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mbed-BoB2

  1. mbed-BoB2
    1. History
    2. Manufacture
    3. Ordering
    4. Bill Of Materials
    5. Eagle Files

This page is all about BoB2 - the second generation.

The PCB is available at http://www.batchpcb.com/index.php/Products/24821

History

The first incarnation of the mbed Break out Board (mbed-BoB) was good, but some parts of it were better in theory than in practice, and there were parts that were plain wrong.

You can read about the first generation here:

So, we took a long hard look at BoB, and decided on the following changes :

We removed :

  • Battery box
  • Power Over Ethernet module
  • Switch
  • DC Jack
  • Those fiddly BAT60 diodes that were a pain to get hold of

We kept :

  • The neat double row headers for the mbed
  • Ethernet
  • USB-B
  • Servo/PWM headers
  • 3.5mm mono jack sockets (x2)
  • 2 way DIP switch
  • Push button (x2)
  • 12mm coin cell holder for a CR1216
  • Micro SD card socket (its SMT, not too fiddly, and completely worth it)

We added :

  • 2 way screw terminal for additional power in
  • Silkscreen labels so it was obvious what connects to what

We changed the layout :

  • The buttons can now be pressed
  • It is nice and compact
  • There are no special assembly orders

mbed-BoB2 Schematic

mbed-Bob2 Layout

Manufacture

This time around, we decided it would be good to upload and publish the design via BatchPCB so that anyone can order, build and own thier very own BoB2

Doing this wasnt without its hurdles. Usually making a PCB means sending off the .brd file to PCB Cart, they make all the gerbers and drill files and send PDFs of the results for you to approve. Batch PCB is a little more low end that that. Make your own gerbers, sanity check them yourself cos they will make what you send :-)

I have a few issues with generating the gerbers and getting them through DRC. The Eagle section below contains the files for the design, and the CAM job file that makes all the gerber files in the right format and so on.

Ordering

If you want to order an mbed-BoB2 PCB, you'll need to do the following

DISCLAIMER: We've not tested this board design yet

Bill Of Materials

Component Description Rapid Farnell
BAT CR1216 Coin cell holder 18-3610
C1 10uF 11-1220
CON1 RJ45_POE 1284349
CON2,3 AUDIO_JACK 20-0137
CON4 SF-MICROSD 1366700
CON5 USB-B-H 24-0346
IC1 MBED-SOCKET 22-5144
J1-6 PINHD-1X3 22-0500
R1-4 4k7 62-0386
D1,2 1N4001 47-3130
SW1,2 Push button 78-0620
SW3 2way DIP Switch 80-0300

Eagle Files

Attachments