Rotating text with PIC16F877

[StudentInNeeded]

I need some help, I'm doing an LED display controlled by a PIC16F877A. All my columns are linked together and all my rows too, so I can control independently each LED. Now, I have 28 columns by 7 rows, and I can send 1 letter, that mean 6 columns by 7 rows. But when I upgrade my two-dimensional table variable to 28(columns) and that I compile, CCS me returns an error "Data item too big".

1 Letter declaration: (Working)

[PCM programmer]

Do you need to use a byte for each led ? Why not use a bit ?
Then you can use 1/8 of the RAM for the table.

For example, look at the character font tables in this file.
They pack each character into 5 bytes.

[Spatofy]

I can't use that glcd.c because I'm doing my own display with LED. It's a matrix of 7x28 and I'm able to send a entire row of 28 at the same time, so I did a refresh procedure to show every row a little time to display a full letter. I need to use a bit for every LED.

[PCM programmer]

Since your entire data consists of 1's and 0's, you can certainly pack
the data into bytes and then unpack it before you display it. Packing
data into bytes is a standard technique used by embedded programmers
to conserve ROM space. The data is compiled in packed format, and
then you need to write a routine to unpack it at runtime.

Look at the many character generators for LCD that are available on
the net. They graphically show how the packing is done:
http://www.keokitrask.com/EDL/LCDCharacterGenerator.htm
More explanation:
http://www.rentron.com/Myke2.htm

[kamputty]

Hi all!

Look at the OLED example I have in the software area for PIC...it has the 5x7 fonts (thanks to my daughter's handy work) that does it using bits...might help, might not!

~Kam (^8*

[kamputty]

While I was thinking about it...here is the font part of the code...

int8 fonts[80][5]=
{
{ // 0
0b00111110,
0b01010001,
0b01001001,
0b01000101,
0b00111110
},
{ // 1
0b00000000,
0b01000010,
0b01111111,
0b01000000,
0b00000000
},
{ // 2
0b01000010,
0b01100001,
0b01010001,
0b01001001,
0b01000110
},
{ // 3
0b00100010,
0b01000001,
0b01001001,
0b01001001,
0b00110110
},
{ // 4
0b00011000,
0b00010100,
0b00010010,
0b01111111,
0b00010000
},
{ // 5
0b00100111,
0b01000101,
0b01000101,
0b01000101,
0b00111001
},
{ // 6
0b00111100,
0b01001010,
0b01001001,
0b01001001,
0b00110000
},
{ // 7
0b00000001,
0b01110001,
0b00001001,
0b00000101,
0b00000011
},
{ // 8
0b00110110,
0b01001001,
0b01001001,
0b01001001,
0b00110110
},
{ // 9
0b00000110,
0b01001001,
0b01001001,
0b01001001,
0b00111110
},
{ // !
0b00000000,
0b00000000,
0b01011111,
0b00000000,
0b00000000
},


and so on.

Each character is only 5 bytes...

~Kam (^8*

[StudentInNeeded]

Finally, i just change my 16f877 for an 18f452, same pinout but way more memory...