SAB80C517-M16 SIEMENS [Siemens Semiconductor Group], SAB80C517-M16 Datasheet - Page 111

• Manufacturer Part Number: SAB80C517-M16
• Description: 8-Bit CMOS Single-Chip Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

On-Chip Peripheral Components
Example:
Timer 2 in auto-reload mode; contents of reload register CRC = 0FF00 H
1
Restriction of module. Range =
x 100% = 0.195%
256 x 2
This leads to a variation of the duty cycle from 0.195% to 99.805% for a timer 2/CCx register
configuration when 8 of 16 bits are used.
Compare Function of Register CC4; "Concurrent Compare"
Compare register CC4 is new in the SAB 80C517 and permanently assigned to timer 2. lt has its
own compare/capture enable register CC4EN (see figure 7-47). Register CC4 can be set to
operate as any of the other CC registers (see also figures 7-42 and 7-43). 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 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 P1.4 (which is the
standard output for register CC4) and an additional eight lines at port 5 (see figure 7-45).
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.
Figure 7-46 gives an example of how to generate eight different rectangular wave forms at port 5
using a pattern table and a time schedule for these patterns. The patterns are moved into port 5
before the corresponding timer count is reached. The (future) timer count at which the pattern shall
appear at the port must be loaded to register CC4. Thus the user can mask each port bit differently
depending on whether he wants the output to be changed or not.
Concurrent compare is enabled by setting bit COCOEN in special function register CC4EN. A ’1’ in
this bit automatically sets compare mode 1 for register CC4, too. A 3-bit field in special function
register CC4EN determines the additional number of output pins at port 5. Port P1.4/CC4/INT2 is
used as a standard output pin in any compare mode for register CC4.
Semiconductor Group
112