DEMO of Dot set / reset on MAX7912 matrix displays.
by AndyGadget https://cicciocb.com/forum/viewtopic.php?f=7&t=636&p=2881#p2881

Modify the content of main.bas and run it.
Annex 1.46.5 is below the hood :-)



help.txt

# Name,   Type, SubType, Offset,  Size, Flags
nvs,      data, nvs,     0x9000,  0x5000,
otadata,  data, ota,     0xe000,  0x2000,
app0,     app,  ota_0,   0x10000, 0x230000,
app1,     app,  ota_1,   0x240000,0x0C0000,
ffat,     data, fat,     0x300000,0x100000,
#spiffs,   data, spiffs,  0x301000,0xFF000,


partitions.csv

' Dot set / reset by X/Y co-ords for MAX7219 Dot Matrix Displays.
' 0,0 is top left.
' N.B. This is incompatible with Annex built-in scrolling functions.


wlog "Start"
iobuff.dim(0,8)
iobuff.dim(1,64)

SPI.CSPIN 15
SPI.SETUP 10000000
DDat$ = ""

InitDisplay

do
  x = rnd(32) : y = rnd(8) : z = rnd(2)
  Dot x,y,z
loop

end


' SUBROUTINES
' ===========

' Usage Dot(X position, Y position, on/off)
' 1 = on, 0 = off
' Origin is 0,0 at top left corner.  Bottom right is 31,7
' (Unless you invert the display, of course :¬)

sub Dot(xx,yy,sr)
  
  c1 = (xx \ 8)             ' Integer part gives disp no. (0 to 3)
  c2 = (xx mod 8)           ' gives dot offset in byte (0 to 7)
  r1 = (yy mod 8)           ' gives row  (0 to 7)
  r2 = (yy \ 4)             ' gives dot offset in byte (0 to 7)
  DPtr = (((r1*4)+c1)*4)+3 ' Position of data byte in output string
  
  newbyte = &h80 >> c2
  oldbyte = val("&H"+mid$(DDat$,DPtr,2)) ' Existing byte from output string
  
  if sr = 1 then
    newhex$ = right$("00" + hex$(newbyte OR oldbyte),2)
  else
    newhex$ = right$("00" + hex$((NOT newbyte) AND oldbyte),2)
  endif
  
  DDat$ = left$(DDat$,DPtr-1) + newhex$ + right$(DDat$,128-DPtr-1)
  UpdateDisplay
end sub

sub ClearBuff
  DDat$="01000100010001000200020002000200030003000300030004000400040004000500050005000500060006000600060007000700070007000800080008000800"
end sub

sub UpdateDisplay
  ' Dump Display Data string to SPI buffer
  for cnt = 0 to 8
    iobuff.fromhex(1,DDat$)
    SPI.WRITE_IOBUFF(1,cnt*8,8)
  next cnt
end sub

sub InitDisplay
  ' Reg &H01 - Shutdown mode - Enable displays
  cdat$ = string$(4,"0C01")
  iobuff.fromhex(0,cdat$)
  SPI.WRITE_IOBUFF(0)
  
  ' Reg &H09 - Decode mode - No decode
  cdat$ = string$(4,"0900")
  iobuff.fromhex(0,cdat$)
  SPI.WRITE_IOBUFF(0)
  
  ' Reg &H0B - Scan limit - 8 rows
  cdat$ = string$(4,"0B07")
  iobuff.fromhex(0,cdat$)
  SPI.WRITE_IOBUFF(0)
  
  ' Reg &H0A - Intensity - Range &H00 to &H0F
  Int$ = "01"
  cdat$ = string$(4,"0A" + Int$)
  iobuff.fromhex(0,cdat$)
  SPI.WRITE_IOBUFF(0)
  
  ClearBuff
  UpdateDisplay
  
end sub


'     Layout of display data string.
'     ==============================
'     Top left of first display is    0180xxxxxxxxxxxx
'     Bottom right of last display is xxxxxxxxxxxx0801
'      ----    ----    ----    ----    ----    ----    ----    ----    ----    ----    ----    ----    ----    ----    ----    ----
'Disp  D1  D2  D3  D4  D1  D2  D3  D4  D1  D2  D3  D4  D1  D2  D3  D4  D1  D2  D3  D4  D1  D2  D3  D4  D1  D2  D3  D4  D1  D2  D3  D4
'Row   R1  R1  R1  R1  R2  R2  R2  R2  R3  R3  R3  R3  R4  R4  R4  R4  R5  R5  R5  R5  R6  R6  R6  R6  R7  R7  R7  R7  R8  R8  R8  R8
'#DNum  1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32
'#DPos  1   5   9  13  17  21  25  29  33  37  41  45  49  53  57  61  65  69  73  77  81  85  89  93  97 101 105 109 113 117 121 125
'
