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Besides 14 pins for digitial GPIO, there are also 8 analog inputs on the Arduino Uno Expansion
Header. Consequently, we use ADC LTC2308 from Linear Technology on the board for possible
future analog-to-digital applications.
The LTC2308 is a low noise, 500ksps, 8-channel, 12-bit ADC with an SPI/MICROWIRE
compatible serial interface. This ADC includes an internal reference and a fully differential
sample-and-hold circuit to reduce common mode noise. The internal conversion clock allows the
external serial output data clock (SCK) to operate at any frequency up to 40MHz.
The LTC2308 is controlled via a serial SPI bus interface, which is connected to pins on the Cyclone
V GX FPGA. A schematic diagram of the ADC circuitry is shown in
. Detailed
information for using the LTC2308 is available in its datasheet, which can be found on the
manufacturer’s website, or under the Datasheets\ADC folder on the Kit System CD
l
ists the ADC SPI Interface pin assignments, signal names relative to the Cyclone V GX
device.
Figure 3-28 Arduino Analog input (ADC) Pin Arrangement and Connections
