July saw the launch of Raspberry Pi 4, the board that became the development standard for IoT. However, It is easy to overlook another event in the Pi calendar. This July marks the fifth anniversary of Raspberry Pi model B+. We are familiar with its key features now, but at the time it was a massive change to a 40-pin expansion connector, no composite video socket, four mounting holes, and carefully designed interface connectors.
The latest Pi 4 has two dual mini-HDMI connectors and reversed Ethernet and USB positions. This design marks the first significant deviation from the standard set by the model B+ and its successors. It is good to take a look at the success of the form factor and its broader impact.
Form Factor Evolution:
The first Raspberry Pi, launched in 2012, was not the polished production of a slick electronics company. However, it was a creation from a group of electronics and computing professionals who built the board in the hope that they can teach some kids to code. Their production blogs in 2011 was a fascinating course of the challenges they faced in preparing a composite board for production. A Chinese assembly company creating the first samples and then did a heroic SMD rework task on that very first batch.
It’s fair to say that merely getting it to the point at which we could buy a Pi was the stellar achievement. The board layout itself owed more to necessity than a path towards a future line of successors. The credit-card size was perfect. It had no mounting holes, for example, and the position of various connectors at all points of the compass with the composite video and USB sockets protruding over the board edge.
Something better was needed, and the B+ in 2014 delivered what was mainly the same hardware as the original with those aforementioned mounting holes, neat arrangement of connectors, and a new 40-pin header. This form factor became the basis of the new HAT specification for all expansion boards.
Raspberry Pi Standard
The success of the Pi had not gone unnoticed by potential competitors, and within its first year, there were a host of other boards called Pi killers. Between 2012 and 2014 there boards like Cubieboard, Odroid-W came in different form factors like Raspberry Pi. Hummingbird had the same form factor as Pi in 2014.
The launch of the B+ changed all that, as the Pi now had a well-thought-out form factor. Successors to the Model B+ would follow the same format, which gave the after-market of add-on manufacturers the confidence they needed to support it. Subsequently, many other Single board computers (SBC) came to market like Orange Pi, Nano Pi, Banana Pi, Odroid, RockPi, Asus, Libre Computer, and Zberry.
The good and the bad of Raspberry Pi Design:
The success of all these machines with the same form factor and the vast range of HATs to go with them would indicate that the Raspberry Pi designers got something right five years ago. Physically the dimensions of the board and choice of the 40-pin connector at one edge avoided the pitfall of all other previous designs including Arduino. The original Raspberry Pi B+ had a bare processor. However, most of the more recent boards have to find space for a heatsink and possibly even a fan due to heat generation.
The Raspberry Pi 4 has followed the same HAT form factor as the B+. However, it is the first of the line to make significant changes to the rest of the formula. It has been typical for clones to reverse the positions of USB and Ethernet sockets and USB-C for power is an obvious progression. Pi 4 makes a more controversial choice in its replacement of the single full-size HDMI socket with a pair of micro-HDMI receptacles. RaspberryPi Zero has always had a mini HDMI socket it has ever brought with it the annoyance of having to find an adapter. The attraction of the Pi from day one was that it could be plugged directly into a domestic television. One loses this benefit with Raspberry Pi 4. Pi 4 is sure to trigger a bunch of new case designs.
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