
2.9 External Interrupts
170
Chapter 2: Hardware
(3) ELVR (Request Level Setting Register)
s Register Configuration
s Register Description
The ELVR register is used to select the mode of request detection. 2 bits are assigned to each pin, and
are set in combination as shown below. For level interrupt signals, the signal can be set again even by
clearing the register setting if the input is at active level.
Table 2.9.1 ELVR Bit Settings
2.9.4 Operating Description
(1) External Interrupt Operations
When external interrupt requests are set, this resource will generate an interrupt request signal to the
interrupt controller whenever an interrupt designated in the ELVR register is received at the
corresponding input pin. Interrupts generated simultaneously are assigned priority values by the
interrupt controller. If an interrupt from this resource has the currently highest priority, the interrupt
controller will generate an interrupt request to the F2MC-16L CPU, which will compare the interrupt
with the ILM bit in its own internal CCR register. If the interrupt has a higher level than the ILM bit, the
CPU will then stop the currently executing instruction, and start the hardware interrupt processing
microprogram.
LBx
LAx
Operation
0
Interrupt request at L level signal
0
1
Interrupt request at H level signal
1
0
Interrupt request at rising edge
1
Interrupt request at falling edge
LB3
LA3
LB2
LA2
LB1
LA1
LB0
LA0
Bit no.
Read/write
(R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W)
Initial value
(0)
Address : 00002AH
7
6
5
4
3
2
1
0
ELVR
LB7
LA7
LB6
LA6
LB5
LA5
LB4
LA4
Bit no.
Read/write
(R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W)
Initial value
(0)
Interrupt request level setting register - high
Address : 00002BH
7
6
5
4
3
2
1
0
Interrupt request level setting register - low
External interrupt
Other interrupt requests
Interrupt controller
F2MC-16L CPU
ELVR
EIRR
ENIR
ICR yy
ICR xx
CMP
Source
IL
ILM
CMP
INTA