is there a good chip for extra ADC's?

Hey everyone,

I am building a line follower and I was wondering how to get more ADC pins on my arduino based robot than the standard six that come with the arduino. Idealy i need a total of 8, but in general, I am wondering if there is a "goto" chip that people commonly use for extra adc's and how it works and how fast it is compared to the standard arduino pins etc.

Thanks -Epic

Some options:

  1. Use an Arduino Mega, which has 16 analog input pins.

  2. Stick with the single ADC in your Arduino (which I assume is a Uno or other atmega328-based one), but expand the number of inputs using an external analog multiplexer such as the CD4051B (which gives you 7 additional inputs using 3 output pins) or CD4052B (which gives you 6 additional inputs using 2 output pins).

  3. If you need higher ADC conversion speed or higher resolution and not just more inputs, go for an external ADC with SPI or I2C interface. There are lots to choose from, and I can't recommend one without knowing what speed and resolution you want.

I've been using MCP3208, 12-bit, 8-channel ADC, SPI interface, works very nice. Connect Vref to +5V, with a 0.1uF cap to Gnd. http://search.digikey.com/us/en/products/MCP3208-CI%2FP/MCP3208-CI%2FP-ND/305928 In my application I sample an input every 5ms (so all 8 every 40mS) and send the sampled input over RS232 to 1 of 8 DACs that then recreate the 0/5V input. Will certainly go faster.

The Teensy has 12 analog pins on a USB-capable chip, assembled board for $16.