1 | #include "msp430.h"
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2 |
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3 | #define LCM_DIR P2DIR
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4 | #define LCM_OUT P2OUT
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5 |
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6 | //
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7 |
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8 | #define LCM_PIN_RS BIT0 // P2.0
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9 | #define LCM_PIN_EN BIT1 // P2.1
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10 | #define LCM_PIN_D7 BIT5 // P2.5
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11 | #define LCM_PIN_D6 BIT4 // P2.4
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12 | #define LCM_PIN_D5 BIT3 // P2.3
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13 | #define LCM_PIN_D4 BIT2 // P2.2
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14 |
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15 |
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16 |
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17 | #define LCM_PIN_MASK ((LCM_PIN_RS | LCM_PIN_EN | LCM_PIN_D7 |
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18 | LCM_PIN_D6 | LCM_PIN_D5 | LCM_PIN_D4))
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19 |
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20 | #define FALSE 0
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21 | #define TRUE 1
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22 |
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23 | //
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24 | // Routine Desc:
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25 | //
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26 | // This is the function that must be called
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27 | // whenever the LCM needs to be told to
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28 | // scan it's data bus.
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29 | //
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30 | // Parameters:
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31 | //
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32 | // void.
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33 | //
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34 | // Return
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35 | //
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36 | // void.
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37 | //
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38 | void PulseLcm()
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39 | {
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40 | //
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41 | // pull EN bit low
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42 | //
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43 | LCM_OUT &= ~LCM_PIN_EN;
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44 | __delay_cycles(200);
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45 |
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46 | //
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47 | // pull EN bit high
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48 | //
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49 | LCM_OUT |= LCM_PIN_EN;
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50 | __delay_cycles(200);
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51 |
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52 | //
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53 | // pull EN bit low again
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54 | //
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55 | LCM_OUT &= (~LCM_PIN_EN);
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56 | __delay_cycles(200);
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57 | }
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58 |
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59 |
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60 |
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61 | //
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62 | // Routine Desc:
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63 | //
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64 | // Send a byte on the data bus in the 4 bit mode
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65 | // This requires sending the data in two chunks.
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66 | // The high nibble first and then the low nible
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67 | //
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68 | // Parameters:
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69 | //
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70 | // ByteToSend - the single byte to send
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71 | //
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72 | // IsData - set to TRUE if the byte is character data
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73 | // FALSE if its a command
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74 | //
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75 | // Return
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76 | //
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77 | // void.
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78 | //
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79 | void SendByte(char ByteToSend, int IsData)
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80 | {
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81 | //
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82 | // clear out all pins
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83 | //
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84 | LCM_OUT &= (~LCM_PIN_MASK);
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85 | //
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86 | // set High Nibble (HN) -
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87 | // usefulness of the identity mapping
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88 | // apparent here. We can set the
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89 | // DB7 - DB4 just by setting P1.7 - P1.4
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90 | // using a simple assignment
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91 | //
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92 | LCM_OUT |= (ByteToSend & 0x3C);
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93 |
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94 | if (IsData == TRUE)
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95 | {
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96 | LCM_OUT |= LCM_PIN_RS;
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97 | }
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98 | else
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99 | {
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100 | LCM_OUT &= ~LCM_PIN_RS;
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101 | }
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102 |
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103 | //
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104 | // we've set up the input voltages to the LCM.
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105 | // Now tell it to read them.
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106 | //
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107 | PulseLcm();
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108 | //
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109 | // set Low Nibble (LN) -
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110 | // usefulness of the identity mapping
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111 | // apparent here. We can set the
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112 | // DB7 - DB4 just by setting P1.7 - P1.4
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113 | // using a simple assignment
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114 | //
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115 | LCM_OUT &= (~LCM_PIN_MASK);
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116 | LCM_OUT |= ((ByteToSend & 0x0F) << 4);
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117 |
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118 | if (IsData == TRUE)
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119 | {
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120 | LCM_OUT |= LCM_PIN_RS;
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121 | }
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122 | else
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123 | {
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124 | LCM_OUT &= ~LCM_PIN_RS;
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125 | }
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126 |
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127 | //
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128 | // we've set up the input voltages to the LCM.
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129 | // Now tell it to read them.
