Model B+ Raspberry Pi Mounting Issues

14th July 2014

Click on any image to enlarge

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

1. Both boards are the same nominal size at 56 x 86mm
2. B+ has slightly rounded corners
3. The Rev 2 mounting holes have been removed
4. 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
5. 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
6. The GPIO connector has moved away from the left hand edge by about 6mm, to allow for the corner mounting hole
7. 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
8. 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
9. 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
10. The micro-USB connector has moved around the corner and turned 90 degrees
11. Activity and power LEDs have moved to near pin 1 of the GPIO connector (and now are edge-lit)
12. 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

PiRoCon 1.2

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

IP Display Dongle – Usage & Software

(Click on any image to enlarge)

The IPDisp V1 is a 4-digit 7-segment LED display utilising a “retro” LED of the type found in 1970s calculators. This makes for a cute little display device that can be used to display anything you like that will fit in a 7-segment display. V2 uses a standard 7-segment display which is slightly larger. Both PCBs are the same size: 40 x 32mm (width x height).

You can purchase it here at 4tronix.

It was conceived as a device to help roboteers find the IP address of their robot so that they can connect to it via SSH or VNC for control purposes. Of course you can use a network scanner such as the excellent Fing, but that can become unwieldy in a corporate or educational establishment with a lot of connected devices. This unit is much more fun and can be setup to display the IP address directly on boot up.

IPDisp uses an I2C Port expander chip, the MCP23017, to address all the segments (anodes) as well as the individual common cathode digit drivers. The provided software, in Python, time-multiplexes the digits so that each digit is displayed for only 25% of the time.

Connecting the IP Display Dongle

The pinout is designed to match the I2C expansion socket on every 4tronix robotics controller board: PiRoCon, MicRoCon, Pi2Go and PGX. Simple select the type of header you want to use and solder it on. You may want it to lie flat, stand vertical, lie flat but higher up (extended header), etc. Then, making sure that you have it correct way round, plug it directly into the I2C expansion header. Here we show it plugged vertically into the I2C expansion connector on a MicRoCon controller board.

We also include female headers in the package, so you can plug into a male header, or use male-ended jumper wires to connect to your I2C pins. In fact, apart from the 5V connection, the layout of the pins matches the standard GPIO header on the Raspberry Pi, pins 1, 3, 5 and 7. So plug the header in to the pins as shown below, with the 5V pin hanging off the end. You then have 2 choices:

1. Use a male-female jumper wire to connect the 5V on the IPDisp to Pin 2 on the GPIO header
2. Solder across the last 2 pins (5V and “not connected”). This powers the IPDisp off the 3.3V from the Raspberry Pi. Although it “works”, it is not recommended except frr emergencies as it does use too much power for continuous use.

Option 1

Option 2

Running the Software

Make sure that you have the I2C drivers enabled on your SD card. If not, follow this post by Raspi.TV

Download the python sample file and run it using sudo python ipd03.py:
$ cd ~
$ mkdir ipd
$ cd ipd
$ wget http://4tronix.co.uk/ipd/ipd03.py
$ sudo python ipd03.py

This will display the IP address and scroll it across the display a number of times, before quitting. If the Pi is not connected to a network, then it will display 0-0-0-0 and wait until the network is connected before displaying the correct IP address. As the continuous updating of the display is processor intensive, we don’t leave it running permanently.

The current version of the software will exit with an exception if the IPDisp is not connected. We didn’t bother to catch the exception as the information is what we need anyway.

Of course, this is not a lot of use  like this because we must already be connected, or running locally when running the application like this. It is much more useful to get the program to autostart when the Pi boots up. To do that follow the instructions to instigate a startup program when the desktop starts. (you can also put the code in the startup list, but we’ll do it like this for now)

Open LXterminal

$ cd ~    (back to home directory)
$ cd .config
$ mkdir autostart   (not required if it already exists)
$ cd autostart
$ sudo nano ipd.desktop

…and enter the following lines. Note that the Exec line needs to have the correct location for where you have put the program.

[Desktop Entry]
Encoding=UTF-8
Type=Application
Name=IPDisplay
Exec=sudo python /home/pi/ipd/ipd03.py
StartupNotify=false
Terminal=false
Hidden=false

Exit (ctrl-x) and save (y) then reboot. The IPDisplay will show the IP address of the Pi.