M37754 Mitsubishi, M37754 Datasheet - Page 62

• Manufacturer Part Number: M37754
• Description: SINGLE-CHIP 16BIT CMOS MICROCOMPUTER
• Manufacturer: Mitsubishi

RESET CIRCUIT
Reset is released when the RESET pin is returned to “H” level after
holding it at “L” level while the supply voltage is at 5V ±10%. As the
result, program execution starts at the address formed by setting the
address A
and A
Figure 76 shows the status of the internal registers during reset.
Figure 77 shows an example of a reset circuit. When a stabilized
clock is input from the external to the oscillation circuit, the reset in-
put voltage must be held 0.9V or lower when the supply voltage
reaches 4.5V. When connecting a resonator to the oscillation circuit,
return the reset input voltage from “L” to “H” after the main-clock os-
cillation is fully stabilized
Fig. 77 Reset circuit example (perform careful evaluation at system
62
7
RESET
–A
design before using)
0
23
to the contents of address FFFE
–A
16
to 00
16
V
CC
, A
15
______
–A
RESET
V
8
CC
to the contents of address FFFF
0 V
0 V
16
.
Power on
4.5V
0.9V
M37754M8C-XXXGP, M37754M8C-XXXHP
16
,
INPUT/OUTPUT PINS
Ports P0 to P11 all have the direction register and each bit can be
programmed for input or output. A pin becomes an output pin when
the corresponding bit of direction register is “1”, and an input pin
when it is “0”.
When a pin is programmed for output, the data is written to its port
latch and it is output to the output pin. When a pin is programmed for
output, the contents of the port latch is read instead of the value of
the pin. Accordingly, a previously output value can be read correctly
even when the output “H” voltage is lowered or the output “L” voltage
is raised owing to an external load and others.
A pin programmed as an input pin is floating, and the value input to
the pin can be read. When a pin is programmed as an input pin, the
data is written only in the port latch and the pin remains floating.
Additionally, ports P9
pull-up function of ports is selected with bits 7 and 6 of the particular
function select register 1. Refer to the section on Interrupts for the
pull-up function.
Figures 78 and 79 show block diagrams of ports P0 to P11 in the
single-chip mode and E output.
Ports P0 to P4, P10 and P11 are also used as pins of address, data
and control signals. Refer to the section on Processor mode for more
details.
M37754S4CGP, M37754S4CHP
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
5
_
, P5
MITSUBISHI MICROCOMPUTERS
4
to P5
7
include pull-up transistors. The