Book Analog Interfacing to Embedded Microprocessors
reference to a voltage comparator to simulating a sine wave. I used a DAC in
an unusual application years ago in a piece of military gear that was replac-
ing older equipment. The original equipment had an analog signal that
controlled a horizontal situation indicator (a meter) in an aircraft. We were
performing these functions in software, so the DAC, under software control,
generated the voltage to drive the analog meter.
The Analog Devices AD7801 is a typical 8-bit, voltage-output DAC. The
microprocessor interface consists of 8 data bits, a -WR (write) signal and a
-CS (chip select) signal. Data is written to the device by toggling -WR while
-CS is low. The AD7801 can operate at voltages from 2.7 to 5.5 volts. The part
also has a -CLR pin that, when low, loads the DAC with all 0s.
154 Analog Interfacing to Embedded Microprocessors
Figure 6.14
Multiple series LEDs.
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