MC68HC908MR8 Datasheet, PDF (174/372 Pages) Motorola, Inc – Microcontrollers

Pulse-Width Modulator for Motor Control
illegal.) However, the dead-time constraints and fault conditions will still
be guaranteed.
9.12.3 PWMx Value Registers
Each of the six PWMs has a 16-bit PWM value register.
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 15
Write:
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Reset: 0
0
0
0
0
0
0
0
Figure 9-33. PWMx Value Registers High (PVALxH)
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 7
Write:
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset: 0
0
0
0
0
0
0
0
Figure 9-34. 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.
If the complementary mode is selected, the PWM pairs share PWM
value registers.
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).
Technical Data
174
MC68HC908MR8 — Rev 4.1
Pulse-Width Modulator for Motor Control (PWMMC) Freescale Semiconductor