Sunday, January 10, 2016

Meet Fobble - a general purpose Wireless Breakout Board!

Fobble - A General Purpose Wireless Breakout Board

This week I have been working on another of my standard footprint 50mm x 50mm boards - it is a general purpose wireless module carrier board:-  Fobble.  That's a BLE Fob - for anyone who misses the pun.

In the last few weeks there have been a number of applications arise - that could easily be addressed with an easy to use, generic wireless platform. These have included keyfob or pendant applications - requiring a small coin cell powered board - to a generic wireless board that can be stacked to one of the processor boards to provide wireless connectivity.

So after a week of head-scratching, I have come up with a small board, which at least meets the requirements of the development phase of the project - once again a useful, flexible dev-board that hobbyists can experiment with.

As can be seen from the above picture it contains a number of key features:

  1. A resident RFduino  Bluetooth Low Energy Module with ARM Cortex M0 processor
  2. 2 layer pcb 50 x 50 mm format- with extended Arduino headers pin-out
  3. An X-Bee footprint - with 0.1" breakout headers - to add your own wireless module
  4. Two push button switches - only 1 populated shown
  5. Footprint for RGB 0505 LED
  6. Detachable power and programmer section
  7. Detachable side panels - to make 38 x 32 mm BLE Key Fob 
  8. 8 pin header to accept 1.3" OLED display
  9. 20mm coin cell or flat Li Po cell power - on rear of Fob pcb
  10. Micro - USB connector for recharging Li Po
  11. Side Prototyping areas - perforated in 0.1" matrix
  12. 7 pin and 5 pin headers to accept any RFduino accessory shields - for development work

Some applications include:
  • A low power wireless data display using BLE and either OLED or e-ink display.
  • A BLE key fob, or wearable pendant with 2 user buttons and an RGB LED
  • A bridge between BLE and low power 433Hz or WiFi
  • As a wireless shield for an Arduino compatible device
  • As a general purpose Experimenter's BLE dev-board.
The other unique feature about Fobble, is that it has it's own native ARM M0 and Bluetooth Low Energy module, and can act as a bridge between Bluetooth, and any other wireless module that you may wish to use.

It can accept any wireless module that offers an XBee footprint - or a wireless daughter module of your own making - pinned out to 2,  10 pin headers  on 1.1" centres.  This simple scheme offers the most flexibility. So you can add an ESP8266 on an X-Bee format carrier, or similarly an RFM69.

Fobble is pin compatible with the standard Arduino header footprint, and will also accept a 3.3V FTDI cable for programming.

Small & Versatile

With side-wings removed Fobble becomes a compact 32 x 50 pcb

As can be seen from the above layout plot and the vertical parallel white lines, the centre section of Fobble is perforated with a line of holes - so that the outer wings that carry the Arduino headers may be snapped off. Additionally the bottom section that has external power supply components may also be broken off to leave a 32 x 38 mm section that can be mounted in a small key fob style case.

Another feature of Fobble is that you can  plug in a low cost OLED graphic display - and create a Bluetooth message display.  The display chosen is the Adafruit 1.3" diagonal OLED display but other similar displays may be used with minimum changes to the wiring.

The availabilty of pluggable headers, plus the uncommitted Arduino pin headers mean that Fobble may be used to prototype new wireless ideas - just by using jumper wires, or a breadboard.

The onboard module is the RFduino - based on an ARM M0 processor - the Nordic Semiconductor nRF51822.  This is programmable via the Arduino IDE and can make use of the Adafruit OLED graphics libraries.


Fobble recreates the standard 7pin - 5pin header pattern used by the RFduino Ecosystem - thus allowing any of the existing modules to be plugged in - including the USB programmer - or you can just use a serial programming cable that has RTS for resetting the board - such as FTDI cable or CP2102 adaptor board. A wide variety of prototyping modules are available in this format - produced by RFDigital - and distributed by RS, Mouser, Digikey etc.

Fobble can be used with these open source Arduino communication boards.

PCB Layout

Fobble - the latest 50x50 format board for Wireless Breakout 

Here's a shot of the layout of the 50x50 pcb - showing the white lines where the board is perforated to allow the side wings and the lower power-supply programmer section to be snapped off.  The 2032 coincell is mounted centrally on the underside of the Fob section.

Stop Press!

The company behind the RFduino have just announced a new BLE module called Simblee
It shares the same development module as RFduino - and now available from Digikey and Mouser  - Exciting times ahead!

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