MITSUBISHI MICROCOMPUTERS
M37274EFSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
INTERRUPTS
Interrupt Causes
Interrupts can be caused by 18 different sources consisting of 4 ex-
ternal, 12 internal, 1 software, and reset. Interrupts are vectored in-
terrupts with priorities as shown in Table 1. Reset is also included in
the table because its operation is similar to an interrupt.
When an interrupt is accepted,
(1) VSYNC and OSD interrupts
The VSYNC interrupt is an interrupt request synchronized with
the vertical sync signal.
The OSD interrupt occurs after character block display to the
CRT is completed.
(1) The contents of the program counter and processor status
register are automatically stored into the stack.
(2) INT1, INT2, INT3 interrupts
With an external interrupt input, the system detects that the level
of a pin changes from “L” to “H” or from “H” to “L,” and generates
an interrupt request. The input active edge can be selected by
bits 3, 4 and 6 of the interrupt input polarity register (address
021216) : when this bit is “0,” a change from “L” to “H” is detected;
when it is “1,” a change from “H” to “L” is detected. Note that all
bits are cleared to “0” at reset.
(2) The interrupt disable flag I is set to “1” and the corresponding
interrupt request bit is set to “0.”
(3) The jump destination address stored in the vector address enters
the program counter.
Other interrupts are disabled when the interrupt disable flag is set to
“1.”
All interrupts except the BRK instruction interrupt have an interrupt
request bit and an interrupt enable bit. The interrupt request bits are
in interrupt request registers 1 and 2 and the interrupt enable bits are
in interrupt control registers 1 and 2. Figures 11 to 15 show the inter-
rupt-related registers.
(3) Timer 1, 2, 3 and 4 interrupts
An interrupt is generated by an overflow of timer 1, 2, 3 or 4.
(4) Serial I/O interrupt
This is an interrupt request from the clock synchronous serial
I/O function.
Interrupts other than the BRK instruction interrupt and reset are ac-
cepted when the interrupt enable bit is “1,” interrupt request bit is “1,”
and the interrupt disable flag is “0.” The interrupt request bit can be
set to “0” by a program, but not set to “1.” The interrupt enable bit can
be set to “0” and “1” by a program.
(5) f(XIN)/4096 interrupt
This interrupt occurs regularly with a f(XIN)/4096 period. Set bit 0
of the PWM mode register 1 to “0.”
(6) Data slicer interrupt
An interrupt occurs when slicing data is completed.
2
Reset is treated as a non-maskable interrupt with the highest priority.
Figure 10 shows interrupt control.
(7) Multi-master I C-BUS interface interrupt
2
This is an interrupt request related to the multi-master I C-BUS
interface.
(8) A-D conversion interrupt
An interrupt occurs at the completion of A-D conversion. Since
A-D conversion interrupt and the INT3 interrupt share the same
vector, an interrupt source is selected by bit 7 of the interrupt
interval determination control register (address 021216).
Table 1. Interrupt Vector Addresses and Priority
Interrupt Source
Priority
Vector Addresses
Remarks
Reset
1
2
FFFF16, FFFE16
FFFD16, FFFC16
FFFB16, FFFA16
FFF916, FFF816
FFF716, FFF616
FFF516, FFF416
FFF316, FFF216
FFF116, FFF016
FFEF16, FFEE16
FFED16, FFEC16
FFEB16, FFEA16
FFE916, FFE816
Non-maskable
OSD interrupt
INT1 interrupt
3
Active edge selectable
Data slicer interrupt
Serial I/O interrupt
Timer 4 interrupt
4
5
6
f(XIN)/4096 interrupt
VSYNC interrupt
7
8
Active edge selectable
Timer 3 interrupt
9
Timer 2 interrupt
10
11
12
Timer 1 interrupt
A-D convertion · INT3 interrupt
Software switch by software (See note)/
When selecting INT3 interrupt, active edge selectable.
Active edge selectable
INT2 interrupt
13
14
15
16
FFE716, FFE616
FFE516, FFE416
FFE316, FFE216
FFDF16, FFDE16
2
Multi-master I C-BUS interface interrupt
Timer 5 · 6 interrupt
Software switch by software (See note)
Non-maskable (software interrupt)
BRK instruction interrupt
Note : Switching a source during a program causes an unnecessary interrupt occurs. Accordingly, set a source at initializing of program.
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RENESAS [ RENESAS TECHNOLOGY CORP ]
