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33
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1 |
;; LED Matrix driver
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2 |
;;
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3 |
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4 |
.set MATRIX_DDR = DDRB
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5 |
.set MATRIX_PORT = PORTB
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6 |
.set MATRIX_OE = PORTB1 ; Output Enable, active low, externally pulled high
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7 |
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8 |
.dseg
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9 |
.set MATRIX_COLS = 8 ; number of columns
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10 |
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11 |
matrix_colbit: .byte 1 ; column bit
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12 |
matrix_rowbuf: .byte MATRIX_COLS ; row bitmask by column
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13 |
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14 |
.cseg
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15 |
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16 |
;; Normalize the outputs, enable the matrix, an set up buffers
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17 |
Matrix_Init:
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18 |
; Setup ENable port
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19 |
sbi MATRIX_PORT, MATRIX_OE ; high -> disabled
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20 |
sbi MATRIX_DDR, MATRIX_OE ; out
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21 |
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22 |
; blank hardware
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23 |
ldi r16, 0
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24 |
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25 |
sts spi_outbuf + 0, r16 ; column sinks
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26 |
sts spi_outbuf + 1, r16 ; row drivers
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27 |
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28 |
; write out
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29 |
rcall SPI_SendRecv
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30 |
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31 |
; enable
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32 |
cbi MATRIX_PORT, MATRIX_OE ; low -> enabled
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33 |
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34 |
; init buffers
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35 |
ldi r16, 0b1
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36 |
sts matrix_colbit, r16
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37 |
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38 |
ldi r16, 0
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39 |
ldi r17, MATRIX_COLS
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40 |
ldi YL, low(matrix_rowbuf)
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41 |
ldi YH, high(matrix_rowbuf)
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42 |
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43 |
m_init_mzero:
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44 |
st Y+, r16
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45 |
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46 |
; loop until zero
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47 |
dec r17
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48 |
brne m_init_mzero
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49 |
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50 |
; Use Timer0, 32k cycles -> 500Hz scan rate
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51 |
ldi r16, 32
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52 |
rcall Timer0_Start
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53 |
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54 |
; done
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55 |
ret
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56 |
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57 |
;; Scan the next column
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58 |
;; Interrupt-driven
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59 |
Matrix_ScanCol:
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60 |
; Column bit
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61 |
; load
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62 |
lds r16, matrix_colbit
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63 |
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64 |
; start packet
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65 |
cbi SPI_PORT, SPI_SS
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66 |
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67 |
; output
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68 |
out SPDR, r16
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69 |
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70 |
; Compute col index
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ldi r17, 0
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72 |
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m_sc_colidx:
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; shift
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75 |
lsr r16
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76 |
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77 |
; done if we shifted the bit out
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78 |
brcs m_sc_row
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79 |
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80 |
; count shifts
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81 |
inc r17
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82 |
rjmp m_sc_colidx
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83 |
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m_sc_row:
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85 |
; Row mask
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86 |
; base
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ldi XL, low(matrix_rowbuf)
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88 |
ldi XH, high(matrix_rowbuf)
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89 |
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90 |
; offset
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91 |
ldi r18, 0
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92 |
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93 |
add XL, r17
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94 |
adc XH, r18
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95 |
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96 |
; load
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97 |
ld r16, X
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98 |
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99 |
; output
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100 |
rcall SPI_Wait
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101 |
out SPDR, r16
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102 |
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103 |
; Update col bit
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104 |
lds r16, matrix_colbit
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105 |
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106 |
; shift left
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107 |
lsl r16
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108 |
brcc m_sc_colout
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109 |
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110 |
; overflow, take bit from C
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111 |
rol r16
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112 |
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113 |
m_sc_colout:
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114 |
; store
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115 |
sts matrix_colbit, r16
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116 |
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117 |
; End of packet
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118 |
rcall SPI_Wait
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119 |
sbi SPI_PORT, SPI_SS
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120 |
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121 |
; Done
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122 |
ret
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123 |
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124 |
;; Scan the matrix once in one go
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125 |
Matrix_ScanFull:
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126 |
; Row index
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127 |
ldi ZL, low(matrix_rowbuf)
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128 |
ldi ZH, high(matrix_rowbuf)
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129 |
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130 |
; Column bit
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131 |
ldi r25, 0
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132 |
sec ; set C
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133 |
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134 |
m_pulse_col:
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135 |
; rotate bit left from C
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136 |
rol r25
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137 |
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138 |
; overflow
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139 |
brcs m_pulse_end
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140 |
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141 |
; store in output buffer
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142 |
sts spi_outbuf + 1, r25
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143 |
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144 |
; Row mask
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145 |
ld r16, Z+
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146 |
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147 |
sts spi_outbuf + 0, r16
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148 |
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149 |
; Display
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150 |
rcall SPI_SendRecv
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151 |
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152 |
; Next column
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153 |
rjmp m_pulse_col
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154 |
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155 |
m_pulse_end:
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156 |
; Done
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157 |
ret
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158 |
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