08 May 2012
Fruits of his labours: Interview with Pete Lomas, Raspberry Pi hardware designer
The man who designed the hardware for the Raspberry Pi tells Chris Shaw what the device means to him.
Readers of a certain age will remember the BBC Micro and its impact on the British education system throughout the 1980s. Developed by Acorn as an educational tool and launched at the end of 1981, it introduced schoolchildren to the unprecedented concept of freely available computing.
Thirty years on, the Raspberry Pi has entered the arena, targeting a similar age group. The credit card sized computer, which costs little more than £20, is designed to engage with a new generation of budding engineers and computer experts.
Pete Lomas, director of systems engineering at electronic design consultancy Norcott Technologies, designed the Raspberry Pi's hardware. He said the idea arose from a conversation with Professor Alan Mycroft from the University of Cambridge's Computer Laboratory. The discussion turned to the need for students to be taught about 'real computing'. Lomas' concerns were heightened by his background in computer engineering, in which youngsters showed a similar lack of interest in electronics design.
"A few weeks later, I met with the team in Cambridge that eventually became the Trustees of the foundation and offered to help to bring this project to fruition," said Lomas. "I clearly saw Raspberry Pi as a way of giving potentially large numbers of students access to a low cost open computing platform and – at the same time – we could embrace aspects of experimentation at the hardware level."
The early concepts were developed in 2006, based on an Atmel ATmega644 mcu. Then, the main design criterion was its ability to run Python as a teaching language on top of a version of Linux. From a hardware perspective, it needed a display, mouse, keyboard, simple storage media and a general purpose I/O port for the electronics and interfacing.
"Although we had grown up with the BBC Micro, it was clear that whatever we came up with would need to align with today's expectations; 640 x 480 graphics were not going to cut it," Lomas recalled. "Equally, in some teaching environments, we could see that good quality graphics and multimedia capability would be highly desirable."
During the design process, there were a number of disagreements, not least the debate on internet connectivity. According to Lomas, this became quite heated. "We could all see the value, but could we sustain the cost?," he recalled. "In the early days, we had some abortive attempts at getting a design together, but always seemed to need too much peripheral support and this pushed up the cost. The SMSC LAN9512 chip came to our rescue, with two USB ports and a 10/100 Ethernet port."
Another breakthrough came with the Broadcom BCM2835 SoC. "This seemed like a brilliant fit," said Lomas. "ARM core, 1080p HDMI, GPU, USB and bootable from a SD card. Nothing else came close to its feature set and price performance. We also gained the important benefit of a composite video and stereo sound output for use in environments where HDMI displays are not readily available."
Broadcom's design engineers built a proof of concept and passed it to Lomas for cost and size reduction. "My target was a credit card sized, simple pcb with a minimum component count. We removed everything we felt was not essential and pared down the I/O – nice, but non essential, functionality could be added via USB or the GPIO. We ended up with a three chip solution, plus power supplies and connectors on a credit card sized conventional six layer board."
To Lomas' relief, Raspberry Pi appears to have captured the public's imagination. Within a week of release, more than 30,000 consumers downloaded the operating system software – amassing more than 30Tbyte of file transfers. Lomas describes the public's initial feedback as 'phenomenal'. "It's way beyond what I expected," he said. "Many people wish Raspberry Pi had more memory, more onboard peripherals and a faster processor, but they also see the value in the price. In the main, everyone has been very supportive."
Lomas hopes the device will play some part in addressing the decline in core computing skills and provide an opportunity for youngsters to unlock their creativity. "An open system like Raspberry Pi will provide a vehicle to do that," he said. "At the electronics hardware level, we are looking at breakout modules to provide connectivity to real world interfaces. For me, engineering is all about taking an idea and turning it into reality. Giving youngsters their first taste of creating something from just an idea is critical. I hope that the sense of achievement that comes with it will have them hooked."
Lomas' enthusiasm continues beyond the excitement of seeing his labour of love through to the end. He is optimistic that Raspberry Pi could play a part in inspiring young people to consider design engineering as a profession. "It is imperative that we promote all forms of creativity and innovation but, in recent years, I feel that science and technology in education has not had the support it needs," he said. "We hope that, through the Foundation, we can continue to raise awareness, lobby for changes to the curriculum and provide the tools and accessibility through the Raspberry Pi. We also recognise how difficult a task this will be and that we are only one small part of the solution."
Small steps, but Lomas believes this is just the beginning. "Once we get into an educational deployment, I'm sure we will find things that we could and should have done better," he said. "This will certainly lead to a new version of Raspberry Pi in the future. We will also listen to our community of users and developers to try and incorporate their ideas and comments. For the moment, our focus is very much on what we have today."
Pete Lomas is cofounder and director of systems engineering for Norcott Technologies, responsible for product and systems engineering development. Prior to founding Norcott, he was director of engineering for electronic design consultancy Mosaic Technology.
Lomas has also been a lecturer in computer engineering and cad/cam systems, a freelance engineering consultant and development manager for Kemitron.
During his 30 year career, he has developed more than 100 electronic products containing some 280 pcbs.