Real time Port
deeopmen
Preliminary Specifications REV.E
Specifications in this manual are tentative and subject to change.
Mitsubishi microcomputers
M30220 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
85
Real time Port
When real time port output is selected, the real time port data written to the port Pm register is latched into
the real time port latch each time the corresponding timer Ai underflows, with the data output from each
corresponding port. The real time port data is written to the corresponding port Pm register. When the real
time port mode select bit changes state from “0” to “1”, the value of the real time port latch becomes “0”,
which is output from the corresponding pin. It is when timer Ai underflows first that the real time port data is
output. If the real time port data is modified when the real time port function is enabled, the modified value
is output when timer Ai underflows next time. The port functions as an ordinary port when the real time port
function is disabled.
Make sure timer Ai for real time port output is set for timer mode, and is set to have “no gate function” using
the gate function select bit. Also, before setting the real time port mode select bit to “1”, temporarily turn off
the timer Ai used and write its set value to the timer Ai register. Figure 1.14.1 shows the block diagram for
real time port output. Figure 1.14.2 shows the real time control register.
Figure 1.14.1. Block diagram for real time port output
Timer mode
TAi
IN
Timer Ai
f
1
f
8
f
32
f
C132
Timer Ai interrupt
Noise
filter
Timer Bj overflow
Port
latch
T
D
Port
latch
T
D
Data bus
Data bus
Q
Q
Pm7
Pm0
Timer Ai+1
overflow
Timer Ak
overflow
j=2, k=4, 0, m=0, 1 when i=0, 1
j=5, k=7, 5, m=2, 12 when i=5, 6
Pm4 to Pm7 real time
port mode select bit
Port
latch
T
D
Data bus
Q
Pm3
Pm
0
to Pm
3
real time port
mode select bit
Port
latch
T
D
Data bus
Q
Pm4
Timer Ai mode register's set value used in real time port
0
0
0
0
b0
b7
b6
b5
b4
b3
b2
b1
Timer Ai mode register (Addresses 0356
16
, 0357
16
, 0396
16
and 0397
16)
Real time port latch
Pm
4
to Pm
7
real time port
mode select bit
Pm
0
to Pm
3
real time port
mode select bit