Matriz de LEDs 8x8 com MAX 7219

Neste projeto será utilizado o MAX7219 que permite o acionamento de displays de LEDs. Com ele é possível  acionar até 8 displays de 7 segmentos ou uma matriz de LEDs de 8X8. A entrada de dados é feita de forma serial, reduzindo a quantidade de pinos do microcontrolador. São utilizados apenas 3 pinos para interface com o microcontrolador, DIN, CLK e CS.  O pino DIN é utilizado para inserir os bits (16 bits), que é sincronizado pelo pino CLK, o clock de sincronismo definido pelo microcontrolador. O pino CS é utilizado para transferir os 16 bits inseridos para o display. 

A ligação do Módulo MAX 7219 é bem simples, conforme mostrado na figura abaixo:

Após conectar os fios, carregue o código:

  1 

  2 

  3  /* Este programa permite exibição de uma mensagem com rolagem horizontal*/

  4 

  5  # include <avr/pgmspace.h>

  6  # include <TimerOne.h>

  7  # define DataPin  2 // Porta 2 do Arduino ligada ao DIN

  8  # define CSPin    3 // Porta 3 do Arduino ligada ao CS

  9  # define ClockPin 4 // Porta 4 do Arduino ligada ao CLK

 10 

 11  byte buffer[8];

