AN2527 Freescale Semiconductor / Motorola, AN2527 Datasheet - Page 14

• Manufacturer Part Number: AN2527
• Description: DC Motor with Dead-Time Correction - XOR version TPU Function Set
• Manufacturer: Freescale Semiconductor / Motorola

AN2527/D
Synchronization
signal for DC Motor
with Dead-Time
Correction – XOR
version
(DCmDtXor_sync)
Synchronized Change
of PWM Prescaler
And Synchronization
Signal Prescaler
14
DC Motor with Dead-Time Correction – XOR version TPU Function Set (DCmDtXor) MOTOROLA
The DCmDtXor_sync TPU function uses information obtained from
DCmDtXor_C and DCmDtXor_T functions, the actual PWM center times and
the PWM periods. This allows a signal to be generated, that tracks the changes
in the PWM period and is always synchronized with the PWM. The
synchronization signal is a positive pulse generated repeatedly after the
prescaler or presc_copy PWM periods (see next paragraph). The low to high
transition of the pulse can be adjusted by a parameter, either negative or
positive, to go before or after the PWM period center time of a number of TCR1
TPU cycles. The pulse width pw is another synchronization signal parameter.
The DCmDtXor_sync TPU function actually uses the presc_copy parameter
instead of the prescaler parameter. The prescaler parameter holds the
prescaler value that is copied to the presc_copy by the DCmDtXor_bottom
function at the time of the PWM parameters reload. This ensures that new
prescaler values for the PWM signals, as well as the synchronization signal, are
applied at the same time. Write the synchronization signals prescaler
parameter address to the sync_presc_addr parameter to enable this
mechanism. Write 0 to disable it, and remember to set the synchronization
signal presc_copy parameter instead of the prescaler parameter in this case.
move > 0
move > 0
prescaler = 1
prescaler = 1
move < 0
move < 0
prescaler = 2
prescaler = 2
Freescale Semiconductor, Inc.
For More Information On This Product,
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Figure 7. Synchronization signal adjustment examples
center_time
center_time
center_time
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pw
pw
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pw
pw
center_time
center_time
center_time
center_time
center_time
center_time
T
T
T
T
T
T
center_time
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T