AT89C51RB2-RLTCM View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

AT89C51RB2-RLTCM

8-bit Microcontroller with 16K/32K Bytes Flash

Atmel Corporation 

AT89C51RB2/RC2

High-speed Output Mode

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 15).

A prior write must be done to CCAPnL and CCAPnH before writing the ECOMn bit.

Figure 15. PCA High-speed Output Mode

Write to

CCAPnL Reset

CF CR

Write to

CCAPnH

CCAPnH

CCAPnL

CCON

CCF4 CCF3 CCF2 CCF1 CCF0 0xD8

PCA IT

1

0

Enable

16-bit Comparator

Match

CH

CL

CEXn

PCA Counter/Timer

CCAPMn, n = 0 to 4

ECOMn CAPPn CAPNn MATn TOGn PWMn ECCFn 0xDA to 0xDE

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.

41

4180E–8051–10/06

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