Projects/CheeseBoard

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Contents

Overview

The 'Cheese Board' project aims to re-purpose (e.g. hack) a large LED display board from a golf themed arcade game and convert it into a networked device that can display messages sent from other devices around the hackspace (like the door entry system) or the Internet (using protocols like Twitter).

LED Display Board

The API for messages will be kept as simple as possible (e.g. formatted strings sent by UDP) to allow messages to be sent easy from embedded devices (like Arduinos) and/or programs/scripts running on other computers.

The name of project is in keeping with other 'cheesy' components proposed for the Hackspace Automation project.

Hardware

The LED display consists of one large panel with two rows of 5x7 common cathode LED matrix modules (Kingsbright TC20-11EWA)and their supporting high power shift register sinks (TPIC6B595).

The supporting micro-controller board hosted 7 PNP power transistors (TIP115) used to select the active LED row on the upper and lower display modules. The original board used a 20Mhz 68000 based micro-controller.

A 16-way wire connector links the two boards. After some reversing engineering the roles of the wires are as follows:

  1. Row 2 select (+12V)
  2. Row 1 select
  3. Row 3 select
  4. Row 6 select
  5. Row 4 select
  6. Row 7 select
  7. Row 5 select
  8. /G control input (5V)
  9. RCK control input (5V)
  10. SERIN for lower LED modules (5V)
  11. SERIN for upper LED modules (5V)
  12. SRCK for lower LED modules (5V)
  13. GND (connected to 16 on controller board)
  14. SRCK for upper LED modules (5V)
  15. VCC (+12V) for logic voltage regulator
  16. GND for logic voltage regulator

The female header connector uses a 16-Way Molex KK 3.96 housing (09-50-3161 - | RS 679-5517).

Proposed Design

The replacement board will be based on a dsPIC controller running at 3V3 to make interfacing to a ENC28J60 module easy. The connections to the display board will be controlled via a 74HCT244N line driver to convert the 3V3 control signals to 5V and a set of BC547B and TIP115 transistors will control the 12V row select signals.

A piezo buzzer will be included to allow new messages to announce their arrival.

Main Schematic LED Row Drivers

Message Format

To be completed.

{1D:Welcome To}{2:}{2U:Reading}{2U:Hackspace}{D:5}{3:Visit or website for more information}{D:5}{3:http://www.rlab.org/}

Status

24-11-2013: The remainder of the components have been added to the controller board and the 12V output and 3V3 to 5V level shifting has been tested. The initial draft of the LED multiplexing code has been written.

Control Board

13-11-2013: The dsPIC now correctly initialises the ENC28J60 and received IP packets into its memory buffer. Additional UDP/IP decoding is needed and support for a PING echo response.

Contacts

For more information contact either:

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