SAF-C515-L24M SIEMENS [Siemens Semiconductor Group], SAF-C515-L24M Datasheet - Page 29

• Manufacturer Part Number: SAF-C515-L24M
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Compare Mode 1
If compare mode 1 is enabled and the software writes to the appropriate output latch at the port, the
new value will not appear at the output pin until the next compare match occurs. Thus, it can be
chosen whether the output signal has to make a new transition (1-to-0 or 0-to-1, depending on the
actual pin-level) or should keep its old value at the time when the timer value matches the stored
compare value.
In compare mode 1 (see figure 12) the port circuit consists of two separate latches. One latch
(which acts as a "shadow latch") can be written under software control, but its value will only be
transferred to the port latch (and thus to the port pin) when a compare match occurs.
Figure 12
Compare Function in Compare Mode 1
Semiconductor Group
Compare Register
Timer Register
Compare Reg.
Timer Circuit
Comparator
Circuit
16 Bit
16 Bit
Compare
Match
Port Circuit
Internal
Bus
Write to
Latch
29
D
CLK
Shadow
Latch
Read Latch
Q
D
CLK
Latch
Port
Read Pin
Q
Q
V
CC
MCS02662
1997-08-01
Port
Pin
C515