T89C51CC01 Atmel, T89C51CC01 Datasheet - Page 126

• Manufacturer Part Number: T89C51CC01
• Description: Enhanced 8-Bit Microcontroller
• Manufacturer: Atmel

High Speed Output Mode
Figure 57. PCA High Speed Output Mode
Pulse Width Modulator
Mode
126
CCAPnL
Write to
T89C51CC01
“0”
CCAPnH
Write to
“1”
Reset
Enable
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 module’s capture registers.
To activate this mode the TOG, MAT, and ECOM bits in the module’s CCAPMn SFR
must be set.
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 with-
out 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
PCA IT
CEXn
4129K–CAN–01/05