Information

Analog Shield: Introduction
To write multiple values to channels 0, 1, and 2 and have them update at the same:
unsigned int
data0 = 65535;
unsigned int
data1 = 256;
unsigned int
data2 = 0;
analog.write(data0, data1, data2, true);
Simultaneously updating methods are useful for higher speed applications where a small delay between channel
outputs will produce unwanted signals or timing issues. For example, to use the shield to drive the X-Y input of an
oscilloscope to draw a circle, a delay between writing the X and the Y channels produces a ghost ‘ellipse’ drawn
during the interim between the X and Y DAC updates.
This is a simple but powerful library to help the user get started. It is well documented to ease modification of the
library for any individual project. The power supply is entirely analog, and as such, needs no software to operate.
However, the ADC (part number DAC8564) and DAC (part number ADS8343) are both SPI devices. Their datasheets
are freely available on the manufacturer’s webpage.
Summary
Unlike the native analog input of the Arduino, the Analog Shield provides a 16 bit ADC, (as opposed to 10bits
provided by the Arduino UNO and the ChipKIT UNO32) offering greater precision (about 25dB) than the Arduino or
chipKIT. Additionally, the ADC works as a bipolar input, meaning that sense signals in the range of +/-5V can be
sensed without any additional hardware.
The onboard DAC provides a similar improvement in precision. The Analog Shield provides 16 bits of precision, and
offers as much as 25dB better signal-to-noise ratio when driving a sinusoidal output at low frequency.
The Analog Shield provides a compact integrated power supply with fixed and adjustable outputs to allow a variety
of analog circuits to be assembled with a minimum of wasted space and complexity.
Special thanks to Gregory Kovacs, Fernando Mujica, Clint Cole, and their respective teams at Stanford, TI, and
Digilent for supporting this project to its completion!
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
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