8x8 LED matrix "smooth" horizontal scrolling text - what's the math?

[CuriousOne]

Or to have character data in eeprom, and also have a "display buffer" array which is read and refreshed consistently, but character data being written to it with changing offset.
I did in the similar way for TM1629A, but I'm using 8 x 16 segment LED displays, so my code will have little use here.

[flotulopex]

Si, here is my solution.

To avoid any extra need of data conversion (from columns to lines...), I decided to use the MAX7219 ARDUINO module with the inter-connecting pins positionned vertically.



Doing so, instead of displaying horizontal lines from bottom to top, it now displays vertical lines from right to left without any need of "too complicated math" for me to convert data from horizontal to vertical.

Currently I have the need for one module. Of course, if I would need to chain several modules, I then would need 10cm 5x flat cables to connect the modules to each other.

Thanks a lot for the help

'======= FUSES ====================================================================================
' PIC 16F690

' Internal oscillator  (activate OSCCON register)
@ __config _FCMEN_OFF &_IESO_OFF &_CPD_OFF &_WDT_OFF &_INTRC_OSC_NOCLKOUT &_BOR_OFF &_CP_OFF &_PWRTE_OFF &_MCLRE_OFF

@ ERRORLEVEL -306
@ ERRORLEVEL -202

' ====== REGISTERS ==================================================================================
'             76543210
OPTION_REG = %10000000 'PORT A&B Pull-Ups disabled (look WPUA & WPUB)
OSCCON     = %01110000 'Internal RC set to 8Mhz
ANSEL      = %00000000 'Analog inputs Channels 0 to 7
ANSELH     = %00000000 'Analog inputs Channels 8 to 11
WPUA       = %00000000 'Weak pull-ups
WPUB       = %00000000 'Weak pull-ups
ADCON0     = %00000000 'A/D Module (OFF)
CM1CON0    = %00000000 'Comparator1 Module (OFF)
CM2CON0    = %00000000 'Comparator2 Module (OFF)
INTCON     = %00000000 'INTerrupts CONtrol
TRISA      = %00000000 'Set Input/Output (0 to 5)
PORTA      = %00000000 'Ports High/Low (0 to 5)
TRISB      = %00000000 'Set Input/Output (4 to 7)
PORTB      = %00000000 'Ports High/Low (4 to 7)
TRISC      = %00000000 'Set Input/Output (0 to 7)
PORTC      = %00000000 'Ports High/Low (0 to 7)
                                
' ====== DEFINES ==================================================================================
DEFINE OSC 8
DEFINE NO_CLRWDT 1
  
' ====== VARIABLES ================================================================================
Addr_Reg    VAR BYTE    ' 7219's address register (1..8)
Data_Reg    VAR BYTE    ' 7219's data register
ScrollSpeed VAR WORD    ' pause time between frames (8 lines = 1 frame)
Line        VAR BYTE    ' line number of a frame - from 0 (bottom line) to 7 (top line)
Start       VAR BYTE    ' starting position in LOOKUP

CLK         VAR PORTB.4 ' connected to module's CLK
LOAD        VAR PORTB.5 ' connected to module's CS
DAT         VAR PORTB.6 ' connected to module's DIN

' ====== INITIALIZE ===============================================================================
LOW CLK
LOW DAT
LOW LOAD
ScrollSpeed = 80

' ====== MAX7219 SETUP ============================================================================
Addr_Reg = $09 : Data_Reg = $00 : GOSUB MaxWrite ' DECODE-MODE (= BCD), NO DECODE
Addr_Reg = $0A : Data_Reg = $00 : GOSUB MaxWrite ' LEDS INTENSITY MIN=0, MAX=F
Addr_Reg = $0B : Data_Reg = $07 : GOSUB MaxWrite ' NUMBER OF DISPLAYED LINES (0=bottom .. 7=top)
Addr_Reg = $0C : Data_Reg = $01 : GOSUB MaxWrite ' SHUTDOWN=0, NORMAL OPERATION=1
Addr_Reg = $0F : Data_Reg = $00 : GOSUB MaxWrite ' DISPLAY-TEST (0=OFF, 1=ON)
               
' ====== PROGRAM ==================================================================================
SCROLL:
    FOR Start = 0 TO 80 ' number of data in the LOOKUP - 8
        FOR Addr_Reg = 1 TO 8
            Line = (Addr_Reg - 1) + Start
            GOSUB PICBasic
            GOSUB MAXWRITE
        NEXT
        PAUSE ScrollSpeed
    NEXT
    GOTO SCROLL

END

' ====== SUBROUTINES ==============================================================================
MaxWrite:
    SHIFTOUT DAT,CLK,1,[Addr_Reg,Data_Reg] ' send the data to the MAX7219
    PULSOUT LOAD,1 ' push the data into the MAX7219
    RETURN

' ====== DISPLAY DATA =============================================================================
' 90 degrees anticlockwise rotated characters for use with vertically positionned MAX7219 ARDUINO module

'Right_V_Line:
'LOOKUP Line, [  0,  0,  0,  0,  0,  0,  0,255,  0,  0,  0,  0,  0,  0,  0,  0],Data_Reg

PICBasic:
LOOKUP Line, [  0,  0,  0,  0,  0,  0,  0,  0,_
                0,254,254, 34, 34, 62, 28,  0,_          'P
                0,  0,130,254,254,130,  0,  0,_          'I
                0,124,254,130,130,198, 68,  0,_          'C
                0,  0,  0,  0,  0,  0,  0,  0,_          
                0,254,254,146,146,254,108,  0,_          'B
                0, 64,232,168,168,248,240,  0,_          'a
                0,144,168,168,168,168, 72,  0,_          's
                0,  0,128,244,244,128,  0,  0,_          'i
                0,112,248,136,136,216, 80,  0,_          'c                
                0,  0,  0,  0,  0,  0,  0,  0],Data_Reg
    RETURN