Renesas SH7781 - Manual (Page 293)

10. Interrupt Controller (INTC)
Rev.1.00 Jan. 10, 2008 Page 263 of 1658
REJ09B0261-0100
Section 10 Interrupt Controller (INTC)
The interrupt controller (INTC) determines the priority of interrupt sources and controls the flow
of interrupt requests to the CPU (SH-4A). The INTC has registers for setting the priority of each
of the interrupts and processing of interrupt requests follows the priority order set in these registers
by the user.
10.1 Features
The INTC has the following features:
• Fifteen levels of external interrupt priority can be set
By setting the interrupt priority registers, the priorities of external interrupts can be selected
from 15 levels for individual pins.
• NMI noise canceller function
An NMI input-level bit indicates the NMI pin state. The bit can be read within the interrupt
exception handling routine to confirm the pin state and thus achieve a form of noise
cancellation.
• NMI request masking when the block bit (BL) in the status register (SR) is set to 1
Masking or non-masking of NMI requests when the BL bit in SR is set to 1 can be selected.
• Automatically updates the IMASK bit in SR according to the accepted interrupt level
• Thirty priority levels for interrupts from on-chip peripheral modules
By setting the ten interrupt priority registers for the on-chip peripheral module interrupts, any
of 30 priority levels can be assigned to the individual requesting sources.
• User-mode interrupt disabling function
An interrupt mask level in the user interrupt mask level register (USERIMASK) can be
specified to disable interrupts which do not have higher priority than the specified mask level.
This setting can be made in user mode.
• Holding mode of the level-sense IRQ and IRL interrupt sources (ICR0.LVLMODE)
For the IRQ and IRL interrupts when the level sensing is set, the following two modes are
available:
(a) A mode in which the source of interrupt is temporarily held inside of the INTC even if the
input level of the external pin is not retained.
(b) A mode in which the source of interrupt is not held inside of the INTC.
(c) The initial value of ICR0.LVLMODE is 0; however, it is recommended to set
ICR0.LVLMODE to 1 by setting the interrupt control register 0 (ICR0) by the initialization
routine.