How can I acquire analog signals with Raspberry Pi?

What sort of analogue signal ?

You need to define (at least)  amplitude, frequency range (if not DC), resolution, accuracy, number of samples per second.

There are thousands of ways you might measure a signal so you need to narrow things down a bit before anyone can help.

MK

Here are the details :

+/- 10 V range

Frequency range is <100 Hz

No. of samples is >10 Hz

Above are rough numbers. Im looking for something near to these numbers.Its basically to acquire signals from say a pressure sensor.

Hope I could bring in some clarity.

Your frequency range and sample rate are not compatible - generally you should expect to sample at at least 5x the maximum frequency for instrumentation systems. If your pressure sensor signal really has compenents above the sampling frequency then you should filter them out before the ADC.

You haven't quoted anything for resolution or accuracy.

There are loads of ADC add ons for the PI, look at Gertboard or ADC Pi - 8 Channel Analogue to Digital converter for the Raspberry Pi computer boards ADC PIV2

but there are many others - try Google.

Either of these boards will need signal conditioning  to accept a +/- 10V input.

Does your pressure senot really ouput +/- 10V ?

MK

this webinar has also just been presented and deals with the exact topic and more

it should be posted soon to view http://www.element14.com/community/events/4026

Peter

Hi Michael,

              Thanks for answer. Im sorry - I have given the answer from the perspective of what Im feeding to my PC based DAQ using a PC based hardware and the signal conditioner. So I was actually giving details of the signal from the conditioning and the 10 Hz I mentioned was the datalog rate on the PC. Apologizes for the confusion.

Now, let me try to give you a clearer picture:

So, what I wish to make is to replace the PC based hardware with a system based on Raspberry Pi - a 4 channel at least 12 bit (preferably more) resolution. Sampling rate of at least 10kSamples/ sec per channel(so that I have a range available, in case I need for some dynamic parameter measurements).

Even if something in the range +/- 5V is available I can program my signal conditioner accordingly.

Let me know, if  could explain. In case Im still missing something, please let me know.

Thanks & Regards

Srin

NI have device, USB6009 which claims to have  a Raspberry Pi driver - I suggest you check very carefully that it will do what you want before buying one.

If you are into building things you could make something much, much cheaper based on a microcontroller dev board like one of the ST Discovery boards.

MK

I want to build this.

In that case, are you able to solder 0.5mm lead pitch chips to a PCB you design yourself or would you rather start with a dev. board and either make a much simpler board or just use ready made parts.

MK

I would love to get my hands dirty. But don't mind skipping over to dev. boards, if it does offer significant benefit.

Most obvious ways as probably already stated here are:

Gertboard from E14

A/D such as the MCP3008 on the SPI bus

Add an Arduino to the USB and use it's Analog Inputs

Use one of those  instrumentation logging devices that connect to USB as long as you have Linux support you should be good!