Q
What is the power-on configuration routine?
A
Every ADUC8xx product features a “power-on configuration routine” that runs
every time
you apply power to the chip or reset it. Basically, this is a small piece of
code that is executed prior
to the execution of your code. It is used to configure some of the on-chip
peripherals such as the
ADC and Flash/EE memory with factory optimized calibration and timing
parameters. Some of
these you can see (for example, default ADC offset and gain calibration
registers will be different
from one chip to the next) and others you can’t (for example, ADC linearity,
PTAT coefficients are
not visible to your code). For the Microcontroller devices that run off a 32kHz
crystal the power
on configuration will also wait for the part to ‘lock’ before it starts to run
user code.
The power-on configuration routine is stored in a hidden area of program ROM.
The address
where the routine begins is FF00 hex. Although the power-on configuration
routine is “mapped” to
addresses FF00 through FFFF hex, this does not interfere with external code
memory, which
shares these addresses. Up to 64K bytes of user code can be executed from an
external PROM
chip.