SST89V54RD2 Silicon Storage Technology, Inc., SST89V54RD2 Datasheet - Page 50

• Manufacturer Part Number: SST89V54RD2
• Description: Flashflex51 Mcu
• Manufacturer: Silicon Storage Technology, Inc.

Data Sheet
8.3.2 16-Bit Software Timer Mode
The 16-bit software timer mode is used to trigger interrupt
routines, which must occur at periodic intervals. It is setup
by setting both the ECOM and MAT bits in the module’s
CCAPMn register. The PCA timer will be compared to the
module’s capture registers (CCAPnL and CCAPnH) and
when a match occurs, an interrupt will occur, if the CCFn
(CCON SFR) and the ECCFn (CCAPMn SFR) bits for the
module are both set.
©2007 Silicon Storage Technology, Inc.
Write to
CCAPnH
FIGURE
1
CCAPnL
Write to
8-3: PCA Compare Mode (Software Timer)
0
Reset
Enable
CCAPnH
PCA Timer/Counter
16-bit Comparator
CH
CF
CCAPnL
ECOMn CAPPn CAPNn MATn
CR
CL
0
50
Match
If necessary, a new 16-bit compare value can be loaded
into CCAPnH and CCAPnL during the interrupt routine.
The user should be aware that the hardware temporarily
disables the comparator function while these registers are
being updated so that an invalid match will not occur. Thus,
it is recommended that the user write to the low byte first
(CCAPnL) to disable the comparator, then write to the high
byte (CCAPnH) to re-enable it. If any updates to the regis-
ters are done, the user may want to hold off any interrupts
from occurring by clearing the EA bit. (See Figure 8-3)
CCF4
SST89V54RD2/RD / SST89V58RD2/RD
0
CCF3
TOGn
CCF2
0
PWMn ECCFn
CCF1
0
CCF0
1255 F25.0
FlashFlex MCU
CCON
CCAPMn
S71255-10-000
n=0 to 4
PCA Interrupt
12/07