4559 Datasheet, PDF (23/148 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4559 Group
INTERRUPT FUNCTION
The interrupt type is a vectored interrupt branching to an
individual address (interrupt address) according to each interrupt
source. An interrupt occurs when the following 3 conditions are
satisfied.
• An interrupt activated condition is satisfied (request flag =
“1”)
• Interrupt enable bit is enabled (“1”)
• Interrupt enable flag is enabled (INTE = “1”)
Table 10 shows interrupt sources. (Refer to each interrupt request
flag for details of activated conditions.)
(1) Interrupt enable flag (INTE)
The interrupt enable flag (INTE) controls whether the every
interrupt enable/disable. Interrupts are enabled when INTE flag
is set to “1” with the EI instruction and disabled when INTE flag
is cleared to “0” with the DI instruction. When any interrupt
occurs, the INTE flag is automatically cleared to “0,” so that
other interrupts are disabled until the EI instruction is executed.
(2) Interrupt enable bit
Use an interrupt enable bit of interrupt control registers V1 and
V2 to select the corresponding interrupt or skip instruction.
Table 11 shows the interrupt request flag, interrupt enable bit and
skip instruction.
Table 12 shows the interrupt enable bit function.
Table 10 Interrupt sources
Priority
level
Interrupt source
Interrupt name
Activated
condition
1 External 0
interrupt
Level change of
INT0 pin
2 Timer 1 interrupt Timer 1
underflow
3 Timer 2 interrupt Timer 2
underflow
4 Timer 3 interrupt Timer 3
underflow
Interrupt
address
Address 0
in page 1
Address 4
in page 1
Address 6
in page 1
Address 8
in page 1
Table 11 Interrupt request flag, interrupt enable bit
and skip instruction
Interrupt name
Interrupt
request
flag
External 0 interrupt EXF0
Timer 1 interrupt T1F
Timer 2 interrupt T2F
Timer 3 interrupt T3F
Skip
Interrupt
instruction enable bit
SNZ0
V10
SNZT1 V12
SNZT2 V13
SNZT3 V20
(3) Interrupt request flag
When the activated condition for each interrupt is satisfied, the
corresponding interrupt request flag is set to “1.” Each interrupt
request flag except the voltage drop detection circuit interrupt
request flag is cleared to “0” when either;
• an interrupt occurs, or
• a skip instruction is executed.
The voltage drop detection circuit interrupt request flag cannot
be cleared to “0” at the state that the activated condition is
satisfied.
Each interrupt request flag is set when the activated condition is
satisfied even if the interrupt is disabled by the INTE flag or its
interrupt enable bit. Once set, the interrupt request flag retains set
until a clear condition is satisfied.
Accordingly, an interrupt occurs when the interrupt disable state
is released while the interrupt request flag is set.
If more than one interrupt request flag is set when the interrupt
disable state is released, the interrupt priority level is as follows
shown in Table 10.
Table 12 Interrupt enable bit function
Interrupt enable
bit
1
0
Occurrence of
interrupt
Enabled
Disabled
Skip instruction
Invalid
Valid
Rev.1.04 Aug 23, 2007 Page 23 of 146
REJ03B0188-0104