AT89C51RB2-RLTCM ATMEL [ATMEL Corporation], AT89C51RB2-RLTCM Datasheet - Page 39

• Manufacturer Part Number: AT89C51RB2-RLTCM
• Description: 8-bit Microcontroller with 16K/ 32K Bytes Flash
• Manufacturer: ATMEL [ATMEL Corporation]

High-speed Output Mode
Figure 14. PCA High-speed Output Mode
4180B–8051–04/03
CCAPnH
Write to
1
CCAPnL
Write to
0
In this mode the CEX output (on port 1) associated with the PCA module will toggle
each time a match occurs between the PCA counter and the modules capture registers.
To activate this mode the TOG, MAT, and ECOM bits in the modules CCAPMn SFR
must be set (see Figure 14).
A prior write must be done to CCAPnL and CCAPnH before writing the ECOMn bit.
Before enabling ECOM bit, CCAPnL and CCAPnH should be set with a non-zero value,
otherwise an unwanted match could occur.
Once ECOM is set, writing CCAPnL will clear ECOM so that an unwanted match doesn’t
occur while modifying the compare value. Writing to CCAPnH will set ECOM. For this
reason, user software should write CCAPnL first, and then CCAPnH. Of course, the
ECOM bit can still be controlled by accessing to CCAPMn register.
Reset
Enable
PCA Counter/Timer
CCAPnH
CH
16-bit Comparator
CF
ECOMn
CCAPnL
CR
CL
CAPPn
Match
CAPNn MATn TOGn PWMn ECCFn
CCF4 CCF3 CCF2 CCF1 CCF0
AT89C51RB2/RC2
CCON
0xD8
CCAPMn, n = 0 to 4
0xDA to 0xDE
PCA IT
CEXn
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