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8-channel, 8-bit, 1 Msps SPI ADC Wing This is a simple Wing intended to extend the all-digital domain of Spartan 3E FPGA to analog. It is based on National Semiconductors ADC088S102 device, which is a 8 channel, 8-bit ADC capable of sampling rates of upto 1 Msps. It can be interfaced through the standard SPI/Microwire/QSPI serial interfaces between 8 to 16 MHz. It is intended to be used with the S3E Cocoon. This 8-bit ADC can also be relpaced with 10-bit ADC108S102 or 12-bit ADC128S102 versions that are pin and function compatible with same sampling rates. The standard board come with RC low pass filters for audio frequencies.
Applications
Specifications National Semiconductors ADC088S102, 1 Msps SAR A/D Converter with SPI Interface.
Pinout
Direction is from the perspective of the FPGA or microcontroller.
The clock used to read samples is also used for conversion process. Each serial frame is 16-bits long, containing both command entry and sample readout. Please refer to the device datasheet for more information.
Operational Limits and Precautions The IO voltage of the ADC is set to 3.3V The reference voltage of the ADC is set to 3.3V Do not exceed the analog input voltage above 3.3V Since data clock itself is used for conversion process, operating the Wing with software SPI is not recommended, as the clock speeds generated can be too slow for the internal track/hold capacitor to retain the sample reliably for the period of conversion process. A minimum frequency of 8 MHz is suggested.
Resources
FPGA support Since operating this Wing requires hardware support, a standard SPI peripheral core capable of 16-bit word can be used. Please refer to the ADC088S102 datasheet for the communication protocol. Alternatively, a peripheral core for register based ADC interface is being devloped for use with microcontroller cores.
Current StatusThe SPI ADC Wing PCB's are currently being built and tested. Look for this item to be available in the store in the next couple of weeks.
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