1 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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2 | ;; ;;
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3 | ;; information ;;
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4 | ;; ;;
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5 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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6 | ;;
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7 | ;; This code is used for picoblaze to initialize a LCD and to write on it.
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8 | ;; It is tested on a Spartan 3E starter kit. The LCD data and command port is
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9 | ;; connected to picoblaze port 0x10:
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10 | ;;
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11 | ;; case port_id is
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12 | ;; when x"10" => lcd_output_data <= out_port(7 downto 4);
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13 | ;; lcd_drive <= out_port(3);
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14 | ;; Lcd_rs <= out_port(2);
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15 | ;; Lcd_e <= out_port(0);
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16 | ;;
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17 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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18 | ;; ;;
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19 | ;; header ;;
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20 | ;; ;;
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21 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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22 |
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23 | ;
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24 | ; output ports
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25 | CONSTANT LCD_PORT, 10
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26 |
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27 | ;
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28 | ; constants
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29 | CONSTANT DELAY_1US_CONSTANT, 0B
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30 |
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31 | ;
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32 | ; bitfields
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33 | CONSTANT LCD_E, 01
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34 | CONSTANT LCD_DRIVE, 08
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35 |
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36 | ;
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37 | ; adresses in scratchpad RAM
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38 | CONSTANT STRING_RAM, 22 ; 22-2B - string for comand
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39 |
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40 | ;
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41 | ; registers
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42 | NAMEREG s0, US_REG ; wait registers
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43 | NAMEREG s1, 40US_REG ;
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44 | NAMEREG s2, MS_REG ;
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45 | NAMEREG s3, 20MS_REG ;
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46 | NAMEREG s4, LCD_INST_REG ; LCD registers
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47 | NAMEREG s5, LCD_DATA_REG ;
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48 | NAMEREG s6, LCD_ROW_COUNTER ;
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49 |
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50 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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51 | ;; ;;
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52 | ;; LCD control functions ;;
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53 | ;; ;;
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54 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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55 |
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56 | lcd_init:
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57 | CALL delay_20ms ; wait more that 15ms for display to be ready
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58 | LOAD LCD_INST_REG, 30
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59 | CALL lcd_write_inst4 ; send '3'
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60 | CALL delay_20ms ; wait >4.1ms
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61 | CALL lcd_write_inst4 ; send '3'
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62 | CALL delay_1ms ; wait >100us
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63 | CALL lcd_write_inst4 ; send '3'
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64 | CALL delay_40us ; wait >40us
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65 | LOAD LCD_INST_REG, 20
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66 | CALL lcd_write_inst4 ; send '2'
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67 | CALL delay_40us ; wait >40us
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68 | LOAD LCD_DATA_REG, 28 ; function set
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69 | CALL lcd_write_inst8
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70 | LOAD LCD_DATA_REG, 06 ; entry mode
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71 | CALL lcd_write_inst8
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72 | LOAD LCD_DATA_REG, 0C ; display control
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73 | CALL lcd_write_inst8
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74 | LOAD LCD_ROW_COUNTER, 10 ; 16 chars per line
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75 | lcd_clear:
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76 | LOAD LCD_DATA_REG, 01 ; display clear
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77 | CALL lcd_write_inst8
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78 | CALL delay_1ms ; wait >1.64ms for display to clear
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79 | CALL delay_1ms
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80 | RETURN
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81 |
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82 | lcd_pulse_e:
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83 | XOR LCD_INST_REG, LCD_E
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84 | OUTPUT LCD_INST_REG, LCD_PORT
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85 | CALL wait_1us
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86 | XOR LCD_INST_REG, LCD_E
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87 | OUTPUT LCD_INST_REG, LCD_PORT
