How to use a DAC0808 with the arduino

Look for a single rail dac, they exist.

racemaniac: What exactly is the simplest DAC you can come by that's easy to use? .... my purpose.

simplest -- see R-2R resistor ladder network (digital to analog conversion, or DAC)

http://en.wikipedia.org/wiki/Resistor_ladder

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/dac.html http://www.tek.com/blog/tutorial-digital-analog-conversion-%E2%80%93-r-2r-dac http://www.irctt.com/pdf/LADDERNETWORKS.pdf

Anyway, you only get something for nothing on "Instructables".

I would recommend NOT using a DAC0808 if you can avoid it, for 3 reasons:

  1. Parallel input uses a lot of pins. An SPI DAC will only use 3 (Clock, Data, and Chip select).

  2. It requires a negative voltage to bias the output circuitry. My DAC0808 datasheet says it requires a minimum of -4.5 V on Vee. Grounding it won’t cut it.

  3. It is a current output DAC. Measuring the open-circuit voltage on pin 4 will tell you nothing. You need something to convert the current into a voltage. A resistor works, but gives you negative voltages because the device sinks current (ie, pulls it in). The op-amp transconductance amplifier in the example circuit will give you positive voltages.

Use an SPI DAC from Microchip (http://www.mouser.com/Semiconductors/Integrated-Circuits-ICs/Data-Converter-ICs/Digital-to-Analog-Converters-DAC/_/N-6j74u?P=1z0z63x&Ns=Pricing|0). They’re cheap, can have up to 12 bits resolution, come in single and dual packages, and have a direct voltage output instead of a current output. The only downside is that they’re slower than parallel DACs (Not a concern at Arduino speeds), and harder to use since you can’t just hook up some switches, you need a microcontroller that can shift out the data.