mc68hc908mr8 Freescale Semiconductor, Inc, mc68hc908mr8 Datasheet - Page 150

• Manufacturer Part Number: mc68hc908mr8
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Pulse-Width Modulator for Motor Control
Technical Data
150
NOTE:
To prevent a partial reload of PWM parameters from occurring while the
software is still calculating them, an interlock bit controlled from software
is provided. This bit informs the PWM module that all the PWM
parameters have been calculated, and it is okay to use them. A new
modulus, prescaler, and/or PWM value cannot be loaded into the PWM
module until the LDOK bit in PWM control register 1 is set. When the
LDOK bit is set, these new values are loaded into a second set of
registers and used by the PWM generator at the beginning of the next
PWM reload cycle as shown in
Figure
When the PWM module is enabled (via the PWMEN bit), a load will occur
if the LDOK bit is set. Even if it is not set, an interrupt will occur if the
PWMINT bit is set. To prevent this, the software should clear the
PWMINT bit before enabling the PWM module.
Pulse-Width Modulator for Motor Control (PWMMC)
COUNTER
UP/DOWN
PWM VALUE= 1
PWM
MODULUS = 3
9-10. After these values are loaded, the LDOK bit is cleared.
PWMF SET
PWM RELOAD
LDOK = 1
Figure 9-7. Center-Aligned PWM Value Loading
Figure 9-6. PWM Interrupt Requests
PWM VALUE= 2
MODULUS = 3
PWMF SET
LDOK = 0
V
DD
LDFQ1:LDFQ0 = 00 (RELOAD EVERY CYCLE)
D
CK
Figure
LATCH
RESET
PWM VALUE= 2
MODULUS = 3
PWMF SET
LDOK = 1
9-7,
PWMF
Figure
PWMINT
MC68HC908MR8 — Rev 4.1
PWM VALUE= 1
MODULUS = 3
PWMF SET
Freescale Semiconductor
LDOK = 0
9-8,
Figure
READ PWMF AS 1,
WRITE PWMF AS 0
OR RESET
CPU INTERRUPT
REQUEST
9-9, and