How can I get the arduino to read a signal (signal generator, sine or whatever) and output the same signal from one of the DAC?
I'm sorry, I don't know how to code it; I am going through tutorials and reading to properly learn it, but I want to do this one thing now.
The DAC output can only go from 0.55V to 2.75V. If your desired output signal is in this range, then you can do it directly.
Unfortunately almost any signal you can think of will go outside this range. You will need an opamp to convert the 0.55-2.75 range into the range you need. If you're just mirroring the signal then use the opamp without the Due.
That kind of renders the DAC outputs useless... I was trying to use them for a feedback system. But then the PWM outputs can't go below zero... which also limits their usefulness. I could always use op-amps to put a negative offset on the analog or PWM signal and get a zero crossing, right? Is there another trick I could use?
I only wanted to output the same input signal to connect to a network analyzer and see the frequency response of the arduino input->output loop. Curiosity.
Well, you're always going to need some kind of amplifier to get a usable signal out of any DAC. If you buy an off-the-shelf DAC chip, it's unlikely to have the power rating required to drive a speaker or industrial actuator, so you will always use an amplifier.
It does seem like an odd range. I've not come across anything else quite as limited before. These days, 85% of any 'analog' task you want to do is best accomplished with PWM so true analog is getting rarer.