 12  const byte font[][8] PROGMEM =

 13 

 14  {

 15      {B00000000, B00000000, B00000000, B00000000, B00000000, B00000000, B00000000, B00000000},

 16      {B00000100, B00000100, B00000100, B00000100, B00000100, B00000100, B00000000, B00000100},

 17      {B00001010, B00001010, B00001010, B00000000, B00000000, B00000000, B00000000, B00000000},

 18      {B00000000, B00001010, B00011111, B00001010, B00011111, B00001010, B00011111, B00001010},

 19      {B00000111, B00001100, B00010100, B00001100, B00000110, B00000101, B00000110, B00011100},

 20      {B00011001, B00011010, B00000010, B00000100, B00000100, B00001000, B00001011, B00010011},

 21      {B00000110, B00001010, B00010010, B00010100, B00001001, B00010110, B00010110, B00001001},

 22      {B00000100, B00000100, B00000100, B00000000, B00000000, B00000000, B00000000, B00000000},

 23      {B00000010, B00000100, B00001000, B00001000, B00001000, B00001000, B00000100, B00000010},

 24      {B00001000, B00000100, B00000010, B00000010, B00000010, B00000010, B00000100, B00001000},

 25      {B00010101, B00001110, B00011111, B00001110, B00010101, B00000000, B00000000, B00000000},

 26      {B00000000, B00000000, B00000100, B00000100, B00011111, B00000100, B00000100, B00000000},

 27      {B00000000, B00000000, B00000000, B00000000, B00000000, B00000110, B00000100, B00001000},

 28      {B00000000, B00000000, B00000000, B00000000, B00001110, B00000000, B00000000, B00000000},

 29      {B00000000, B00000000, B00000000, B00000000, B00000000, B00000000, B00000000, B00000100},

 30      {B00000001, B00000010, B00000010, B00000100, B00000100, B00001000, B00001000, B00010000},

 31      {B00001110, B00010001, B00010011, B00010001, B00010101, B00010001, B00010001, B00001110},

 32      {B00000100, B00001100, B00010100, B00000100, B00000100, B00000100, B00000100, B00011111},

 33      {B00001110, B00010001, B00010001, B00000010, B00000100, B00001000, B00010000, B00011111},

 34      {B00001110, B00010001, B00000001, B00001110, B00000001, B00000001, B00010001, B00001110},

 35      {B00010000, B00010000, B00010100, B00010100, B00011111, B00000100, B00000100, B00000100},

 36      {B00011111, B00010000, B00010000, B00011110, B00000001, B00000001, B00000001, B00011110},

 37      {B00000111, B00001000, B00010000, B00011110, B00010001, B00010001, B00010001, B00001110},

 38      {B00011111, B00000001, B00000001, B00000001, B00000010, B00000100, B00001000, B00010000},

 39      {B00001110, B00010001, B00010001, B00001110, B00010001, B00010001, B00010001, B00001110},

 40      {B00001110, B00010001, B00010001, B00001111, B00000001, B00000001, B00000001, B00000001},

 41      {B00000000, B00000100, B00000100, B00000000, B00000000, B00000100, B00000100, B00000000},

 42      {B00000000, B00000100, B00000100, B00000000, B00000000, B00000100, B00000100, B00001000},

 43      {B00000001, B00000010, B00000100, B00001000, B00001000, B00000100, B00000010, B00000001},

 44      {B00000000, B00000000, B00000000, B00011110, B00000000, B00011110, B00000000, B00000000},

 45      {B00010000, B00001000, B00000100, B00000010, B00000010, B00000100, B00001000, B00010000},

 46      {B00001110, B00010001, B00010001, B00000010, B00000100, B00000100, B00000000, B00000100},

 47      {B00001110, B00010001, B00010001, B00010101, B00010101, B00010001, B00010001, B00011110},

 48      {B00001110, B00010001, B00010001, B00010001, B00011111, B00010001, B00010001, B00010001},

 49      {B00011110, B00010001, B00010001, B00011110, B00010001, B00010001, B00010001, B00011110},

 50      {B00000111, B00001000, B00010000, B00010000, B00010000, B00010000, B00001000, B00000111},

 51      {B00011100, B00010010, B00010001, B00010001, B00010001, B00010001, B00010010, B00011100},

 52      {B00011111, B00010000, B00010000, B00011110, B00010000, B00010000, B00010000, B00011111},

 53      {B00011111, B00010000, B00010000, B00011110, B00010000, B00010000, B00010000, B00010000},

 54      {B00001110, B00010001, B00010000, B00010000, B00010111, B00010001, B00010001, B00001110},

 55      {B00010001, B00010001, B00010001, B00011111, B00010001, B00010001, B00010001, B00010001},

 56      {B00011111, B00000100, B00000100, B00000100, B00000100, B00000100, B00000100, B00011111},

 57      {B00011111, B00000100, B00000100, B00000100, B00000100, B00000100, B00010100, B00001000},

 58      {B00010001, B00010010, B00010100, B00011000, B00010100, B00010010, B00010001, B00010001},

 59      {B00010000, B00010000, B00010000, B00010000, B00010000, B00010000, B00010000, B00011111},

 60      {B00010001, B00011011, B00011111, B00010101, B00010001, B00010001, B00010001, B00010001},

 61      {B00010001, B00011001, B00011001, B00010101, B00010101, B00010011, B00010011, B00010001},

 62      {B00001110, B00010001, B00010001, B00010001, B00010001, B00010001, B00010001, B00001110},

 63      {B00011110, B00010001, B00010001, B00011110, B00010000, B00010000, B00010000, B00010000},

