Blackpool GNU Linux User Group

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// Where each of the pins on the arduino board is connected to the display header
#define CLOCKPIN   2  // PORTD (BIT 2)
#define DATAPIN    3  // PORTD (BIT 3)
#define BCD_ZERO   4
#define BCD_ONE    5
#define BCD_TWO    6
#define BCD_THREE  7
#define STRBPIN    8  // PORTB (BIT 0)

// Binary encoded font, each line of this array represents a character, each byte represents the 
// 8 bits that make up a row of that character

const static unsigned short font[95][8] =   
    { { 0, 0, 0, 0, 0, 0, 0, 0 },        // SPACE
      { 64, 64, 64, 64, 64, 0, 64, 0 },  // ! CHARACTER
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 56, 68, 76, 84, 100, 68, 56, 0 },     // NUMBER 0
      { 16, 48, 16, 16, 16, 16, 56, 0 },      // NUMBER 1
      { 56, 68, 4, 8, 16, 32, 124, 0 },       // NUMBER 2
      { 124, 8, 16, 8, 4, 68, 56, 0 },        // NUMBER 3
      { 8, 24, 40, 72, 124, 8, 8, 0 },        // NUMBER 4
      { 124, 64, 120, 4, 4, 68, 56, 0 },      // NUMBER 5
      { 24, 32, 64, 120, 68, 68, 56, 0 },     // NUMBER 6
      { 124, 4, 8, 16, 32, 32, 32, 0 },       // NUMBER 7
      { 56, 68, 68, 56, 68, 68, 56, 0 },      // NUMBER 8
      { 56, 68, 68, 60, 4, 8, 48, 0 },        // NUMBER 9
      { 0, 48, 48, 0, 48, 48, 0, 0 },         // : CHARACTER
      { 0, 48, 48, 0, 48, 16, 32, 0 },        // ; CHARACTER
      { 8, 16, 32, 64, 32, 16, 8, 0 },        // < CHARACTER
      { 0, 0, 124, 0, 124, 0, 0, 0 },         // = CHARACTER
      { 32, 16, 8, 4, 8, 16, 32, 0 },         // > CHARACTER
      { 56, 68, 4, 8, 16, 0, 16, 0 },         // ? CHARACTER
      { 56, 68, 4, 52, 84, 84, 56, 0 },       // @ CHARACTER
      { 56, 68, 68, 124, 68, 68, 68, 0 },     // UPPERCASE A
      { 120, 68, 68, 120, 68, 68, 120, 0 },   // UPPERCASE B
      { 56, 68, 64, 64, 64, 68, 56, 0 },      // UPPERCASE C
      { 112, 72, 68, 68, 68, 72, 112, 0 },    // UPPERCASE D
      { 124, 64, 64, 120, 64, 64, 124, 0},    // UPPERCASE E
      { 124, 64, 64, 120, 64, 64, 64, 0},     // UPPERCASE F
      { 56, 68, 64, 92, 68, 68, 60, 0 },      // UPPERCASE G
      { 68, 68, 68, 124, 68, 68, 68, 0 },     // UPPERCASE H
      { 56, 16, 16, 16, 16, 16, 56, 0 },      // UPPERCASE I
      { 28, 8, 8, 8, 8, 72, 48, 0 },          // UPPERCASE J
      { 68, 72, 80, 96, 80, 72, 68, 0 },      // UPPERCASE K
      { 64, 64, 64, 64, 64, 64, 124, 0 },     // UPPERCASE L
      { 68, 108, 84, 84, 68, 68, 68, 0 },     // UPPERCASE M
      { 68, 68, 100, 84, 76, 68, 68, 0 },     // UPPERCASE N
      { 56, 68, 68, 68, 68, 68, 56, 0 },      // UPPERCASE O
      { 120, 68, 68, 120, 64, 64, 64, 0 },    // UPPERCASE P
      { 56, 68, 68, 68, 84, 72, 52, 0 },      // UPPERCASE Q
      { 120, 68, 68, 120, 80, 72, 68, 0 },    // UPPERCASE R
      { 60, 64, 64, 56, 4, 4, 120, 0 },       // UPPERCASE S
      { 124, 16, 16, 16, 16, 16, 16, 0 },     // UPPERCASE T
      { 68, 68, 68, 68, 68, 68, 56, 0 },      // UPPERCASE U
      { 68, 68, 68, 68, 68, 40, 16, 0 },      // UPPERCASE V
      { 68, 68, 68, 84, 84, 84, 40, 0 },      // UPPERCASE W
      { 68, 68, 40, 16, 40, 68, 68, 0 },      // UPPERCASE X
      { 68, 68, 68, 40, 16, 16, 16, 0 },      // UPPERCASE Y
      { 124, 4, 8, 16, 32, 64, 124, 0 },      // UPPERCASE Z
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 0, 0, 0, 0, 0, 0 },
      { 0, 0, 56, 4, 60, 68, 60, 0 },         // LOWERCASE A
      { 64, 64, 64, 88, 100, 68, 120 },       // LOWERCASE B
      { 0, 0, 56, 64, 64, 68, 56, 0 },        // LOWERCASE C
      { 4, 4, 4, 52, 76, 68, 60, 0 },         // LOWERCASE D
      { 0, 0, 56, 68, 124, 64, 56, 0 },       // LOWERCASE E
      { 24, 36, 32, 112, 32, 32, 32, 0 },     // LOWERCASE F
      { 0, 60, 68, 68, 60, 4, 56, 0 },        // LOWERCASE G
      { 64, 64, 88, 100, 68, 68, 68, 0 },     // LOWERCASE H
      { 0, 16, 0, 16, 16, 16, 16, 0 },        // LOWERCASE I
      { 8, 0, 24, 8, 8, 72, 48, 0 },          // LOWERCASE J
      { 64, 64, 72, 80, 96, 80, 72, 0 },      // LOWERCASE K
      { 48, 16, 16, 16, 16, 16, 56, 0 },      // LOWERCASE L
      { 0, 0, 104, 84, 84, 68, 68, 0 },       // LOWERCASE M
      { 0, 0, 88, 100, 68, 68, 68, 0 },       // LOWERCASE N
      { 0, 0, 56, 68, 68, 68, 56, 0 },        // LOWERCASE O
      { 0, 0, 120, 68, 120, 64, 64, 0 },      // LOWERCASE P
      { 0, 0, 52, 76, 60, 4, 4, 0 },          // LOWERCASE Q
      { 0, 0, 88, 100, 64, 64, 64, 0 },       // LOWERCASE R
      { 0, 0, 56, 64, 56, 4, 120, 0 },        // LOWERCASE S
      { 32, 32, 112, 32, 32, 36, 24, 0 },     // LOWERCASE T
      { 0, 0, 68, 68, 68, 76, 52, 0 },        // LOWERCASE U
      { 0, 0, 68, 68, 68, 40, 16, 0 },        // LOWERCASE V
      { 0, 0, 68, 68, 84, 84, 40, 0 },        // LOWERCASE W
      { 0, 0, 68, 40, 16, 40, 68, 0 },        // LOWERCASE X
      { 0, 0, 68, 68, 60, 4, 56, 0 },         // LOWERCASE Y
      { 0, 0, 124, 8, 16, 32, 124, 0 },       // LOWERCASE Z
      
