I am trying to connect an external ADC to Arduino UNO R3 Atmega328P. I am very new to this and not exactly sure how to choose the ADC and also how to connect it to the microcontroller.
I am attaching the KiCAD schematic where I have placed an ADC101C021 to connect to the microcontroller. Can anyone please help me understand how to know what ADC to use from reading the datasheet of the microcontroller?
To choose an external ADC, you must consider various factors. How many channels? What precision? What speed/rate of conversion?
Some external ADC will connect to the Arduino using the SPI bus, some via the I2C bus. SPI is faster but requires more pins. I2C is slower and needs fewer pins, and the slower speed may not be an issue depending on what ADC conversion speed/rate you need.
You seem to be using the SPI bus already in your project, for the waveform generator chip, so using SPI for the ADC chip also would be a good choice. They would share the clock and data pins.
You have not explained why you have not chosen to use the Arduino's built-in a ADC.