MITSUBISHI MICROCOMPUTERS
M37274EFSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
DISPLAY OSCILLATION CIRCUIT
ADDRESSING MODE
The OSD oscillation circuit has a built-in clock oscillation circuits, so
that a clock for OSD can be obtained simply by connecting an LC, a
ceramic resonator, or a quartz-crystal oscillator across the pins OSC1
and OSC2. Which of the sub-clock or the OSD oscillation circuit is
selected by setting bits 5 and 4 of the clock source control register
(address 021616).
The memory access is reinforced with 17 kinds of addressing modes.
Refer to SERIES 740 <Software> User’s Manual for details.
MACHINE INSTRUCTIONS
There are 71 machine instructions. Refer to SERIES 740 <Soft- ware>
User’s Manual for details.
PROGRAMMING NOTES
(1) The divide ratio of the timer is 1/(n+1).
(2) Even though the BBC and BBS instructions are executed imme-
diately after the interrupt request bits are modified (by the pro-
gram), those instructions are only valid for the contents before
the modification. At least one instruction cycle is needed (such as
an NOP) between the modification of the interrupt request bits
and the execution of the BBC and BBS instructions.
OSC1
OSC2
L
C1
C2
(3) After the ADC and SBC instructions are executed (in the decimal
mode), one instruction cycle (such as an NOP) is needed before
the SEC, CLC, or CLD instruction is executed.
(4) An NOP instruction is needed immediately after the execution of
a PLP instruction.
Fig. 111. Display Oscillation Circuit
(5) In order to avoid noise and latch-up, connect a bypass capacitor
(≈ 0.1 mF) directly between the VCC pin–VSS pin, AVCC pin–VSS
pin, and the VCC pin–CNVSS pin, using a thick wire.
AUTO-CLEAR CIRCUIT
When a power source is supplied, the auto-clear function will oper-
______
ate by connecting the following circuit to the RESET pin.
Circuit example 1
Vcc
RESET
Vss
Circuit example 2
RESET
Vcc
Vss
Note : Make the level change from “L” to “H” at the point at
which the power source voltage exceeds the specified
voltage.
Fig. 112. Auto-clear Circuit Example
106