MC68HC908LB8_05 Datasheet, PDF (155/234 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Control Logic Block
Bit 7
6
5
4
3
2
1
Bit 0
Read: _{Bit 7}
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Write:
Reset:
0
0
0
0
0
0
0
0
Bold = Buffered
Figure 15-19. PWMx Value Registers Low (PVALxL)
The 16-bit signed value stored in this register determines the duty cycle of the PWM. The duty cycle is
defined as:
(PWM value/modulus) x 100
Writing a number less than or equal to 0 causes the PWM to be off for the entire PWM period. Writing a
number greater than or equal to the 12-bit modulus causes the PWM to be on for the entire PWM period.
To avoid erroneous PWM pulses, this value is buffered and will not be used by the PWM generator until
the LDOK bit has been set and the next PWM load cycle begins.
NOTE
When reading these registers, the value read is the buffer (not necessarily
the value the PWM generator is currently using).
15.8.4 PWM Control Register 1
PWM control register 1 (PCTL1) controls PWM enabling/disabling, the location of the PWM Fault bit, the
loading of new modulus, prescaler, PWM values, and the PWM correction method.
Address: $0040
Bit 7
6
5
4
3
Read:
0
FPOS PWMINT PWMF
0
Write:
Reset:
0
0
0
0
0
= Unimplemented
2
1
Bit 0
0
LDOK PWMEN
0
0
0
Figure 15-20. PWM Control Register 1 (PCTL1)
FPOS — Fault Pin Position Bit
This read/write bit allows the user to select the location of the Fault pin.
1 = Fault pin functionality is placed on PTB2
0 = Fault pin functionality is placed on PTB7
NOTE
Placing the Fault pin on PTB7 will not affect the ADC or the op
amp/comparator connections. This is to allow the output of the op
amp/comparator to be used as the input to the Fault pin and for this same
signal to be simultaneously measured by the ADC.
PWMINT — PWM Interrupt Enable Bit
This read/write bit allows the user to enable and disable PWM CPU interrupts. If set, a CPU interrupt
will be pending when the PWMF flag is set.
1 = Enable PWM CPU interrupts
0 = Disable PWM CPU interrupts
MC68HC908LB8 Data Sheet, Rev. 1
Freescale Semiconductor
155