MAX7219 & 7 Seg Display

Xeus · Joined: 28 Jan 2005 Posts: 4

Hi

The Problem:

I'd like to build an counter with an ATmega8, MAX 7219 and a 3 Digit 7 Segment Display.
The hardware is already running, and I m able to show a single-figure number.

for examle:
0 to 9

But how does it work, to show a two figure number like 10,11...
How does it work to jump in the next digit??

Thanks,

xeus

SORRY FOR MY POOR ENGLISH Crying or Very sad

Duval JP · Joined: 22 Jun 2004 Posts: 1161 Location: France

Hi,
Well, how I do , maybe another method exists,
for a chrono, I created 2 arrays of data:
where the data was 0 to nine (values sent to the ports to light bar)
'--------[restaure data]----------------------------
'seconde
Restore Seconde
For J = 1 To 10
Read Tabseconde(j)
Next
'minute
Restore tenseconde
For J = 1 To 10
Read Tabtenseconde(j)
Next

'write at the end of program
'that is my data you must write ours !
----[data]--------------------------------------------------------
Seconde:
Data 72 , 115 , 107 , 108 , 47 , 62 , 73 , 127 , 109 , 95

tenseconde:
Data 34 , 155 , 186 , 106 , 248 , 233 , 50 , 251 , 122 , 243

then I compare my total of seconde against timer
and I increment my total of "10seconde"
if seconde =10 then
seconde=0
tenseconde=tenseconde+1
endif
Portb = Not Tabseconde(seconde)
Portd = Not Tabtenseconde(tenseconde)

For 3 you add one....
I hope you understand my frenchy english !
bon courage
JP

Xeus · Joined: 28 Jan 2005 Posts: 4

does it already in the one wire mode work?
the communication between the mc and the max7219 needs just one port of the mc

thanks for your help

xeus

Twenty · Joined: 30 Nov 2004 Posts: 50 Location: Sydney

Xeus,

I'm using the max7219 in one of my projects. The max7219 requires you to send a number 0-9 to a specific digit. You cannot send a number bigger than 9. What I do is to first convert the number (0-99) to bcd and then extract each didgit from it by using the AND operator.

Let NUMBER be the number to be displayed and
NUMBER_BCD the BCD version of it

Use var1=BCD_NUMBER AND &B00001111 for the first digit and
use var2=BCD_NUMBER AND &B11110000 for the second digit. Remember to shift var2 four places to the right before sending it to the max7219

Here is an extract of my code that works:

Dim Dis as integer

Dis = Makebcd(dis)
Dig_val1 = Dis And &B00001111 : W = Makeint(dig_val1 , 1) : Call Show(w) ' Data for digit 1 and send to max7219
Dig_val2 = Dis And &B11110000 : Shift Dig_val2 , Right , 4: W = Makeint(dig_val2 , 2): Call Show(w) ' Data for Digit 2 and send to nax7219

Sub Show(var As Word) ' send data to max7219
Data_out = Var
Reset Cs
For N = 1 To 16
Reset Clk
Y = Data_out And &H8000
Shift Data_out , Left , 1
If Y = &H8000 Then
Set Dout
Else
Reset Dout
End If
Set Clk
Next
Set Cs
End Sub

Good luck
Twenty

Duval JP · Joined: 22 Jun 2004 Posts: 1161 Location: France

sorry,
my program doesnt use 1 wire communication but the old but cheap 4511 drivers

JP

Xeus · Joined: 28 Jan 2005 Posts: 4

Thank you
i'm will try it

Xeus · Joined: 28 Jan 2005 Posts: 4

Sorry for the mistakes!!!