This is a breakout board for the Microchip MCP3008 Analog-to-Digital Converter chip featured on the I2C and SPI Education Shield and is compatible with all the associated Rheingold Heavy tutorials.
When you’ve run out of analog inputs on your microcontroller, the MCP3008 is ready to pick up where those pins left off, adding an addition 8 channels of 8-bit sampling. The chip allows measurement against either a 5V or a 3V3 reference, so they are both included and available to select using a jumper. (If you’re planning on using a microcontroller connected to a USB port for power, remember that you won’t get a true 5V reference, but something closer to 4.88 due to drop out.)
Having 8 extra channels is cool with fixed references, but the MCP3008 also allows you to gang two channels together to act as a psuedo-differential input pair. That means that you can compare one channel’s voltage level against the paired channel, even though the paired channel may be fluctuating. That allows you to filter some noise out of your ADC values if necessary, or compare and contrast two signals against each other.
The MCP7940 communicates over SPI making it very fast and male header pins are used to deliver the SPI and voltage pins. On the other side of the board, the eight input channels as well as a common Analog Ground are accessed through a female header.
Board pictured is a prototype – final board may include minor changes.