Eben Upton interview on Raspberry Pi Compute Module
Electronics Weekly editor Richard Wilson interviews Eben Upton, founder of the Raspberry Pi Foundation, about the the design changes in the new Raspberry Pi Compute Module.
Q: What prompted you to develop this new compute module and why have you changed the form factor?
Eben Upton: Yes, this has been a busy year for us. The Compute Module was a concept that James Adams, Director of Hardware Engineering, came up with. We’ve seen lots of different applications for Raspberry Pi over the past couple of years, but something that did take us a little bit by surprise was how some equipment designers were incorporating a complete Raspberry Pi into their end system. Typically these are systems that are for low to mid volume industrial or commercial equipment.
In many cases developers then add an additional IO board to cater for additional connectivity, particularly for something Raspberry Pi might not have already. This got James thinking about how we could provide all the computing resources of the Pi in a compact format but leave the IO to the end system manufacturer or to a third party supplier. For example, we often get requests for a Raspberry Pi with Power-over-Ethernet (PoE) but the number does not warrant us putting that into the base design.
James came up with the idea for the Compute Module and we feel that this will become essentially a component for designers to incorporate into their own system. So the Compute Module allows us to address the professional industrial market in a way that we hadn’t even considered when we first embarked on the initial Raspberry Pi development.
The module consists of the same Broadcom BCM2835 SoC, 512Mbyte of RAM and a 4Gbyte eMMC flash all packaged on to a small 67.6 x 30 mm board that fits into a standard DDR2 SODIMM socket.
Q: The development approach to using the module would appear to be different from that of the typical Raspberry Pi board. How do you see that working?
Eben Upton: Well, there are a few changes but essentially the software development will remain the same. To ease the development of an end system we will be supplying a development board for the Compute Module. This development board will bring out all the IO connectivity available and also provide all the other parts of a standard Raspberry Pi such as the HDMI socket, USB connectors and pin headers.
There is a SODIMM socket that the Compute Module goes into and effectively forms a complete Raspberry Pi, albeit in two parts. The development board design is open source and we believe that it will become a prototyping platform for developers.
We don’t believe that anybody will incorporate this board into their system; it’s both more expensive and larger than a Raspberry Pi. Our belief is that developers might first prove their software design on a standard Raspberry Pi, then migrate to a Compute Module and development board set-up as a way of bringing out required IO to prototype their own interface board.
Once their design has been validated they will move to their own interface board that will host the Compute Module. We’re hoping that developers will have a very smooth experience without too many hiccups, from prototyping on the Pi through to shipping commercial product in volume.
Q: The success of the Raspberry Pi has spawned a market for third party extension boards, modules and accessories. Do you see that continuing with the launch of the Compute Module?
Eben Upton: We believe this is going to be an exciting opportunity. Firstly, and we’re getting a hint about this already from our early access developers, it will allow the creation of other Raspberry Pi-based designs, providing all kinds of connectivity with the Compute Module at its heart. We might see as many as 10 variants of Raspberry Pi in this way over the next year or so, in many new applications.
Secondly, as I mentioned earlier on the PoE example, we will hopefully kickstart third parties into creating a whole new line-up of interface boards and host boards for the Compute Module.
The development board will help in many initial designs but we never anticipated that it would be a popular product and be incorporated into complete designs. So this leaves lots of opportunities for others to pick up on. Again, we’ve already got some insight to potential board designs.