LED moving font

 

The LED moving font is built up of separate modules consisting of 64 LEDs each (8x8 matrix). The modules can be cascaced according to the desired size of the font. Each module is controlled by the LED display driver MAX7219 (or MAX7221) which can drive 64 LEDs. The display data is transferred serially to this display driver via the pins DIN, CLK and LOAD. The pin DOUT can be connected to the input DIN of the following display driver, all CLK and all LOAD pins are connected together. The datasheet is available on Maxim's homepage.

The modules are controlled by an 8051-compatible microcontroller AT89C51 (LED moving font controller variant 1) or AT89C2051 (LED moving font controller variant 2) from Atmel which provide 4 kB or 2kB flash memory on-chip. The LED display driver MAX 7219 CNG is available from Reichelt or Segor, a free sample can be ordered on the homepage of Maxim. The LED display driver is mounted together with a LED module (8x8 matrix) on the LED module PCB.

The display text is stored in a EEPROM. The text can be downloaded via a serial RS232 connection from a PC. From the PC a text file containing the text is sent. The baudrate can also be set to 600 Baud (via additional jumper), because some PCs have problems with hardware handshaking, which would be necessary at 1200 or 9600 Baud download speed. Dependent on the storage size of the EEPROM up to 2045 characters can be stored. It is also possible to store the text in the flash ROM of the microcontroller. But then it is necessary to reassemble the program code if the text is changed and to reprogram the flash ROM. If an EEPROM is used, changes of the text can be done easily via serial downloading. A maximum of 11 LED modules (each module consisting of 8x8 LEDs) can be used. The moving font is already working with 1 module.

Adjusting moving speed: in EEPROM-Mode, 255 speed values can be set. The selected value can be transmitted via serial interface and will be stored in a byte in EEPROM.

The schematic and the software can be downloaded here:

Project files for hardware and software in ZIP format:
LED moving font V2.3

For the hardware the freeware version of Eagle 3.55 is required. It is available for free from CadSoft.

Schematic and component placement in GIF format:
LED moving font controller variant 1 (for AT89C51):
Schematic of LED moving font controller variant 1
Component placement of LED moving font controller variant 1
LED moving font controller variant 2(for AT89C2051):
Schematic of LED moving font controller variant 2
Component placement of LED moving font controller variant 2
LED module:
Schematic LED module
Component placement of LED module

Printed circuit board:
There are professionally manufactured unpopulated printed circuit boards available for this project, named:
MAT_CON1.BRD (LED moving font controller variant 1 for AT89C51)
MAT_CON2.BRD (LED moving font controller variant 2 for AT89C2051)
LEDMODUL.BRD (PCB for 1 LED module TC23-11EWA)
More information is available here: Printed circuit boards for WOE projects

Programmed microcontroller:
If you are interested in a programmed microcontroller, please send an email including the project name.

Did you like this project?
So feel free to support WOE with a small donation. You will support the development of further free projects on this site. Thank you.

Suitable 8x8 LED dot matrix displays for the LED moving font:
For each LED module a 8x8 LED dot matrix display is required with common cathode columns and common anode rows. You can build the dot matrix displays with seperate LEDs on a universal PCB or you can use 8x8 LED dot matrix panels. A suitable type is the display TC23-11EWA manufactured by Kingbright, a suitable unpopulated PCB is available, look ahead. The color of this LED dot matrix display is red, but it is also available in different colors.

Sources of supply for 8x8 LED dot matrix displays TC23-11EWA:
8x8 LED dot matrix displays TC23-11EWA (Manufacturer: Kingbright, color: red, technical data) are available via the distributors of Kingbright, e.g. menges electronic. 

Ref: woe.onlinehome.de/e_projects.htm

LED Photo Sensor

Here's a circuit that takes advantage of the photo-voltaic voltage of an ordinary LED. The LED voltage is buffered by a junction FET transistor and then applied to the inverting input of an op-amp with a gain of about 20. This produces a change of about 5 volts at the output from darkness to bright light. The 100K potentiometer can be set so that the output is around 7 volts in darkness and falls to about 2 volts in bright light.

ref: bowdenshobbycircuits.info/page8.htm#db.gif

Hacked LED Mouse Light

Written by: Alan Parekh

Most of us have a bunch of these old mice laying around collecting dust. If you didn’t make some cool art with your mice last week here is another idea to recycle it into a cool project. This article will show you how to turn an ordinary mouse into a flashlight, perfect for looking into computer cases that always seem to be in the darkest corner of the room.

You will only need a few items for this hack.
* 360 Ohm resistor
* 9 Volt Battery Snap
* Heat Shrink (optional)
* White LED

This is the basic single LED version. A more elaborate version will be documented in the near future. Look at the bottom of this article for a sneak peak of the high end version. 

Look to see how to crack the mouse open. Most have some visible screws on the bottom. This one doesn’t…

After removing the glider pads the single screw is revealed. Removing this screw is all it takes to open the case.

This is a typical mouse. Lots of room and a big roller ball in the middle.

Start carefully removing the guts. Most of the components in this one were just slotted into place.

To make room for this mod the circuit board will be cut. This is also a convenient way to disconnect the switch that we will be using from the original circuit.

As you can see with the modified board installed there is now lots of room to play with.

A plastic fin on the top cover had to be trimmed to allow the battery to be installed. A simple snip of the side cutters is all it took.

There was also a small clearance issue with the side of the battery, we need this extra room since there will be a battery snap attached to the battery. Again the side cutters made easy work of the plastic fin.

I decided to use the original wire grommet as the LED hole. The wire diameter is smaller than the 5mm white LED that will be installed.

The drill press is overkill to enlarge the hole but it was handy.

The base of most LEDs have a flange, to accommodate this I simply used the tip of a soldering iron to melt away a some of the back of the grommet.

This mouse is designed quite well, the grommet slides right back into place with ease.

The LED is now slid into the grommet. Use a bit of hot glue if it is a loose fit, in this case it is held in there quite well with no glue.

Next we will solder some current limiting and one battery snap lead to the mouse switch. I am using the left click switch in this case. It is usually very easy to tell where to solder to since most mouse circuits use only N/O (normally open) switches which is what we need. If the switch has three connection you are usually safe to use the same ones that the original mouse circuit used.

Next I used some heat shrink to cover the resistor and bare wires.

Some wires are now connected to the LED and heat shrink is used to cover the bare wires. Red from the battery snap and the wire from the switch are used.

That is the entire circuit done. You can connect the battery now and give is a test.

Another shot from the side.

Slide the board back into place. Depending on the model of mouse you may need a bit of hot glue to hold it in place. For this one that was not required.

It is possible to have both switches control the single light, all you need to do is jumper the two switches together.

Since we are going to keep the roller ball in place make sure it will not rub on the wires when the unit is closed up.

Connect the battery. In this case it fit quite well, if the case is a bit larger you might need some foam to keep it from bouncing around inside.

Close the lid making sure not to pinch any wires.

That’s it, you now have a new flashlight.

Looks a bit like one of the old optical cordless mice from the front. In fact when it was sitting on the desk I have grabbed it a few times and wondered why the mouse cursor wasn’t moving on the screen…

Give it a push and make sure it works.

Now when you are working on your computer you can use a light that is cool and functional.

---

Here is a sneak peak of the next version of the LED mouse.

This is a three button mouse that controls four white LEDs and four UV LEDs. The UV LEDs are on the bottom and are used to check for counterfit money, cheques etc.

ref: hackedgadgets.com/2006/06/15/hacked-led-mouse-light