====== LED Matrix Projekt ======
{{tag>project hardware electronics software}}

===== Goal =====

The goal is to build up a 32x8 LED matrix with THT parts that you can buy at your local dealer.
Currently it uses 4 74HC595 shift registers and 2 4017 decade counter to control the matrix.
Controlling the LED matrix should be done with an AtMega32 and an AtMega8 for USB to seriell communication.

===== Parts needed for the matrix =====

  * 4x 74HC595 shift registers 
  * 2x 4017 decade counters
  * 32x 160 ohm resistors
  * 16x 1k ohm resistors
  * 2x 5x2 pin headers
  * 256x LEDs (color: red)

===== Parts needed for the controller =====

Nothing there yet.

===== USB interface =====


==== Short description ====

The USB interface is build after schematic of [[http://www.recursion.jp/avrcdc/cdc-232.html]] and uses the same firmware.
The communication between the AtMega8 and the AtMega32 is done via normal UART communication.

To control the LED matrix from the PC, the user must send normal text commands and binary image data.

===== Command structure =====

There are two types of commands. Single line commands and block commands.
Each command start with a 3 byte header and consists of a 3 byte text command followed by the data.

While single line commands ends with a normal line break, block commands must end with the 3 byte text command followed by the 3 bytes header.

The 3 header bytes read //LED//.

Format of single line command: LED//COMMAND//**DATA**

Format of block command: LED//COMMAND//**DATA**//COMMAND//LED

===== Commands =====



==== Clear ====

Clears all pixels on the LED Matrix.

  Command: CLR
  Data: none

Usage: LEDCLR

==== Set Pixel ====

Sets one pixel on the LED matrix indicated by X and Y coordinates.

  Command: STP
  Data: COORDINATES (1 Byte)
  
Usage: LEDSTP//COORDINATES//

The lower 5 bits of the coordinates parameter describe the X coordinate to set.
The upper 3 bits of the coordinates parameter describe the Y coordinate to set.
All counting starts at zero (0 <= X <= 31; 0 <= Y <= 7).

Examples:

  * LEDSTP0 (001 10010) Set Pixel at X = 18 Y = 1
  * LEDSTPA (010 00001) Set Pixel at X = 1 Y = 2
  * LEDSTP! (001 00001) Set Pixel at X = 1 Y = 1
  * LEDSTP* (001 01010) Set Pixel at X = 10 Y = 1



==== Clear Pixel ====

Clears one pixel on the LED matrix indicated by X and Y coordinates.

  Command: CLP
  Data: COORDINATES (1 Byte)
  
Usage: LEDCLP//COORDINATES//

The lower 5 bits of the coordinates parameter describe the X coordinate to set.
The upper 3 bits of the coordinates parameter describe the Y coordinate to set.
All counting starts at zero (0 <= X <= 31; 0 <= Y <= 7).

Examples:

  * LEDCLP0 (001 10010) Clear Pixel at X = 18 Y = 1
  * LEDCLPA (010 00001) Clear Pixel at X = 1 Y = 2
  * LEDCLP! (001 00001) Clear Pixel at X = 1 Y = 1
  * LEDCLP* (001 01010) Clear Pixel at X = 10 Y = 1



==== Toggle Pixel ====

Toggles one pixel on the LED matrix indicated by X and Y coordinates.

  Command: TGP
  Data: COORDINATES (1 Byte)
  
Usage: LEDTGP//COORDINATES//

The lower 5 bits of the coordinates parameter describe the X coordinate to set.
The upper 3 bits of the coordinates parameter describe the Y coordinate to set.
All counting starts at zero (0 <= X <= 31; 0 <= Y <= 7).

Examples:

  * LEDTGP0 (001 10010) Toggle Pixel at X = 18 Y = 1
  * LEDTGPA (010 00001) Toggle Pixel at X = 1 Y = 2
  * LEDTGP! (001 00001) Toggle Pixel at X = 1 Y = 1
  * LEDTGP* (001 01010) Toggle Pixel at X = 10 Y = 1