    };
                    
// The 8 fets controlling which row of the display is turned on are controlled by a BCD code 
// (Numbered 0-7). Therefore, using a value of 8 with this function turns the display off
void setActiveFET(int id)
{
    digitalWrite(BCD_ZERO, HIGH && (id & B00000001));
    digitalWrite(BCD_ONE, HIGH && (id & B00000010));
    digitalWrite(BCD_TWO, HIGH && (id & B00000100));
    digitalWrite(BCD_THREE, HIGH && (id & B00001000));
}

void pulseClock()
{
  // Pulse Clock Line On and then Off
  PORTD |= 1 << 2;
  PORTD &= ~(1 << 2);
}


void pulseStrobe()
{
   // Pulse strobe Line On and then Off
   PORTB |= 1 << 0;
   PORTB &= ~(1 << 0);
}

// Function to shift a single row of a single character into the registers
void shiftCharacterRow(char character, int row)
{
  // Shift the data into the display using bit manipulation for speed
  for(unsigned short i = 1; i < 8; i++)
  {
    short b = (font[character-32][row]) & (1 << (7 - i));
    if(b)
    {
      PORTD |= 1 << 3;
    } else {
      PORTD &= ~(1 << 3);
    }
    pulseClock();
  }
  
  // The arduino library includes a similar function for 
  // shifting data (good for testing, but too slow for 
  // persistence of vision)

}

void drawStringRow(char* string, int row, int length)
{
  for(unsigned short i=0; i < length; i++)
  {
    shiftCharacterRow(string[i], row);
  }
}

char text[49];

void setup()
{
  // Set pins 2 through 8 to be outputs as these interface with the display
  for(unsigned short i = 2; i<= 8; i++)
  {
    pinMode(i, OUTPUT);
  }
  
  // Enable serial communication for receiving messages from the computer
  Serial.begin(9600);
  
  // Initialise the array containing the message
  for(unsigned short i = 0; i < 49; i++)
  {
    text[i] = ' ';
  }
  
  // Default message for the display
  const static char* message = "Blackpool Computer Club";
  strcpy(text, "Blackpool Computer Club");
  
  
}


short curRow = 0;

void loop()
{
  unsigned int messageLen = strlen(text);
  
  // Buffer serial data one byte at a time
  char serialBuffer[2] = " ";
  if(Serial.available() > 0)
  {
    serialBuffer[0] = Serial.read();
    // Append it to the end of the display string
    strcat(text, serialBuffer);
    // If we're overflowing the display, blank the string
    if(messageLen > 48)
    {
      strcpy(text, "");
    }
  }  
  
  // Push the string into the display
  drawStringRow(text, curRow, messageLen);
  
  // Calculate the length of the string we're using and fill the rest of the display with 0s
  for(unsigned int i = 0; i < (384 - (messageLen*7)); i++)
  {
    PORTD &= ~(1 << 3);
    pulseClock();
  }
  
  // Enable the current row of LEDs
  setActiveFET(curRow);
  // Latch the current data so the display doesn't change while we're pushing the next row
  pulseStrobe();
  
  if(++curRow > 7)
  {
    curRow = 0;
  }
}

Blackpool GNU Linux User Group

Meeting Saturday 15th June 2013

Meeting Saturday 8th June 2013

LED wall display revisited

Project Brief : Produced by David M Hewitt

Design

Flow Chart

Reverse Engineering Methods

Preston Hackspace

Podcasts, command line and computer museum

LUG meeting 16th March 2013

23 March 2013 - Owncloud revisited

Pagekite revisited

Pagekite - The fast, reliable localhost tunneling solution

Northwest groups

Why use Linux?

Attracting members

Meetings

About us

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Developing Android Apps with Android X86 and Virtual Box

Debian Stable vs Ubuntu LTS for Server? - Ask Ubuntu

Linux cheat sheet

Blackpool LUG Meeting 2nd March 2013

Google drive sync app for linux

Raspberry Pi and RISC OS

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Burning arduino boot loader