mc68hc908lb8 Freescale Semiconductor, Inc, mc68hc908lb8 Datasheet - Page 146

• Manufacturer Part Number: mc68hc908lb8
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Pulse Width Modulator with Fault Input (PWM)
15.4 PWM Generators
Pulse-width modulator (PWM) generators are discussed in this subsection.
15.4.1 Load Operation
To help avoid erroneous pulse widths and PWM periods, the modulus, prescaler, and PWM value
registers are buffered. New PWM values, counter modulus values, and prescalers can be loaded from
their buffers into the PWM module every one, two, four, or eight PWM cycles. LDFQ1 and LDFQ0 in PWM
control register 2 are used to control this reload frequency, as shown in
arrives, regardless of whether an actual reload occurs (as determined by the LDOK bit), the PWM reload
flag bit in PWM control register 1 will be set. If the PWMINT bit in PWM control register 1 is set, a CPU
interrupt request will be generated when PWMF is set. Software can use this interrupt to calculate new
PWM parameters in real time for the PWM module.
146
Reload Frequency Bits
PRSC1 and PRSC0
LDFQ1 and LDFQ0
Prescaler Bits
Table 15-2. PWM Reload Frequency
00
01
10
11
00
01
10
11
MC68HC908LB8 Data Sheet, Rev. 1
Table 15-1. PWM Prescaler
PWM Clock Frequency
PWM Reload Frequency
Every 2 PWM cycles
Every 4 PWM cycles
Every 8 PWM cycles
BUSCLK/2
BUSCLK/4
BUSCLK/8
Every PWM cycle
BUSCLK
Table
15-2. When a reload cycle
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