T89C51AC2-RLSI-M datasheet(80/117 Pages) ATMEL

Part #	T89C51AC2-RLSI-M

Description	8-bit MCU with 32K bytes Flash, 10 bits A/D and EEPROM

PDF	117 Pages

Scroll/Zoom	100%

Manufacturer	ATMEL [ATMEL Corporation]

Direct Link	http://www.atmel.com

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80 / 117 page

Draft.A - March 30, 2001

Preview - Confidential

T89C51AC2

15.6. Pulse Width Modulator Mode

All the PCA modules can be used as PWM outputs. The output frequency depends on the source for the PCA

timer. All the modules will have the same output frequency because they all share the PCA timer. The duty cycle

of each module is independently variable using the module’s capture register CCAPLn. When the value of the

PCA CL SFR is less than the value in the module’s CCAPLn SFR the output will be low, when it is equal to or

greater than it, the output will be high. When CL overflows from FF to 00, CCAPLn is reloaded with the value

in CCAPHn. the allows the PWM to be updated without glitches. The PWM and ECOM bits in the module’s

CCAPMn register must be set to enable the PWM mode.

Figure 69. PCA PWM Mode

CL rolls over from FFh TO 00h

loads

CCAPnH

contents

into

CCAPnL

CCAPxL

CCAPn

8-Bit

Comparator

CL (8 bits)

“0

“1”

CL < CCAPnL

CL >= CCAPnL

CEX

ECOMn0 00

0PWMn0

CCAPMn Register

T89C51AC2-RLSI-M Datasheet(PDF) 80 Page - ATMEL Corporation