AN1965 Freescale Semiconductor / Motorola, AN1965 Datasheet - Page 11

• Manufacturer Part Number: AN1965
• Description: Design of Indirect Power Using the 56F800/E
• Manufacturer: Freescale Semiconductor / Motorola

11
6.2 Milestone Generation
The reference voltage value is corrected during the period of input voltage to provide the input current
waveform illustrated in
zero-crossing pulse length and synchronizes the processes of milestone generation with input
frequency; see
time_base
The resolved value defines the first milestone point, a timer interrupt on the output compare event.
Each time the output compare matches the interrupt, the compare register accrues toward the next
milestone. Milestone generation time intervals are stored in the Milestone Time Table. They have
constant values during the half-period of input voltage. The Output Compare Event service routine
rising-edge
arrival time
Callback Table
Time Table
Milestone
Zero-crossing Signal
Milestone
Input Capture Event
Reset Pointers
Figure
Figure 6-2. Milestones Synchronization Algorithm
MILESTONE_OFFSET
6-2.
Freescale Semiconductor, Inc.
Figure
falling-edge
arrival time
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Indirect Power Factor Correction
Figure 6-3. Milestone Generation
3-1. When the zero-crossing signal comes, the program calculates the
time_table_ptr
callback_table_ptr
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f()
Update Output Compare Register
Output Compare Match
pulse_length
Execute Milestone Callback
Output Compare Interrupt
Increment Pointer
Increment Pointer
compare_value
Software Design