hp Bubble Display Controller

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This is a board and firmware project supporting hp's 4 digit 7 segment LED bubble display, QDSP-6064, available from SparkFun. The project is intended to enable a pair of displays to be easily connected over a two-wire I2C bus to a microcontroller (e.g. Arduino). The board is also an example circuit of how to get reasonable brightness from these small displays. By having a separate microcontroller driving the display, the burden (I/O pins, code space & CPU cycles) on the main application microcontroller is reduced.

For a more detailed write-up of the project see "Forum Postings.pdf" in the repo or see this thread on the SparkFun forum.

Here is a photo of the functional display.

This repo includes Eagle CAD PCB design files for the board, and Arduino source code for controller firmware and interface library with examples. The board acts as an I2C slave driven from another microcontroller as I2C master.

Order PCBs

You can order this PCB directly from OSH Park. Click on the following link.

• Bubble Display Controller - http://oshpark.com/shared_projects/Lmfa2Fmm

See Bill of Materials file in repo for parts list.

Status

• 07APR2014 PCB received built and tested good.
• Firmware, library and examples have been completed and tested against the final PCB.

File Formats

Design files are in "CadSoft EAGLE PCB Design Software" .brd and .sch formats.
A free version of the software can be downloaded from www.cadsoftusa.com.

schematic

PCB

Firmware, library and examples were developed using the Arduino 1.0.5-r2 IDE and the source files are in Arduino .ino format (and .h or .cpp formats as applicable).

Distribution License

You may use this PCB design and source code however you like but no liability is accepted.

Attributions

The hardware design has roots in the SparkFun RedBoard design.

The firmware is based on the slave_receiver.ino example and relies upon the wire library from Arduino, both included as part of the Arduino distribution. The SparkFun tutorial Using the Serial 7-Segment Display was reviewed with an eye toward creating a compatible interface, but in the end it was decided to implement a driver library instead. Still the tutorial may have influenced this design. The BubbleDisplay library interface and code were modeled after the Arduino LiquidCrystal library.

Notes:

This controller board has no serial port for connecting to the Arduino IDE. The controller firmware is programed using an ISP programer such as the Pocket AVR Programer from SparkFun.