Pi in the sky: Interview with Raspberry Pi co-inventor Eben Upton

Raspberry Pi has been an incredible success. Could you have foreseen that after just two years you would have shipped so many boards and achieved such industry recognition? What have the last couple of years been like? The last couple of years have been chaotic! We had spent the year prior to launch on the detailed design and attempting to settle down the costings, so actually for most of us involved in the Raspberry Pi design we've had an incredible journey these past three years. In the final stages before launch we also had a complete change of outlook. Our intention had been that we would manage building Raspberry Pi ourselves and, as a consequence, be somewhat limited in terms of production quantities. However, we then ended up licensing the design to RS, a decision that has proved to be fundamental to our success. Raspberry Pi Model B+ is about to launch. What new features will this revision have, and does this mean that the current Model B will no longer be available? Since launch we have seen Raspberry Pi being used in education, by electronics enthusiasts and by professional engineers for a breadth of applications that we never thought possible. The scope of applications in use today has certainly contributed to some of our on-going development planning. While the model A board is still available for those that don't need Ethernet connectivity, it is the B model that has been the most widely adopted and suits most applications. We are currently on revision two of the model B board design and have had a number of improvements on our mind that we are now incorporating into a third revision. These tweaks plus some other changes, brought about by how users are using Raspberry Pi, have led us to launch Model B+, our 3rd revision. The magnitude of some of these changes is such that we feel it goes beyond a simple design revision, hence why we have opted to identify the new design at a model level. One significant improvement is in power consumption. We've managed to achieve a 20 – 30% reduction in power consumption by moving from a linear power supply arrangement to a dual switching regulator. On the connectivity side, the number of USB ports had been a concern for a while. Two are good to attach a mouse and keyboard, but many users also have a Wi-Fi dongle and external hard disk so we decided to double the USB ports to four. To accommodate more control and I/O-based applications we've opted to bring out a larger percentage of the GPIO. The 26-pin connector is replaced with a 40-pin one. Some other incremental changes have been made to improve the audio quality with DSP-related fixes, and we have also decided to go with current market trends and opt for a micro SD card in place of the standard SD card package format, which is fast becoming obsolete. There are some changes to the form-factor of the board, so that will require a new case design. This time we're introducing our own case which, like the Pi, is designed and built in the UK and will be available for the launch. As regards making the Model B obsolete, customers should not be alarmed; we don't have plans to withdraw it any time soon. Having sold over three million Raspberry Pis since launch, the Model B has been good for us. Fear not; we aim to keep it in the market until sales dwindle in favour of newer models. What types of applications are currently using Raspberry Pi and what types of languages are being used in the development process? It's so difficult to choose any particular application; I've come across loads of different ideas. We've seen Raspberry Pi being used a lot for multimedia servers, something we didn't think would catch on in the way it has. Being used in place of consumer electronics products has been a big break for us. We believe that approximately half a million Raspberry Pis are used in this way. We've also seen a lot of commercial and industrial automation designs where Raspberry Pi is built into another system. In terms of the choice of development languages, Python has been extremely popular; in fact that's where the "Pi" comes from in Raspberry Pi. It is a really interesting language allowing you to develop for an embedded system using a very high level language. Scratch has also been popular, and together with Python has been adopted in many educational establishments. However, the benefit of using a Linux operating system gives developers the opportunity to use other languages such as Smalltalk, Ruby or JavaScript. Something that I think the Pi and boards like it are good at is blurring the lines between conventional software engineering and embedded engineering. The Broadcom BCM2835 brings an application processor class of compute device into the embedded domain, allowing you to do a much broader range of programming using a very wide range of tools. How far ahead are you planning with new developments, and how have customer implementations influenced your product development strategy? I mentioned earlier about how we've seen many boards incorporated into end systems. The interest for using Raspberry Pi in industrial designs has certainly led our decision to build a Compute module that provides the computing resources of a Raspberry Pi and gives end-system engineers more flexibility in terms of interfacing and connectivity. Constructed in a SODIMM package format and announced earlier in April 2014 we hope to have it into production shortly. We appreciate that some users might ask for a more powerful processor, but we are continuing to squeeze more and more performance out of what we have. For example, we've recently released an FFT library for the GPU. This is providing performance 10 to 15 times faster than the ARM CPU alone and is ideal for multimedia acceleration. So, for now, with the launch of the Model B+ and the Compute module we're going to be kept pretty busy!