I am trying my first SPI interface from the UNO to the MCP3301 13-bit ADC. I think I've got it straight, in terms of software, but after looking at some of the MCP3301 test circuits on the data sheet, it appears there is a pullup resistor on the data-out line, although that is not mentioned in the text. Has anyone played with this? Other than that the circuit appears stone simple. Anyone have any experience with this chip?
The data out pin goes high-impedance when SPI isn't being accessed - a pull-up could be used if the rest of the
circuit needs it to be defined (or if its a micro-power circuit and you want to avoid losses due to floating
inputs (floating inputs can cause input circuitry to shoot-through). I wouldn't worry about it unless using
sleep-mode in the Arduino.