T89C51RD2-3CBC-L ATMEL [ATMEL Corporation], T89C51RD2-3CBC-L Datasheet - Page 26

• Manufacturer Part Number: T89C51RD2-3CBC-L
• Description: 0 to 40MHz Flash Programmable 8-bit Microcontroller
• Manufacturer: ATMEL [ATMEL Corporation]

There are two additional registers associated with each of the PCA modules. They are CCAPnH and CCAPnL and
these are the registers that store the 16-bit count when a capture occurs or a compare should occur. When a module
is used in the PWM mode these registers are used to control the duty cycle of the output (See Table 11 & Table 12)
Rev. F - 15 February, 2001
CCAPMn Address
n = 0 - 4
a.
ECOMn
-
ECOMn
CAPPn
CAPNn
MATn
TOGn
PWMn
ECCFn
X
X
X
Symbol
0
1
1
1
1
User software should not write 1s to reserved bits. These bits may be used in future 8051 family
products to invoke new features. In that case, the reset or inactive value of the new bit will be 0, and its
active value will be 1. The value read from a reserved bit is indeterminate.
Table 9. CCAPMn: PCA Modules Compare/Capture Control Registers
CAPPn
0
1
0
1
0
0
0
0
CCAPM0=0DAH
CCAPM1=0DBH
CCAPM2=0DCH
CCAPM3=0DDH
CCAPM4=0DEH
Function
Not implemented, reserved for future use.
Enable Comparator. ECOMn = 1 enables the comparator function.
Capture Positive, CAPPn = 1 enables positive edge capture.
Capture Negative, CAPNn = 1 enables negative edge capture.
Match. When MATn = 1, a match of the PCA counter with this module's compare/capture
register causes the CCFn bit in CCON to be set, flagging an interrupt.
Toggle. When TOGn = 1, a match of the PCA counter with this module's compare/capture
register causes the CEXn pin to toggle.
Pulse Width Modulation Mode. PWMn = 1 enables the CEXn pin to be used as a pulse width
modulated output.
Enable CCF interrupt. Enables compare/capture flag CCFn in the CCON register to generate
an interrupt.
Reset value
Table 10. PCA Module Modes (CCAPMn Registers)
CAPNn
0
0
1
1
0
0
0
0
MATn
0
0
0
0
1
1
0
1
X
-
TOGn
X
0
0
0
0
0
1
0
ECOMn
0
PWMm
0
0
0
0
0
0
1
0
CAPPn
a
0
ECCFn
X
X
X
X
X
X
0
0
CAPNn
0
trigger on CEXn
CEXn
mode.
16-bit capture by a negative trigger on
16-bit capture by a transition on CEXn
No Operation
16-bit capture by a positive-edge
16-bit Software Timer / Compare
16-bit High Speed Output
8-bit PWM
Watchdog Timer (module 4 only)
MATn
0
Module Function
T89C51RD2
TOGn
0
PWMm
0
ECCFn
0
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