Connecting the output from a function generator through a BNC cable to the input pins of a pcf8591

I am trying to work with the signals generated by a function generator using Raspberry Pi. Since Raspberry Pi does not have an inbuilt ADC, I used pcf8591. Now, I do not know how to feed the signal generated by the function generator into the input pins of pcf8591. Please help.

John... the main thing to bear in mind when doing this is that the inputs to the PCF 8591 can only go from ground to supply positive - if using the same power as the Raspberry PI thats 0 to 5 volts.  If your function generator puts out an AC signal you will have to do some signal processing to centre it around 2.5 volts.  Also you will have to make sure that the input signal does not go above these limits - ie 0 to 5 volts or +/- 2.5V if you're centring it.Adafruit have a nice write-up on using ADCs with the RPi here.  But very much similar limits as above will apply to these ADCs as well I think.

John
If you have never worked with an ADC before, I would suggest you start with DC voltages to get your software in a state that  you are confident that the ADC and your system are working correctly. David’s words of caution on input voltage limits are well founded so take heed!A modified approach could be to rectify your input signal  (either half or full wave)  to stop the input signal going negative. It make the software easier to write, although you have to take into account the diode drops.Oh, and a thought occurs to me- if the name Nyquist does not mean anything to you, you need to read up about sampling AC waveforms (or any other waveform that changes over time).

If the function generator has an offset control, you could use that to shift the AC output to swing within the gronund-and supply limits of the ADC.If you are looking only at AC signals, you could AC-couple the signal to the ADC input: Connect a 10,000-ohm resistor from supply to ADC input, and another 10,000-ohm resistor from ADC input to ground. This will bias the ADC input at half the supply voltage. Check the ADC input's input-current spec in the datasheet, to make sure that the input current will not shift the DC operating point excessively. Then connect a capacitor from the function-generator output to the ADC input. Choose enough capacitance so that the capacitor's reactance is small compared to 5000 ohms.