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AD1200 Reference
selecting the digital i/o ports instead of the ADC as the
recipient of the interrupt or DMA data, at the same time,
the pacer clock source and divisor is selected, determining
the frequency of the pacer clock strobes.
iii)
A write to the ADGCR register or an negative edge on the
external trigger input starts the pacer clock as selected by
the ADCSR Mode bits.
iv)
DIG strobes will be automatically generated by the pacer
clock at the chosen rate, based on the 600kHz oscillator or
external clock input as selected by the ADCSR Mode bits.
The pacer clock strobe causes an interrupt or DMA cycle
which then updates the DIGIN or DIGOUT registers ready
for the next pacer clock strobe.
v)
When the required number of conversion has taken place
the pacer clock is stopped either by the interrupt service
routine or by the DMA TC, terminal count signal.
The clock may also stopped by a write to the ADCSR.
Screw Terminal Board.
____________________ _
The easiest and tidiest way to connect your i/o card to
your rig is via the Analogue Screw Terminal Board, ATB.
The Screw Terminal Board converts from 50 IDC ribbon
to screw terminals. The screw terminals can take wire up to
2.5mm, 0.1 inch diameter. The 50IDC entry is a latching
connector to ensure hold fast connections.
Power taken from the PC via at 12Volts is fed through
power on indicator LEDs and decoupling capacitors.
There is provision for an optional 4-20mA conversion form
both DAC analogue output signals.
There is provision for an optional 4-20mA conversion to
the analogue voltage input channels of the A/D converter.
Each screw terminal, is clearly identified by IDC pin
number, and AD1200 signal name.
The analogue and digital grounds are kept separate.
The digital i/o lines can also take an optional LED to show
signal logic state.
A handy cable grip clamps the wires to ensure a robust,
Page 22
Introduction
Chapter 1
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