Wie sieht das aus, sollte man bei der I2C Verbindung (100kbits) nach
jedem geänderten Bit das Byte an den PCF5854 senden? Oder reicht es so
wie folgt?
LCD_PORT ist hier kein avr Port sondern lediglich ein Byte, welches aber
von Hand über I2C geschoben werden.
Hier ein kurzer Einblick.
1 | static void lcd_enable(void)
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2 | {
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3 | LCD_PORT |= (1 << LCD_EN);
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4 | lcd_sendOut(LCD_PORT);
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5 | delay_us(LCD_DELAY_ENABLE_PULSE);
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6 | LCD_PORT &= ~(1 << LCD_EN);
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7 | lcd_sendOut(LCD_PORT);
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8 | }
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9 |
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10 | static void lcd_write(unsigned char data, unsigned char rs)
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11 | {
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12 | if (rs) LCD_PORT |= (1 << LCD_RS); // Schreibe Daten
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13 | else LCD_PORT &= ~(1 << LCD_RS); // Schreibe Befehl
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14 | LCD_PORT &= ~(1 << LCD_RW);
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15 | lcd_sendOut(LCD_PORT);
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16 |
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17 | /* output high nibble first */
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18 | LCD_PORT &= ~(1 << LCD_D7);
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19 | LCD_PORT &= ~(1 << LCD_D6);
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20 | LCD_PORT &= ~(1 << LCD_D5);
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21 | LCD_PORT &= ~(1 << LCD_D4);
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22 | lcd_sendOut(LCD_PORT);
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23 |
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24 | if (data & 0x10) LCD_PORT |= (1 << LCD_D4);
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25 | if (data & 0x20) LCD_PORT |= (1 << LCD_D5);
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26 | if (data & 0x40) LCD_PORT |= (1 << LCD_D6);
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27 | if (data & 0x80) LCD_PORT |= (1 << LCD_D7);
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28 | lcd_sendOut(LCD_PORT);
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29 | lcd_enable();
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30 |
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31 | /* output low nibble */
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32 | LCD_PORT &= ~(1 << LCD_D7);
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33 | LCD_PORT &= ~(1 << LCD_D6);
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34 | LCD_PORT &= ~(1 << LCD_D5);
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35 | LCD_PORT &= ~(1 << LCD_D4);
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36 | lcd_sendOut(LCD_PORT);
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37 |
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38 | if (data & 0x01) LCD_PORT |= (1 << LCD_D4);
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39 | if (data & 0x02) LCD_PORT |= (1 << LCD_D5);
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40 | if (data & 0x04) LCD_PORT |= (1 << LCD_D6);
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41 | if (data & 0x08) LCD_PORT |= (1 << LCD_D7);
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42 | lcd_sendOut(LCD_PORT);
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43 | lcd_enable();
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44 |
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45 | /* all data pins high (inactive) */
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46 | LCD_PORT |= (1 << LCD_D4);
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47 | LCD_PORT |= (1 << LCD_D5);
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48 | LCD_PORT |= (1 << LCD_D6);
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49 | LCD_PORT |= (1 << LCD_D7);
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50 | lcd_sendOut(LCD_PORT);
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51 | }
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