AT91M40800
8.4
System Peripherals
8.4.1
PS: Power-saving
The Power-saving feature optimizes power consumption, enabling the software to stop the
ARM7TDMI clock (idle mode), restarting it when the module receives an interrupt (or reset). It
also enables on-chip peripheral clocks to be enabled and disabled individually, matching power
consumption and application need.
8.4.2
AIC: Advanced Interrupt Controller
The Advanced Interrupt Controller has an 8-level priority, individually maskable, vectored inter-
rupt controller, and drives the NIRQ and NFIQ pins of the ARM7TDMI from:
• The external fast interrupt line (FIQ)
• The three external interrupt request lines (IRQ0 - IRQ2)
• The interrupt signals from the on-chip peripherals.
The AIC is largely programmable offering maximum flexibility, and its vectoring features reduce
the real-time overhead in handling interrupts.
The AIC also features a spurious vector, which reduces spurious interrupt handling to a mini-
mum, and a protect mode that facilitates the debug capabilities.
8.4.3
8.4.4
8.4.5
PIO: Parallel I/O Controller
The AT91M40800 microcontroller has 32 programmable I/O lines. Six pins are dedicated as
general-purpose I/O pins. Other I/O lines are multiplexed with an external signal of a peripheral
to optimize the use of available package pins. The PIO controller enables generation of an inter-
rupt on input change and insertion of a simple input glitch filter on any of the PIO pins.
WD: Watchdog
The Watchdog is built around a 16-bit counter and is used to prevent system lock-up if the soft-
ware becomes trapped in a deadlock. It can generate an internal reset or interrupt, or assert an
active level on the dedicated pin NWDOVF. All programming registers are password-protected
to prevent unintentional programming.
SF: Special Function
The AT91M40800 microcontroller provides registers that implement the following special
functions.
• Chip identification
• RESET status
• Protect mode
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1348FS–ATARM–13-Apr-06
ATMEL [ ATMEL ]
