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MPC555 / MPC556
TPU ROM FUNCTIONS
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
D-34
D.13 Output Compare (OC)
The output compare (OC) function generates a rising edge, falling edge, or a toggle of
the previous edge in one of three ways:
1. Immediately upon CPU initiation, thereby generating a pulse with a length equal
to a programmable delay time
2. At a programmable delay time from a user-specified time
3. Continuously. Upon receiving a link from a channel, OC references, without
CPU interaction, a specifiable period and calculates an offset:
where RATIO is a parameter supplied.
This algorithm generates a 50% duty-cycle continuous square wave with each high/
low time equal to the calculated OFFSET. Due to offset calculation, there is an initial
link time before continuous pulse generation begins. See Motorola TPU Progamming
Note
Output Compare TPU Function (OC),
(TPUPN12/D)
.
shows the host interface areas and parameter RAM for the OC function.
Offset
Period
Ratio
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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