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88 | RETURN
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89 |
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90 | lcd_write_inst4:
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91 | AND LCD_INST_REG, F8 ; RS=0, E=0, master=1
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92 | OUTPUT LCD_INST_REG, LCD_PORT
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93 | CALL lcd_pulse_e
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94 | RETURN
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95 |
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96 | lcd_write_inst8:
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97 | LOAD LCD_INST_REG, LCD_DATA_REG
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98 | AND LCD_INST_REG, F0 ; master=0 RS=0 instruction, E=0
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99 | OR LCD_INST_REG, LCD_DRIVE ; master=1
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100 | CALL lcd_write_inst4 ; write upper nibble
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101 | CALL delay_1us
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102 | LOAD LCD_INST_REG, LCD_DATA_REG ; select lower nibble with
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103 | SL1 LCD_INST_REG ; master=1
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104 | SL0 LCD_INST_REG ; RS=0
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105 | SL0 LCD_INST_REG
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106 | SL0 LCD_INST_REG ; E=0
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107 | CALL lcd_write_inst4 ; write lower nibble
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108 | CALL delay_40us ; wait >40us
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109 | LOAD LCD_INST_REG, F0 ; master=0 RS=0 instruction, RW=0 write, E=0
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110 | OUTPUT LCD_INST_REG, LCD_PORT ; release master enable
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111 | RETURN
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112 |
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113 | lcd_cursor_home:
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114 | LOAD LCD_DATA_REG, 80
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115 | CALL lcd_write_inst8
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116 | LOAD LCD_ROW_COUNTER, 10
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117 | RETURN
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118 |
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119 | lcd_write_data:
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120 | LOAD LCD_INST_REG, LCD_DATA_REG
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121 | AND LCD_INST_REG, F0 ; master=0, RS=0 Instruction, E=0
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122 | OR LCD_INST_REG, 0C ; master=1, RS=1 Data, E=0
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123 | OUTPUT LCD_INST_REG, LCD_PORT ; set up RS and RW >40ns before enable pulse
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124 | CALL lcd_pulse_e
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125 | CALL delay_1us ; wait >1us
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126 | LOAD LCD_INST_REG, LCD_DATA_REG ; select higher nibble with
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127 | SL1 LCD_INST_REG ; master=1
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128 | SL1 LCD_INST_REG ; RS=1 Data
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129 | SL0 LCD_INST_REG ; RW=0 Write
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130 | SL0 LCD_INST_REG ; E=0
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131 | OUTPUT LCD_INST_REG, LCD_PORT ; set up RS and RW >40ns before enable pulse
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132 | CALL lcd_pulse_e ; write lower nibble
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133 | CALL delay_40us ; wait >40us
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134 | LOAD LCD_INST_REG, F0 ; master=0, RS=0 Instruction, E=0
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135 | OUTPUT LCD_INST_REG, LCD_PORT ; release master enable
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136 | SUB LCD_ROW_COUNTER, 01 ; if eol => cursor home
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137 | CALL Z, lcd_cursor_home
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138 | RETURN
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139 |
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140 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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141 | ;; ;;
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142 | ;; delay functions ;;
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143 | ;; ;;
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144 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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145 |
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146 | delay_1us:
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147 | LOAD US_REG, DELAY_1US_CONSTANT
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148 | wait_1us: SUB US_REG, 01
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149 | JUMP NZ, wait_1us
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150 | RETURN
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151 |
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152 | delay_40us:
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153 | LOAD 40US_REG, 28 ; 40 x 1us = 40us
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154 | wait_40us:CALL delay_1us
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155 | SUB 40US_REG, 01
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156 | JUMP NZ, wait_40us
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157 | RETURN
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158 |
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159 | delay_1ms:
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160 | LOAD MS_REG, 19 ; 25 x 40us = 1ms
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161 | wait_1ms: CALL delay_40us
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162 | SUB MS_REG, 01
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163 | JUMP NZ, wait_1ms
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164 | RETURN
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165 |
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166 | delay_20ms:
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167 | LOAD 20MS_REG, 14 ; 20 x 1ms = 20ms
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168 | wait_20ms:CALL delay_1ms
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169 | SUB 20MS_REG, 01
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170 | JUMP NZ, wait_20ms
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171 | RETURN
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