 64      {B00001110, B00010001, B00010001, B00010001, B00010001, B00010101, B00010011, B00001111},

 65      {B00011110, B00010001, B00010001, B00011110, B00010100, B00010010, B00010001, B00010001},

 66      {B00001110, B00010001, B00010000, B00001000, B00000110, B00000001, B00010001, B00001110},

 67      {B00011111, B00000100, B00000100, B00000100, B00000100, B00000100, B00000100, B00000100},

 68      {B00010001, B00010001, B00010001, B00010001, B00010001, B00010001, B00010001, B00001110},

 69      {B00010001, B00010001, B00010001, B00010001, B00010001, B00010001, B00001010, B00000100},

 70      {B00010001, B00010001, B00010001, B00010001, B00010001, B00010101, B00010101, B00001010},

 71      {B00010001, B00010001, B00001010, B00000100, B00000100, B00001010, B00010001, B00010001},

 72      {B00010001, B00010001, B00001010, B00000100, B00000100, B00000100, B00000100, B00000100},

 73      {B00011111, B00000001, B00000010, B00000100, B00001000, B00010000, B00010000, B00011111},

 74      {B00001110, B00001000, B00001000, B00001000, B00001000, B00001000, B00001000, B00001110},

 75      {B00010000, B00001000, B00001000, B00000100, B00000100, B00000010, B00000010, B00000001},

 76      {B00001110, B00000010, B00000010, B00000010, B00000010, B00000010, B00000010, B00001110},

 77      {B00000100, B00001010, B00010001, B00000000, B00000000, B00000000, B00000000, B00000000},

 78      {B00000000, B00000000, B00000000, B00000000, B00000000, B00000000, B00000000, B00011111},

 79      {B00001000, B00000100, B00000000, B00000000, B00000000, B00000000, B00000000, B00000000},

 80      {B00000000, B00000000, B00000000, B00001100, B00010010, B00011110, B00010010, B00011111},

 81      {B00000000, B00010000, B00010000, B00010000, B00011110, B00010001, B00010001, B00011110},

 82      {B00000000, B00000000, B00000000, B00001110, B00010000, B00010000, B00010000, B00001110},

 83      {B00000000, B00000001, B00000001, B00000001, B00001111, B00010001, B00010001, B00001110},

 84      {B00000000, B00000000, B00000000, B00011100, B00010010, B00011110, B00010000, B00001110},

 85      {B00000000, B00000011, B00000100, B00000100, B00000110, B00000100, B00000100, B00000100},

 86      {B00000000, B00001110, B00001010, B00001010, B00001110, B00000010, B00000010, B00001100},

 87      {B00000000, B00010000, B00010000, B00010000, B00011100, B00010010, B00010010, B00010010},

 88      {B00000000, B00000000, B00000100, B00000000, B00000100, B00000100, B00000100, B00000100},

 89      {B00000000, B00000010, B00000000, B00000010, B00000010, B00000010, B00000010, B00001100},

 90      {B00000000, B00010000, B00010000, B00010100, B00011000, B00011000, B00010100, B00010000},

 91      {B00000000, B00010000, B00010000, B00010000, B00010000, B00010000, B00010000, B00001110},

 92      {B00000000, B00000000, B00000000, B00001010, B00010101, B00010001, B00010001, B00010001},

 93      {B00000000, B00000000, B00000000, B00010100, B00011010, B00010010, B00010010, B00010010},

 94      {B00000000, B00000000, B00000000, B00001100, B00010010, B00010010, B00010010, B00001100},

 95      {B00000000, B00001110, B00010001, B00010001, B00001110, B00010000, B00010000, B00010000},

 96      {B00000000, B00001110, B00010010, B00010010, B00001110, B00000010, B00000010, B00000001},

 97      {B00000000, B00000000, B00000000, B00001010, B00001100, B00001000, B00001000, B00001000},

 98      {B00000000, B00000000, B00001110, B00010000, B00001000, B00000100, B00000010, B00011100},

 99      {B00000000, B00010000, B00010000, B00011100, B00010000, B00010000, B00010000, B00001100},

100      {B00000000, B00000000, B00000000, B00010010, B00010010, B00010010, B00010010, B00001100},

101      {B00000000, B00000000, B00000000, B00010001, B00010001, B00010001, B00001010, B00000100},

102      {B00000000, B00000000, B00000000, B00010001, B00010001, B00010001, B00010101, B00001010},

103      {B00000000, B00000000, B00000000, B00010001, B00001010, B00000100, B00001010, B00010001},

104      {B00000000, B00000000, B00010001, B00001010, B00000100, B00001000, B00001000, B00010000},

105      {B00000000, B00000000, B00000000, B00011111, B00000010, B00000100, B00001000, B00011111},

106      {B00000010, B00000100, B00000100, B00000100, B00001000, B00000100, B00000100, B00000010},

107      {B00000100, B00000100, B00000100, B00000100, B00000100, B00000100, B00000100, B00000100},

108      {B00001000, B00000100, B00000100, B00000100, B00000010, B00000100, B00000100, B00001000},

109      {B00000000, B00011001, B00100110, B00000000, B00000000, B00000000, B00000000, B00000000}

110  };

111 

112  void clearDisplay();

113  void initMAX7219();

114  void intensity(int intensity);

115  void writeData(byte MSB, byte LSB);

116  void scroll(char myString[], int speed);

117  void screenUpdate();

118 

119  void setup()

120  {

121      initMAX7219();