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130 | //
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131 | PulseLcm();
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132 | }
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133 |
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134 |
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135 | //
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136 | // Routine Desc:
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137 | //
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138 | // Set the position of the cursor on the screen
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139 | //
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140 | // Parameters:
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141 | //
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142 | // Row - zero based row number
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143 | //
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144 | // Col - zero based col number
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145 | //
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146 | // Return
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147 | //
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148 | // void.
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149 | //
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150 | void LcmSetCursorPosition(char Row, char Col)
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151 | {
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152 | char address;
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153 |
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154 | //
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155 | // construct address from (Row, Col) pair
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156 | //
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157 | if (Row == 0)
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158 | {
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159 | address = 0;
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160 | }
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161 | else
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162 | {
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163 | address = 0x40;
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164 | }
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165 |
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166 | address |= Col;
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167 |
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168 | SendByte(0x80 | address, FALSE);
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169 | }
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170 |
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171 |
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172 | //
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173 | // Routine Desc:
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174 | //
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175 | // Clear the screen data and return the
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176 | // cursor to home position
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177 | //
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178 | // Parameters:
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179 | //
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180 | // void.
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181 | //
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182 | // Return
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183 | //
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184 | // void.
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185 | //
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186 | void ClearLcmScreen()
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187 | {
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188 | //
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189 | // Clear display, return home
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190 | //
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191 | SendByte(0x01, FALSE);
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192 | SendByte(0x02, FALSE);
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193 | }
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194 |
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195 |
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196 | //
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197 | // Routine Desc:
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198 | //
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199 | // Initialize the LCM after power-up.
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200 | //
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201 | // Note: This routine must not be called twice on the
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202 | // LCM. This is not so uncommon when the power
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203 | // for the MCU and LCM are separate.
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204 | //
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205 | // Parameters:
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206 | //
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207 | // void.
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208 | //
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209 | // Return
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210 | //
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211 | // void.
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212 | //
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213 | void InitializeLcm(void)
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214 | {
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215 | //
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216 | // set the MSP pin configurations
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217 | // and bring them to low
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218 | //
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219 | LCM_DIR |= LCM_PIN_MASK;
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220 | LCM_OUT &= ~(LCM_PIN_MASK);
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221 |
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222 |
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223 | //
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224 | // wait for the LCM to warm up and reach
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225 | // active regions. Remember MSPs can power
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226 | // up much faster than the LCM.
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227 | //
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228 | __delay_cycles(100000);
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229 |
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230 |
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231 | //
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232 | // initialize the LCM module
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233 | //
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234 | // 1. Set 4-bit input
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235 | //
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236 | LCM_OUT &= ~LCM_PIN_RS;
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237 | LCM_OUT &= ~LCM_PIN_EN;
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238 |
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239 | LCM_OUT = 0x20;
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240 | PulseLcm();
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241 |
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242 | //
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243 | // set 4-bit input - second time.
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244 | // (as reqd by the spec.)
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245 | //
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246 | SendByte(0x28, FALSE);
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247 |
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248 | //
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249 | // 2. Display on, cursor on, blink cursor
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250 | //
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251 | SendByte(0x0E, FALSE);
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252 |
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253 | //
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254 | // 3. Cursor move auto-increment
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255 | //
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256 | SendByte(0x06, FALSE);
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257 | }
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258 |
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259 |
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260 | //
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261 | // Routine Desc
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262 | //
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263 | // Print a string of characters to the screen
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264 | //
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265 | // Parameters:
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266 | //
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267 | // Text - null terminated string of chars
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268 | //
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269 | // Returns
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270 | //
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271 | // void.
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272 | //
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273 | void PrintStr(char *Text)
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274 | {
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275 | char *c;
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276 |
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277 | c = Text;
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278 |
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279 | while ((c != 0) && (*c != 0))
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280 | {
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281 | SendByte(*c, TRUE);
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282 | c++;
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283 | }
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284 | }
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285 |
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286 |
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287 | //
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288 | // Routine Desc
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289 | //
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290 | // main entry point to the sketch
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291 | //
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292 | // Parameters
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293 | //
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294 | // void.
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295 | //
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296 | // Returns
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297 | //
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298 | // void.
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299 | //
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300 | void main(void)
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301 | {
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302 | WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer
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303 |
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304 | InitializeLcm();
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305 |
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306 | ClearLcmScreen();
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307 |
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308 | PrintStr("Hello World!");
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309 |
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310 | while (1)
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311 | {
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312 | __delay_cycles(1000);
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313 | }
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314 |
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315 | }
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