MPC555 / MPC556
TPU ROM FUNCTIONS
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
D-4
TPUMCR 2. It is good practice always to initialize any write once register to ensure
an incorrect value is not accidentally written.
The descriptions below document the functions listed in
(Bank 0) and
(Bank 1) of the TPU3 ROM module.
D.2 Programmable Time Accumulator (PTA)
PTA accumulates a 32-bit sum of the total high time, low time, or period of an input
signal over a programmable number of periods or pulses. The period accumulation
can start on a rising or falling edge. After the specified number of periods or pulses,
the PTA generates an interrupt request.
From one to 255 period measurements can be accumulated before the TPU interrupts
the CPU, providing instantaneous or average frequency measurement capability. See
Motorola TPU Progamming Note
Programmable Time Accumulator TPU Function
(PTA),
(TPUPN06/D)
.
shows all of the host interface areas for the PTA function.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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