BeBoPr Bridge

Bas Laarhoven edited this page Sep 5, 2013 · 10 revisions

2013-09-05 Added Major League connector part numbers.

2013-08-20 The board is now available as shared project at OSH Park. For details at the end of this page.

2013-08-11 The Revision 1 boards are now available. A bit smaller in size, larger pads for the wires, better readable legend. Still having ENIG (gold) finish for easy soldering. Transfer EUR 8.50 with address details via PayPal to receive a set in your mailbox (price includes shipping worldwide).

The 'BeBoPr Bridge' is based on a simple set of small PCBs as shown below. This design is 'Open Source Hardware' and the design information and Gerbers are available for download here. These PCBs handle all the signal re-routing needed to make the BeBoPr fully compatible with the BeagleBone Black.

The PCBs can be assembled as a separate 'BeBoPr Bridge' module. The white spacers shown on some photos are not needed, these were installed to provide some rigidity during the photo shoots. The 10-wire flex cable can be replaced by a piece of 2.54 mm / 0.1 inch pitch flatcable or by 10 separate wires. The cable/wire length should be 50 mm or 2 inch.

The Bridge can be used on both the original/unmodified BeBoPr and on a BeBoPr that has the enable patch installed.

BBR_R1, second generation

Revision 1 Bridge

The asymmetry of the second generation boards makes orientation mistakes less likely. The extra space generated by the Bridge makes the RS232 console cable fit underneath the BeagleBone as shown in the picture below.

Bridge with console cable

BBR_R0, first generation

BeBoPr Bridge Module

The BBR_R0 Bridge needs either one or two solder bridges / jumpers installed. When used with a BeBoPr that has the enable patch installed, add a solder bridge between P8 pin 5 and P8 pin 7. The other solder bridge on the P9 board looks like an SMD component footprint and should be closed in all situations. Revision 1 boards have both bridges integrated on the PCB.

Use with other capes

Although the BeBoPr is using many of the available signals and resources from the BeagleBone. Using the Bridge, some other capes may work if mounted between the BeBoPr and the Bridge. The LVDS cape is an example as can be seen here. Don't forget to set the cape addresseses properly!

Assembly

Besides the Bridge PCBs, a number of connectors are needed (pin headers and sockets) and some wiring to route the signals between the boards. The picture below shows the parts that were used to build the first bridges. A single 2x100 pin header, two 2x32 pin sockets, a 10 wire flex jumper and the bridge PCBs. Use these parts or similar ones (order numbers for Farnell/Element14):

sockets 2x32 pos, order no. 1569233
header 2x50 pins, order no. 3418560
jumper strip 10 way, order no. 1310333

Instead of the nice but expensive PTFE flex jumper strip, a cheaper version can be found at Mouser:

STD cable jumper 10 way, order no. 538-25001-1002

All connectors do have to be cut at the proper length (2x23 pins).

The following connectors from the Major League BeagleBone connector webshop have a good price and should also fit. Can someone confirm these part numbers?. For a compleate Bridge order two of each, no cutting needed!

sockets 2x32 pos part no. SSHQ-123-D-06-G(T)-LF
headers 2x32 pos part no. TSHC-123-D-06-240-G(T)-LF

Some assembly tips:

  • Bend the pins at the extremes (pins 1-2 and 45-46) of the connectors slightly inwards so that the boards clamp between these pins. This makes further assembly easier.
  • Plug a socket connector on the header pins while soldering these to a board. This will keep the pins in position if the plastic of the header softens.
  • Use a small hacksaw to separate the two bridge boards. Remove the remaining material with a smooth file.
  • Use the same saw to cut the socket connectors at length if these are too long. Clamp the connector in a vice with the solder pins pointing down. Insert a header connector that's already cut to the proper length. Carefully cut into the socket connector, in the middle of the pins next to positions occupied by the header. Don't worry about the metal of the pins.

When assembling the Bridge or when plugging it onto the BeBoPr, make sure to always use the references on the Bridge PCBs for orientation. The PCBs have connector P8/P9 and pin number references on both sides. Align these with the connector markings on the BeBoPr or BeagleBone. The markings on the first generation Bridge boards were a bit hard to read because of the solder mask, the new (revision 1) boards don't have this problem.

The picture below shows the first generation (BBR_R0) PCBs next to the somewhat smaller revision 1 (BBR_R1) boards.

BeBoPr Bridge PCBs

Ordering at OSH Park

Via this link you can order three boards for USD 19.45 (price at 2013-08-20), or download the design files and do your own processing. The OSH Park boards have a nice purple solder-mask instead of the normal (boring) green, and combine nicely with the BeagleBone Black. Not only the boards are purple, as can be seen below!