Rev.2.00 Oct 16, 2006 page 269 of 354
REJ09B0340-0200
M30245 Group
2. Multiple Interrupts
Previous
instruction
REIT
Interrupt sequence
Time
Interrupt request generated
Determination whether or not to
accept interrupt request
Previous
instruction
FSET I
Interrupt sequence
Next instruction
Interrupt request generated
Determination whether or not to
accept interrupt request
When changed by REIT instruction
When changed by FCLR, FSET, POPC, or LDC instruction
(If I flag is changed from 0 to 1 by REIT instruction)
(If I flag is changed from 0 to 1 by FSET instruction)
Time
Figure 2.15.3. The timing of reflecting the change in the I flag to the interrupt
(2) Interrupt Enable Flag (I flag)
The interrupt enable flag (I flag) controls the enabling and disabling of maskable interrupts. Setting
this flag to “1” enables all maskable interrupts; setting it to “0” disables all maskable interrupts. This
flag is set to “0” after reset.
The content is changed when the I flag is changed causes the acceptance of the interrupt request in
the following timing:
• When changing the I flag using the REIT instruction, the acceptance of the interrupt takes
effect as the REIT instruction is executed.
• When changing the I flag using one of the FCLR, FSET, POPC, and LDC instructions, the
acceptance of the interrupt is effective as the next instruction is executed.
(3) Interrupt Request Bit
The interrupt request bit is set to "1" by hardware when an interrupt is requested. After the interrupt is
accepted and jumps to the corresponding interrupt vector, the request bit is set to "0" by hardware.
The interrupt request bit can also be set to "0" by software. (Do not set this bit to "1").
(4) Interrupt Priority Level Select Bit and Processor Interrupt Priority Level (IPL)
Set the interrupt priority level using the interrupt priority level select bit, which is one of the component
bits of the interrupt control register. When an interrupt request occurs, the interrupt priority level is
compared with the IPL. The interrupt is enabled only when the priority level of the interrupt is higher
than the IPL. Therefore, setting the interrupt priority level to “0” disables the interrupt.
Table 2.15.1 shows the settings of interrupt priority levels and Table 2.15.2 shows the interrupt levels
enabled, according to the contents of the IPL.
The following are conditions under which an interrupt is accepted:
· interrupt enable flag (I flag) = 1
· interrupt request bit = 1
· interrupt priority level > IPL
Содержание M16C FAMILY
Страница 12: ...Chapter 1 Hardware...
Страница 13: ...See M30245 group datasheet...
Страница 14: ...Chapter 2 Peripheral Functions Usage...
Страница 303: ...THIS PAGE IS BLANK FOR REASONS OF LAYOUT...
Страница 304: ...Chapter 3 Examples of Peripheral Functions Applications...
Страница 340: ...Chapter 4 External Buses...
Страница 361: ...THIS PAGE IS BLANK FOR REASONS OF LAYOUT...
Страница 362: ...Chapter 5 Standard Characteristics...
Страница 369: ...1753 Shimonumabe Nakahara ku Kawasaki shi Kanagawa 211 8668 Japan M30245 Group REJ09B0340 0200 User s Manual...