Bill
I have used these displays for a couple of years and also have made my own displays using the MAX7219. I can tell you they are sensitive at start up you need to ensure you have enough capacitance. For my home brew project I had to add a 100uf cap on the 5 volt lines. Got a lot of strange results without it' I have also included the setup I use with two chips daisey chained.
Code:
'###############################################################################
' ====================== MAX7219 SETUP ==========================
MAX_SET_UP:
for a = 0 to 3
For index = 0 to 7 ' Retrieve 8 items from table.
LookUp index,[SCAN,7,BRITE,10,DECODE,%11111111,ON_OFF,1],max_dat
ShiftOut DATA_n,CLK_n,1,[max_dat]
IF odd = 0 Then noLoad ' If odd is 1,
PulsOut LOAD_n,1 ' pulse LOAD line.
NoLoad: ' Else, don't pulse.
Next index ' Get next item from table.
next a
return
'' ===================== DISPLAY SUBROUTINE ========================
Max1:
ShiftOut DATA_n,CLK_n,1,[0,0] '
ShiftOut DATA_n,CLK_n,1,[seg,dat] ' Send the digit.
PulsOut LOAD_n,1 ' Load the display.
' Repeat for all 4 digits.
return ' Done? Return.
Max2:
ShiftOut DATA_n,CLK_n,1,[seg,dat] ' Send the digit.
ShiftOut DATA_n,CLK_n,1,[0,0]
PulsOut LOAD_n,1
return
Good luck
Dave
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