122      Timer1.initialize(10000);

123      Timer1.attachInterrupt(screenUpdate);

124  }

125  void loop()

126  {

127      clearDisplay(); // Limpa a tela

128      scroll(" Mensagem 1 ", 100);

129      scroll(" Mensagem 2 ", 150);

130      scroll(" Mensagem 3 ", 200);

131 

132  }

133 

134 

135 

136  void clearDisplay()

137  {

138      for (byte x=0; x<8; x++)

139      {

140          buffer[x] = B00000000;

141      }

142      screenUpdate();

143  }

144 

145 

146  void initMAX7219()

147  {

148      pinMode(DataPin, OUTPUT);

149      pinMode(CSPin, OUTPUT);

150      pinMode(ClockPin, OUTPUT);

151      clearDisplay();

152      writeData(B00001011, B00000111);

153      writeData(B00001001, B00000000);

154      writeData(B00001100, B00000001);

155      intensity(15);

156  }

157 

158 

159  void intensity(int intensity)

160  {

161 

162      writeData(B00001010, intensity); // B00001010 é o Registrador de Intensidade (Intensity Register)

163 

164  }

165 

166 

167  void writeData(byte MSB, byte LSB)

168  {

169      byte mask; //  Utilizado como uma máscara de bits

170 

171      digitalWrite(CSPin, LOW);

172 

173      for (mask = B10000000; mask > 0; mask >>= 1)

174      {

175          digitalWrite(ClockPin, LOW);

176 

177          if (MSB & mask)

178          {

179              digitalWrite(DataPin,HIGH);

180          }

181          else  // se o E bit a bit for falso

182          {

183              digitalWrite(DataPin,LOW);

184          }

185 

186          digitalWrite(ClockPin, HIGH);

187      }

188 

189      for (mask = B10000000; mask>0; mask >>= 1)

190      {

191          digitalWrite(ClockPin, LOW);

192          if (LSB & mask)

193          {

194              digitalWrite(DataPin,HIGH);

195          }

196          else // se o E bit a bit for falso

197          {

198              digitalWrite(DataPin,LOW);

199          }

200          digitalWrite(ClockPin, HIGH);

201      }

202 

203 

204      digitalWrite(CSPin, HIGH); // trava os dados

205      digitalWrite(ClockPin, LOW);

206  }

207 

208  void scroll(char myString[], int speed)

209  {

210 

211      byte firstChrRow, secondChrRow;

212      byte ledOutput;

213      byte chrPointer = 0;

214      byte Char1, Char2;

215      byte scrollBit = 0;

216      byte strLength = 0;

217      unsigned long time;

218      unsigned long counter;

219 

220      while (myString[strLength])

221      {

222          strLength++;

223      }

224 

225      counter = millis();

226 

227      while (chrPointer < (strLength-1))

228      {

229          time = millis();

230 

231          if (time > (counter + speed))

232          {

233              Char1 = myString[chrPointer];

234              Char2 = myString[chrPointer+1];

235 

236              for (byte y= 0; y<8; y++)

237              {

238                  firstChrRow = pgm_read_byte(&font[Char1 - 32][y]);

239 

240                  secondChrRow = (pgm_read_byte(&font[Char2 - 32][y])) << 1;

241 

242                  ledOutput = (firstChrRow << scrollBit) | (secondChrRow >> (8 - scrollBit) );

243                  buffer[y] = ledOutput; // Carrega esse padrão de bits na linha apropriada do buffer de tela.

244 

245              }

246 

247              scrollBit++;

248 

249              if (scrollBit > 6)

250              {

251                  scrollBit = 0;

252                  chrPointer++;

253              }

254              counter = millis();

255          }

256      }

257  }

258 

259  void screenUpdate()

260  {

261 

262      for (byte row = 0; row < 8; row++)

263      {

264          writeData(row+1, buffer[row]);

265      }

266  }

267 

Após carregado o código, observa-se três mensagens rolando com velocidades distintas(Mensagem 1, Mensagen 2 e Mensagem 3).

Ou se preferir um código alternativo, o qual permite a entrada da velocidade, intensidade de brilho e texto pelo Monitor Serial.