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MPC555
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MPC556
MODULAR INPUT/OUTPUT SUBSYSTEM (MIOS1)
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
15-43
Figure 15-12 MIOS1 Example: Pulse Width Modulation Output
15.15.5 MIOS1 Input Pulse Accumulation
Counting the number of pulses on an input signal is another capability of the MIOS1.
Pulse accumulation uses an MMCSM. Since the counters in the counter submodules
are software accessible, pulse accumulation does not require the use of an action sub-
module. The pulse accumulation can operate continuously, interrupting only on binary
overflow of the 16-bit counter. When an MMCSM is used, an interrupt can instead be
created when the pulse accumulation reaches a preprogrammed value. To do that, the
two’s complement of the value is put in the modulus register and the interrupt occurs
when the counter overflows.
15.16 MIOS1 Configuration
The complete MIOS1 submodule and pin configuration is shown in
16-bit Up-Counter
Submodule Bus
16-bit Compare B
Output
Flip-Flop
Output
Pin
16-bit Compare A
16-bit Register B2
16-bit Register A
Output
Compare
Interrupt
on
Bus
From
Prescaler
or Pin
Leading
16-bit Register B1
Edge
Modulus Register
Modulus
Control
Clock
Select
Load
Select
Two
16-bit
Counter
Buses
MIOS Double Action Submodule
in OCAB mode (MOD3 – MOD0 = 0b0101)
MIOS Modulus Counter Submodule
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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