2013-09-25

High speed data acquisition with Raspberry Pi

Another common question is can I use the Raspberry Pi for data acquisition on its own?

The short answer is yes, but for digital signals only and only at relatively slow speeds. If you're serious about data acquisition, especially analog or mixed signal work, you'll need a peripheral device to plug into Raspberry Pi to provide the necessary I/O.

The original I/O peripheral and probably still the most widely used is Gert van Loo's Gertboard. It provides access to Pi’s GPIO and ATmega pins, a number of digital buffers, LEDs, button switches and high current output drives making it a very useful general purpose I/O board. However, for data acquisition (and generation) such as one might need to build an oscilloscope or waveform generator, its SPI connected D/A and A/D convertors are the important components.

For low speed data acquisition, up to 72kSps in the case of the Gertboard, it is possible to build a simple scope or waveform generator with Raspberry Pi. However like Gertboard, all the A/D boards we know of, as others have also reported, max out at sample rates well below 1MSps.

BitScope and Raspberry Pi

BitScopes like BS10 (shown here as part of a low cost electronic projects lab built around Raspberry Pi) are different from other peripherals for RPi.

BitScope can capture multiple analog and digital signals at very high sample rates (up to 40MSps in some cases) or it can stream continously at lower sample rates but in all cases sampling is done without loading the Raspberry Pi CPU or requiring a real-time operating system for low jitter sampling.

It's also more convenient because it connects and is powered via USB so it can work with a Raspberry Pi in a case. BitScope uses an industry standard IDC-26 Smart Port connector for analog and digital signal I/O, power and ground. It can even power and control small external circuits and is compatible with accessories like these dual channel active differential probes.

BitScope and Raspberry Pi make a great combination for many high speed data acquisition applications. See the related posts below for more details and stay tuned for some new announcements towards the end of the year.