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  • Author Author: phoenixcomm
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NexGen: CDU Pinlite Displays: Really the Final Word !! -- DEPRECATED

phoenixcomm

imageI took a long look at the mess that I created. And I said to myself: There has to be a better way!! A few PROMS or EPROMS would be supper, but alas I don't have a programmer anymore. image It looks like I will need a bunch of TI's PCF8575, 16-bit IO expander. The way it shakes out is that 8 should do it. 4 one for each of the four 16-segment displays, and 4 more for the 13 7-segment lamps, Now you ask how can I drive 13 lamps with four devices well I only need 4 bits which means I get 4 lamps per IO expander, I can store BCD in 4-bits, but I really only need 3-bits. each of the pins to drive a BCD to a 7-segment Decoder image drive a BCD to 7-segment Decoder, by doing

this I no longer have to worry about refresh times. I just found a new device an I2C EEPROM The EEPROM is a 24LC01 organized as 128 x 8 bits. So I can put the whole table in one IC, so for numbers 0-9 that's the first 9 words. in contrast, the alphas need more work. Remember we are dealing with bit patterns. So for each one of the alphas, I will need 16 bits for the pattern. So since I have lots of room I'm putting the high side from row 100 up, so it will take two reads and two writes 

image

ASCCI

 

 SYMBOL ROW  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 ASCCI SYMBOL ROW  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16
SEG A B C D E F G H I J K L M N O P SEG A B C D E F G H I J K L M N O P
30 0 0 1 1 1 1 1 1 1 1 53 K
31 1 1 0 0 0 0 0 0 1 1 153 K
32 2 2 54 L
33 3 3 154 L
34 4 55 M
35 5 5 155 M
36 6 6 56 N
37 7 7 156 N
38 8 8 57 O
39 9 9 1 1 0 1 1 1 1 1 157 O
41 A 10 0 0 1 1 1 1 1 1 58 P
141 A' 80 0 0 0 0 0 0 1 1 158 P P'
42 B 11 1 1 0 0 1 1 1 1 59 Q
142 B' 81 0 1 0 0 0 1 0 0 159 Q
43 C 12 60 R
143 C' 82 160 R
44 D 13 61 S
144 D' 83 161 S
45 E 14 62 T
145 E' 84 162 T
46 F 15 63 U
146 F'' 85 163 U
47 G 16 64 V
147 G' 86 164 V
48 F 17 65 W
148 F' 87 165 W
49 G 18 66 X
149 G' 88 166 X
50 H 19 67 Y 0 0 0 1 0 0 1 0
150 H' 89 167 Y 0 1 0 1 0 0 0 1
51 I 20 68 Z 1 1 0 0 1 1 0 0
151 I' 90 168 Z 1 0 0 0 1 0 0 0
52 J 21 BLANK 0 0 0 0 0 0 0 0
152 J' 91 BLANK 0 0 0 0 0 0 0 0

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