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




Bookmarks