ADUC7023 Analog Devices, ADUC7023 Datasheet - Page 20

• Manufacturer Part Number: ADUC7023
• Description: Precision Analog Microcontroller, 12-Bit Analog I/O, ARM7TDMI MCU
• Manufacturer: Analog Devices

Specifications of ADUC7023

• Mcu Core: ARM7 TDMI
• Mcu Speed (mips): 40
• Sram (bytes): 8192Bytes
• Gpio Pins: 20
• Adc # Channels: 12
• Other: PWM

ADuC7023
More information relative to the model of the programmer and
the ARM7TDMI core architecture can be found in ARM7TDMI
technical and ARM architecture manuals available directly from
ARM Ltd.
INTERRUPT LATENCY
The worst-case latency for a fast interrupt request (FIQ)
consists of the following: the longest time the request can take
to pass through the synchronizer, the time for the longest
instruction to complete (the longest instruction is an LDM) that
loads all the registers including the PC, and the time for the
data abort and FIQ entry.
At the end of this time, the ARM7TDMI executes the instruc-
tion at 0x1C (FIQ interrupt vector address). The maximum
total time is 50 processor cycles, which is just under 1.2 μs in a
system using a continuous 41.78 MHz processor clock.
Rev. B | Page 20 of 96
The maximum interrupt request (IRQ) latency calculation is
similar but must allow for the fact that FIQ has higher priority
and could delay entry into the IRQ handling routine for an
arbitrary length of time. This time can be reduced to 42 cycles if
the LDM command is not used. Some compilers have an option
to compile without using this command. Another option is to run
the part in thumb mode where the time is reduced to 22 cycles.
The minimum latency for FIQ or IRQ interrupts is a total of
five cycles, which consist of the shortest time the request can
take through the synchronizer, plus the time to enter the
exception mode.
The ARM7TDMI always runs in ARM (32-bit) mode when in
privileged modes, for example, when executing interrupt
service routines.