AT89C5131-PLTIL ATMEL Corporation, AT89C5131-PLTIL Datasheet - Page 63

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AT89C5131-PLTIL

Manufacturer Part Number
AT89C5131-PLTIL
Description
8-bit Flash Microcontroller with Full Speed USB Device
Manufacturer
ATMEL Corporation
Datasheet
Figure 29. PCA High-speed Output Mode
Pulse Width Modulator
Mode
4136B–USB–09/03
CCAPnH
Write to
1
CCAPnL
Write to
0
Reset
Enable
Before enabling ECOM bit, CCAPnL and CCAPnH should be set with a non zero value,
otherwise an unwanted match could happen.
Once ECOM 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.
All of the PCA modules can be used as PWM outputs. Figure 30 shows the PWM func-
tion. The frequency of the output depends on the source for the PCA timer. All of the
modules will have the same frequency of output 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 mod-
ule's CCAPLn SFR the output will be low, when it is equal to or greater than the output
will be high. When CL overflows from FF to 00, CCAPLn is reloaded with the value in
CCAPHn. This allows updating the PWM without glitches. The PWM and ECOM bits in
the module's CCAPMn register must be set to enable the PWM mode.
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
CCON
0xD8
CCAPMn, n = 0 to 4
0xDA to 0xDE
AT89C5131
PCA IT
CEXn
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