M37221M6_03 Datasheet, PDF (10/62 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER with ON-SCREEN DISPLAY CONTROLLER

MITSUBISHI MICROCOMPUTERS
M37221M6-XXXSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER for VOLTAGE SYNTHESIZER
with ON-SCREEN DISPLAY CONTROLLER
INTERRUPTS
Interrupts can be caused by 14 different sources consisting of 4 ex-
ternal, 8 internal, 1 software, and reset. Interrupts are vectored inter-
rupts with priorities 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) The contents of the program counter and processor status
register are automatically stored into the stack.
(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. Figure 4 shows the structure of
the interrupt-related registers.
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.
Reset is treated as a non-maskable interrupt with the highest priority.
Figure 5 shows interrupt control.
Interrupt Causes
(1) VSYNC and CRT interrupts
The VSYNC interrupt is an interrupt request synchronized with
the vertical sync signal.
The CRT interrupt occurs after character block display to the CRT
is completed.
(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 5 of the interrupt input polarity register (address
00F916) : when this bit is “0,” a change from “L” to “H” is de-
tected; when it is “1,” a change from “H” to “L” is detected. Note
that all bits are cleared to “0” at reset.
(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.
(5) f(XIN)/4096 interrupt
This interrupt occurs regularly with a f(XIN)/4096 period. Set bit 0
of the PWM output control register 1 to “0.”
(6) Multi-master I²C-BUS interface interrupt
This is an interrupt request related to the multimaster I²C-BUS
interface.
(7) BRK instruction interrupt
This software interrupt has the least significant priority. It does
not have a corresponding interrupt enable bit, and it is not af-
fected by the interrupt disable flag I (non-maskable).
Table 1. Interrupt vector addresses and priority
Interrupt source
Priority
Reset
1
CRT interrupt
2
INT2 interrupt
3
INT1 interrupt
4
Timer 4 interrupt
5
f(XIN)/4096 interrupt
6
VSYNC interrupt
7
Timer 3 interrupt
8
Timer 2 interrupt
9
Timer 1 interrupt
10
Serial I/O interrupt
11
Multi-master I²C-BUS interface interrupt
12
INT3 interrupt
13
BRK instruction interrupt
14
Vector addresses
FFFF16, FFFE16
FFFD16, FFFC16
FFFB16, FFFA16
FFF916, FFF816
FFF516, FFF416
FFF316, FFF216
FFF116, FFF016
FFEF16, FFEE16
FFED16, FFEC16
FFEB16, FFEA16
FFE916, FFE816
FFE716, FFE616
FFE516, FFE416
FFDF16, FFDE16
Remarks
Non-maskable
Active edge selectable
Active edge selectable
Active edge selectable
Active edge selectable
Non-maskable (software interrupt)
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