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:: Research Group Embedded Interaction :: Media Informatics :: Ludwig-Maximilians-University Munich

Particle Display Add-On

This add-on board can be clipped onto a Particle (version 229) via a Conan connector. On the board, there is one accelerometer, ADXL311JE and it provides connector for up to 6 displays. Alternatively, one display can be directly soldered on the board. This gives a very compact layout (about 50 x 40 x 20 mm, width x breadth x height, including one AAA battery. A second accelerometer can be attached orthogonally to the first one without enlarging the dimensions.

Especially useful for working with the display is the DisplayServer project. It provides access to many methods of writing to the display via a webserver, i.e. the HTTP protocol. Any software that is able to access the webserver can easily use the display.

Please also consult the DisplayServer page, out Particle How-To and the Particle Software page.

Files - Code and Headers

The code and headers follow the particle architecture and separates board and code. It also provides the necessary functions to turn board and sensors on and off and to initialize the components.

• Code and header for Barton BT96040 chip-on-glass display bt96040_ds.c bt96040_ds.h
• Code and header for Add-On Board bt96040-addonboard.c bt96040-addonboard.h
• Code for the ADXL311JE sensor adxl311je.c

When programming a particle with the graphics code from the DisplayServer page, the methods defined in display.h and display.cpp can directly be used. An example program can be found here:

• Code that illustrates the use of display interface methods: dispsend.zip
• The files that pass commands (like d_line, d_text, etc.) to the particle: display.h, display.cpp

Files - Boards and Schematics

• Eagle files for Particle Display Add-On:
  display.brd, display.sch
   
• (optional) Eagle files for connecting a second accelerometer to the board:
  adxl311.brd, adxl311.sch
   
• (optional) Eagle files for connecting a display to a Molex connector:
  display-molex.brd, display-molex.sch

Components and Costs

The following parts are needed to solder the board. For the minimalist version of this board, i.e. only one accelerometer and one display, you can leave the optional parts (Molex Connectors, second ADXL311JE, etc.). Costs given are approximate only and may apply for larger orders only.

OPTIONAL: The ADXL311 board is only needed if you want to add a second accelerometer that is positioned orthogonally to the one on the main board.

OPTIONAL: The six Molex connectors are only needed if you want to connect several displays or one by wire. The most compact version is achieved by directly soldering the display on the board.

Detailed Soldering Instructions

If you follow the instructions, you may get a result that looks like the following image:

• Begin by soldering the ADXL311. Check the direction: On the bottom of the sensor, there is a small dot that is reproduced in the eagle board file.

• Next add the 7 resistors with value 3K3 (3300 Ohm).

• Put the 220 kOhm resistors on the board.

• The LTC1261 is put at the right bottom of the board.
   
• Now place the 9 capacitors as shown in the picture

• On the top right of the board, you can put a potentiometer that controls the contrast of the display. We chose to just directly bridge it as can be seen in the picture to get maximum contrast.

• You can decide whether or not you want to be able to switch the displays on and off via the PIC. When inserting the bridge as shown in the picture, the LCD will always be served its (negative) voltage. If you bridge the central with the upper pin, use PIN_CONN_17 to switch it on or off. Currently we have switched our displays on permanently.

• On the back of the board, the Conan connector can be soldered. It should fit in one direction only: If you put the board on the table as shown in the picture, there should be 10 connections to the left and 11 to the right.

• One display can be soldered directly on top at the five pins.
   
• If you want to add more displays, put Molex connectors on the board and connect displays using the Molex-Display boards described above.
• Now you can solder the adxl add-on to the display board.

• Please notice the small point on the adxl and how it is to be soldered to the board..

• The adxl add-on is to be connected as follows to the base board (right in the image).

• And with the Molex connectors, the add-on board is finished.
   

Here are some images of a completely equipped add-on board including particle and power supply using a AAA battery.

     
Top and bottom views: The picture on the right mainly shows the particle and the battery holder where we additionally attached a small power switch.

     
Side views. In the version on the picture to the left we actually soldered a small connector to be able to take the display off. The small blue box on the left is a potentiometer used to control the contrast of the display. As mentioned above, this is normally not necessary and the pins can be directly bridged.
The five Molex connectors can be seen on the image to the right.

This picture shows how the second accelerometer is attached to the main board. The white Molex connector to the right of the accelerometer board is only used if the display were not soldered directly on the main board.