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NexGen: CDU Pinlite Displays: Final Word !! REDACTED!!!!

phoenixcomm

imageSTATEMENT:  I have a problem refreshing, the  20 odd displays in less than 1/4 second each, which would let them seem that there all bright, but they will be dim, to begin with. So multiplexing is now out for the 7 segment displays, but I still will multiplex the four 16 segment displays.

SOLUTION: I found an IC that handles eight 7-segment displays and it has a built-in SPI interface. The device is a MAX-7221 which will give me a solution for my problem.

As you can see in the block diagram this device has separate segment and digit drivers.

image

Arduino Mega
SCLK MOSI MISO CS
52 51 50
MAX-7211

CLK

(13)

DIN
(1)
N.A		 LOAD
12		 SC-0 (49

SC-1 (48)
CS-2 (47)
Table I
Arduino 3-bit Decoder Pins
48 47 46
Arduino Alpha Drive Pins
45 44 43 42 41
40 39 38 37 36
35 34 33 32 31
30 - - - -
Table II

 

As shown in Table I  the pins between the Arduino Mega and the MAX-7221. You will please notice that the MAX-7221 does not require MISO, and as it is ONLY a SLAVE.  You will also notice the change in the Pin Definitions promulgated by the Open Source Hardware Association.

As shown in Table II the pins between the Arduino Mega and the four 16-segment displays.  Pins 46, 47, 48 are the output to the row select which is accomplished by a BCD to Decimal

image
image

To drive this device is really quite simple, gee I wish I had some bi-polar PROMs image So I will have to do this the hard way. First I have to map the display to a letter. But the web to the rescue. there is a 16-segment font for your CRT etc.  So I still have a lot of work to do.

Letter ASCII Index A B C D E F G H I J K L M N O P Letter ASCII Index A B C D E F G H I J K L M N O P
A 41 11 x x x x x x x x S 53 29 x x x x x x
B 42 12 x x x x x x x x x T 54 30 x x x x
C 43 13 x x x x x x U 55 31 x x x x x x
D 44 14 x x x x x x V 56 32 x x x x
E 45 15 x x x x x x x x W 57 33 x x x x x x
F 46 16 x x x x x x X 58 34 x x x x
G 47 17 x x x x x x x x Y 59 35 x x x x x
H 48 18 x x x x x x Z 5A 36 x x x x x x
I 49 19 x x x x x x 0 30 0 x x x x x x x x x x
J 4A 20 x x x x x 1 31 1 x x
K 4B 21 x x x x x x x 2 32 2 x x x x x x x x
L 4C 22 x x x x 3 33 3 x x x x x x x x
M 4D 23 x x x x x x 4 34 4 x x x x x
N 4E 24 x x x x x x 5 35 5 x x x x x x x x
O 4F 25 x x x x x x x x 6 36 6 x x x x x x x x
P 50 26 x x x x x x x 7 37 7 x x x x
Q 51 27 x x x x x x x x x 8 38 8 x x x x x x x x x x
R 52 28 x x x x x x x x 9 39 9 x x x x x x x x x
Table III

typedef struct {

    int  offSet;

    int  hexChar;

    char letter;

    int  segments[16]; }  record_type ARRAY;

 

ARRAY[] ={{11, 31, 'A',{1,1,1,1,1,1,1,1,0,0,1,0,0,0,1,0}}, etc. };

 

void displayLetter ( char displayChar ) {

 

      for nt count = 0; count < 29; count++ ) {

          If  displayChar == ARRAY.letter; ) {

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  // A

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  // B

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  // C

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  // D

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  // E

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  // F

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  // G

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  // H

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  //  I

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  // J

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  // K

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count];);  // L

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  // M

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  //  N

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  //  O

                digitalWrite (ARRAY.segmentName[count], ARRAY.segments[count] );  //  P

              break; }}
Table IV

You will notice in table III  that I use an 'x' for TRUE or 1 and 'blank' for FALSE or 0.  Also, note my numbers start a 1 and then skips number 10. If you will notice I have 3 columns Letter, ASCII, and Index. I will use the Index column for my array but an array will not really work so you need a structure, see table IV the blue box on the right.

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