User`s guide

Elan Digital Systems Ltd. 23 AD125 USER’S GUIDE
3.5.3 SLEEP MODE
The AD125 can be put into a low power SLEEP mode. This
effectively shuts down the internal DC-DC converters, oscillator and
AtoD converter. The analogue part of the card will not function in
this mode. When enabling the card i.e. coming out of SLEEP mode,
allow at least 2 seconds for the power to stabilise before taking any
measurements.
The card powers up in SLEEP mode and enters SLEEP mode after a
hard or soft reset. Bit 3 of SETUP REG 1 controls the SLEEP state:
1→POWER ON, 0→GO TO SLEEP.
Important:
Note that after powering up the card and bringing the card out of
sleep, the RUN state should be set to active then back to inactive.
This allows internal clock generation to stabilise prior to taking any
ADC readings. Failure to do this can show as a “bad” first sample
from the ADC directly after power-up.
3.5.4 INTERRUPTS
The AD125 can generate interrupts if the HOST enables the PC-
Card IREQ signal to a PC interrupt channel. Using interrupts is a
convenient and efficient means of keeping track of what the card is
doing. Interrupts work differently depending on which mode the
card is in:
MODE CAUSE
BURST
WHEN CARD HALTS AFTER THE BUFFER HAS FILLED
FIFO
PROGRESS AS BUFFER FILLS. USE SETUP REG 2 BITS
0 AND 1 TO SELECT: 0-INTERRUPT ONLY WHEN
BUFFER FULL (NO USE FOR CONTINUOUS DATA
STREAMING), 1-INTERRUPT EVERY TIME THE
BUFFER IS HALF FULL, 2-INTERRUPT EVERY TIME
THE BUFFER IS QUARTER FULL, 3-INTERRUPT
EVERY CONVERSION.
SINGLE
IGNORE ANY INTERRUPTS THAT MAY OCCUR IN
THIS MODE