features as listed in table 6-1.
Figure 6-11 shows 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 has to contain a one (1); otherwise the pull-down FET is on and the port pin is stuck at 0. (This
does not apply to ports 1.0 to 1.4 and ports 5.0 to 5.7 when operating in compare output mode).
After reset all port latches contain ones (1).
Figure 6-11
Circuitry of Ports 1, 3, 4, 5 and 6.0 through 6.2
Ports 6.3 through 6.7 have no alternate functions as described above. Therefore, the port circuitry
can do without the switching capability between alternate function and normal I/O operation. This
more simple circuitry is shown as basic port structure in figure 6-3.
Table 6-1 :
Alternate Functions of Port Pins
Port
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
Semiconductor Group
Alternate Functions
Int. Bus
Latch
Latch
Read
Write
Read
Pin
INT3/CC0
INT4/CC1
INT5/CC2
INT6/CC3
INT2/CC4
T2EX
CLKOUT
T2
to
Pin
Alternate Function
External interrupt 3/capture 0/compare 0
External interrupt 4/capture 1/compare 1
External interrupt 5/capture 2/compare 2
External interrupt 6/capture 3/compare 3
External interrupt 2/capture 4/compare 4
Timer 2 ext. reload trigger input
System clock output
Timer 2 external count input
D
CLK
Bit
Latch
Alternate
Function
Input
Q
Q
6-14
Alternate
Function
Output
On-Chip Peripheral Components
&
MCS01827
V
CC
Internal
Pull Up
Arrangement
Pin
1997-10-01
C509-L