Modular Input/Output Subsystem (MIOS14)
MPC561/MPC563 Reference Manual, Rev. 1.2
17-72
Freescale Semiconductor
shows a counter submodule and a DASM combination as an example of period
measurement. The software designates whether the rising or falling edge of the input signal is to be used
for the measurements. When the edge is detected, the state of the 16-bit counter bus is stored in register A
and the content of register B1 is transferred to register B2. After register B2 is safely latched, the content
of register A is transferred to register B1. This procedure gives the software coherent current and previous
samples in registers A and B2 at all times. An interrupt is available for the cases where the software needs
to be aware of each new sample. Note that a software option is provided to also generate an interrupt after
the first edge.
Figure 17-44. MIOS14 Example: Double Capture Period Measurement
17.13.3 MIOS14 Double Edge Single Output Pulse Generation
Software can initialize the MIOS14 to generate both the rising and the falling edge of an output pulse. With
a MDASM, pulses as narrow as 50 ns can be generated since software action is not needed between the
edges. Pulses as long as 2.1 s can be generated. When an interrupt is desired, it can be selected to occur on
every edge or only after the second edge.
shows how a counter submodule and a MDASM can be used to generate both edges of a
single output pulse. The software puts the compare value for one edge in register A and the other one in
register B2. The MDASM automatically creates both edges and the pulse can be selected by software to
be a high-going or a low-going. After the trailing edge, the MDASM stops to await further commands from
the software. Note that a single edge output can be generated by writing to only one register.
16-bit Up-Counter
Submodule Bus
Clock
Select
16-bit Register B1
Edge
Detect
Input
Signal
16-bit Register B2
Input
Capture
Interrupt
on
From
Prescaler
or Pin
Designated
Bus
Select
Edge
16-bit Register A
Two
16-bit
Counter
Buses
MIOS14 Modulus Counter Submodule
MIOS14 Double Action Submodule
in IPM mode (MOD3-MOD0 = 0b0010)
Summary of Contents for MPC561
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Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
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Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...
