pc87591l National Semiconductor Corporation, pc87591l Datasheet - Page 149

• Manufacturer Part Number: pc87591l
• Description: Lpc Mobile Embedded Controllers
• Manufacturer: National Semiconductor Corporation

Revision 1.07
Embedded Controller Modules
Cycle Time Register (CTR)
The CTR register controls the cycle time and duty cycle steps, CTR is set (FF
Location: 00 FD02
Type: R/W
Duty Cycle Registers 0 to 7 (DCRi)
The DCRi (i = 0 to 7) registers control the duty cycle of PWMi output signal. DCRi is cleared (00
Location: Channel 0 - 00 FD08
Type: R/W
Bit
Name
Reset
Bit
Name
Reset
7-0
7-0
Bit
Bit
Cycle Time Value. The 8-bit down-counter divides the pre-scaler output clock by the number defined by
CTR(7:0) + 1. For example, a value of 0016 results in a divide by 1, a value of FF16 results in a divide by 256.
The contents of this register may be changed only when the PWM module is in Low Power mode. Otherwise,
there may be unpredictable results.
Duty Cycle Value. DCRi register defines the number of clocks for which PWMi is high (from the full cycle of the
PWMi cycle), when Inverse PWMi bit in PWM Polarity register is 0.
If the DCRi value > CTR value, PWMi signal is always low.
If DCRi value == CTR value, PWMi signal is always high.
When Inverse PWMi bit is 1, the value of PWMi is inverse.
Channel 1 - 00 FD0A
Channel 2 - 00 FD0C
Channel 3 - 00 FD0E
Channel 4 - 00 FD10
Channel 5 - 00 FD12
Channel 6 - 00 FD14
Channel 7 - 00 FD16
16
7
1
7
0
16
16
16
16
16
16
16
16
6
1
6
0
(Continued)
5
1
5
0
Description
Description
149
4
1
4
0
DCRi7-0
CTR7-0
3
1
3
0
16
) on reset.
0
2
1
2
16
) on reset.
1
1
1
0
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0
1
0
0