Model B+ Raspberry Pi Mounting Issues
14th July 2014
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With the introduction today of the new Model B+ it is important to take note of the physical differences as well as the functional changes that have been made.
Purchase from here
The physical differences mean that some add-on boards and most (all?) existing cases cannot be used with the new Model B+
To see why this may be, let’s enumerate some of the various physical changes
- Both boards are the same nominal size at 56 x 86mm
- B+ has slightly rounded corners
- The Rev 2 mounting holes have been removed
- New 4 mounting holes (2.5mm diameter) are provided, 3.5mm from the edges. 2 are in the left corners and the other 2 are just to the left of the USB and Ethernet sockets
- The GPIO connector is now 40 ways, with the first 26 pins being identical to the existing Model B so add-on boards can plug into just the first 26-pins
- The GPIO connector has moved away from the left hand edge by about 6mm, to allow for the corner mounting hole
- The USB connectors (2 of them now) have moved inboard so they protrude much less. The rear of them is still less intrusive than the Ethernet socket, but many existing add-on boards will collide with the new positions
- Many smaller add-on boards relied on capacitor C2 to provide a support, by using a rubber bumper/foot on the bottom of the add-on board. C2 is no longer present
- The composite video and audio connectors have been removed and replaced a a single low-profile, slimline socket which has been squeezed in between the camera socket and the ethernet connector
- The micro-USB connector has moved around the corner and turned 90 degrees
- Activity and power LEDs have moved to near pin 1 of the GPIO connector (and now are edge-lit)
- The Ethernet LEDs have moved onto the ethernet connector itself.
The diagram below shows the placement of the various items on both boards that could affect the fit and placement of add-on boards with the red line showing a possible shape of PCB that would be compatible with both Model B and Model B+. Download a dimensional drawing from here. Note especially that you should bring the board outline in, immediately after pins 25 and 26 on the GPIO socket, so allowing access to the remaining 14 pins on the new connector.
Existing 4tronix Add-On Boards
As this board used the full area around the composite video socket and inside the USB and Ethernet sockets, it doesn’t fit directly onto the Model B+. However, it is simple to attach an extending GPIO header and an additional 12mm spacer so that the board can be used perfectly well on a Model B+
Although the support pillar cannot be screwed into the non-existent mounting hole on the Model B+, they have at least left this part of the board clear, so there is no problem with the support pillar resting on the Raspberry Pi. It is imperative that you use the support pillar for this larger board. When purchasing a PiRoCon, you can specify “B+ Mounting Kit” and receive the extended header and 12mm male-female spacer for an additional £0.50 +VAT.
MicRoCon and Pi-Step
Whilst these can be fitted directly to the Model B+, they both used the rubber bumper on to the capacitor C2 to support them. There is no equivalent support position on the B+, so they have to be left unsupported, which is not a big problem especially if the connections are made before plugging in. I would recommend that the rubber bumper be moved over the HDMI scoket (as shown in the second photo below), so it prevents any possibility of shorting out if the board is bent over a long way
PiDie and PiRingo
The PiDie board “just” fits inside the Ethernet socket on the B+, as you can see from the photo below. The PiRingo fits without any problems. The support pillars for both boards can be used as it touches part of the Raspberry Pi board with no components, but of course it can no longer be screwed into the Pi.
IP Display Dongle and Adapter
There is no problem with this as it plugs directly onto the end of the GPIO connector. No changes required.
Initio Robot Chassis
The ABS moulding of course does not contain mounting holes for the new Model B+, but it can easily be adapted to fit using one of the offset spacers provided in every kit. There are several ways to fit the B+ onto the chassis, but the recommended position below allows the board to be supported in 4 corners, 2 of which have a screw in place. As with all boards mounted onto the chassis, you should remove the mounting positions that are not required so they don’t damage any components on the bottom of the Raspberry Pi board