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MPC555 / MPC556
MODULAR INPUT/OUTPUT SUBSYSTEM (MIOS1)
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
15-1
SECTION 15
MODULAR INPUT/OUTPUT SUBSYSTEM (MIOS1)
The modular I/O system (MIOS) consists of a library of flexible I/O and timer functions
including I/O port, counters, input capture, output compare, pulse and period measure-
ment, and PWM. Because the MIOS is composed of submodules, it is easily config-
urable for different kinds of applications. MIOS1 is the implementation of the MIOS
architecture used in the MPC555 / MPC556.
The MIOS1 is composed of the following submodules:
• One MIOS bus interface submodule (MBISM)
• One MIOS counter prescaler submodule (MCPSM)
• Two MIOS modulus counter submodules (MMCSM)
• 10 MIOS double action submodules (MDASM)
• Eight MIOS pulse width modulation submodules (MPWMSM)
• One MIOS 16-bit parallel port I/O submodule (MPIOSM)
• Two MIOS interrupt request submodules (MIRSM)
15.1 MIOS1 Features
The basic features of the MIOS1 are as follows:
• Modular architecture at the silicon implementation level
• Disable capability in each submodule to allow power saving when its function is
not needed
• Two 16-bit buses to allow action submodules to use counter data
• When not used for timing functions, every channel pin can be used as a port pin:
I/O, output only or input only, depending on the channel function
• Submodules pin status bits:
• MIOS counter prescaler submodule (MCPSM):
— Centralized counter clock generator
— Programmable 4-bit modulus down-counter
— Wide range of possible division ratios: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15 and 16
— Count inhibit under software control
• Two MIOS modulus counter submodules (MMCSM), each with these features:
— Programmable 16-bit modulus up-counter with built-in programmable 8-bit
prescaler clocked by MCPSM output
— Maximum increment frequency of the counter:
• clocked by the internal Counter Clock: F
SYS
/2
• clocked by the external pin: F
SYS
/4
— Flag setting and possible interrupt generation on overflow of the up-counter
— Time counter on internal clock with interrupt capability after a pre-determined
time
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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