C509-L_97 Datasheet, PDF (133/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

On-Chip Peripheral Components
C509-L
6.3.4.3 Compare Function of Register CC4; “Concurrent Compare”
Compare register CC4 is permanently assigned to timer 2. lt has its own compare/capture enable
register CC4EN. Register CC4 can be set to operate as any of the other CC registers (see also
figures 6-29 and 6-30). Its output pin is P1.4/CC4/INT2 and it has a dedicated compare mode select
bit COMO located in register CC4EN.
In addition to the standard operation in compare mode 0 or 1, there is another feature called
‘concurrent compare’ which is just an application of compare mode 1 to more than one output pin.
Concurrent compare means that the comparison of CC4 and timer 2 can manipulate up to nine port
pins concurrently. A standard compare register in compare mode 1 normally transfers a
preprogrammed signal level, which is stored in the shadow latch to a single output line. Register
CC4, however, is able to put a 9-bit pattern to nine output lines. The nine output lines consist of one
line at port 1 (P1.4), which is the standard output for register CC4, and additional eight lines at port 5
(see figure 6-29).
Concurrent compare is an ideal and effective option where more than one synchronous output
signal is to be generated. Applications including this requirement could among others be a complex
multiple-phase stepper motor control as well as the control of ignition coils of a car engine. All these
applications have in common that predefined bit-patterns must be put to an output port at a precisely
predefined moment. This moment refers to a special count of timer 2, which was loaded to compare
register CC4.
Compare Register CC4
16 Bit
Comparator
16 Bit
TH2
TL2
Timer 2
To Interrupt Logic
Port 5-Shadow Latch
COCON 1
COCON 2
COCON 3
P5.0/
CCM0
Port 5-Output Buffer
Figure 6-29
“Concurrent Compare” Function of Register CC4
P1.4
S.L.
COMO
P5.7/ P1.4/
CCM7 INT2/
CC4
MCS02666
Semiconductor Group
6-55
1997-10-01