MPC555
/
MPC556
MODULAR INPUT/OUTPUT SUBSYSTEM (MIOS1)
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
15-18
15.11 MIOS Double Action Submodule (MDASM)
The MIOS double action submodule (MDASM) provides two consecutive 16-bit input
captures or two consecutive 16-bit output compare functions that can occur automat-
ically without software intervention. The input edge detector is programmable to trigger
the capture function to occur on the desired edge. The output flip-flop is set by one of
the output compares and is reset by the other one. In all modes except disable mode,
an optional interrupt is available to the software. Software selection is provided to se-
lect which of the incoming 16-bit counter buses is used for the input capture or the out-
put compare.
The MDASM has six different software selectable modes:
• Disable mode
• Pulse width measurement
• Period measurement
• Input capture mode
• Single pulse generation
• Continuous pulse generation
The MDASM has three data registers that are accessible to the software from the var-
ious modes. For some of the modes, two of the registers are cascaded together to pro-
vide double buffering. The value in one register is transferred to the other register
automatically at the correct time so that the minimum pulse (measurement or genera-
tion) is just one 16-bit counter bus count.
Refer to
for the MDASM relative I/O pin implementation.
Table 15-15 MMCSMCR CP and
MPWMSMSCR CP Values
Prescaler Value
(CP in hex)
MIOS Prescaler Clock
Divided by
FF
1
FE
2
FD 3
FC
4
FB
5
FA
6
F9
7
F8
8
......
........
02
254 (2^8 -2)
01
255 (2^8 -1)
00
256 (2^8)
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
.
..