Seven Segment 3 digit display with large 8.5 in. digits using Picaxe 20X2 and MAX7219

A

Andres Rodriguez

New Member
The digit segments are made with LED strips. The Circuit is powered with a modified power supply from an old PC. The controls (switches, button and status lights are on a board that is attached to the power supply. The numbers displayed can be increased or decreased from that control panel or using an infrared remote controller. The code, schematic and PCB artwork is included in the post that follows this one. By the way, FnF are the initials of the club that will be using the sign, it stands for FETCH and FLY
finished-project.jpg fully-assembled-and-tested.jpg
 
Last edited:
A

Andres Rodriguez

New Member
Here is the code, schematic and PCB artwork. I use Express PCB software and will be glad to share the files for the schematic and PCB.
Code: 
'++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

'This program will drive a 3 digit seven segment display
'The hardware consists of a Picaxe 20X2 and a MAX7219 plus two Darlington arrays (UDN2982 and ULN2003)
'The SERTXD commands were used during debuging and are left in the code but commented out
'++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

  ' DIRECTIVES

#picaxe 20X2 ' specify the PICAXE processor
#no_data ' speed up the download
#no_table ' speed up the download
#terminal off ' disable terminal window

'   PIN ASSIGNEMENTS

Symbol load = C.2 ' briefly pulse C.2 to transfer data to LEDs
Symbol But = B.0
Symbol SW = B.2
Symbol Green = B.6
Symbol Red= B.4
Symbol SIGNL = C.0
Symbol Counter = W0
Symbol Valones = b2
Symbol Valtens = b3
Symbol Valhund = b4
b5=0
Counter=1

' Register addresses for the MAX7219
symbol decode = 9 ' decode register; specify digits to decode
symbol brite = 10 ' intensity (brightness) register; 15 = 100%
symbol scan = 11 ' scan-limit register; specify how many digits
symbol on_off = 12 ' 1 = display on; 0 = display off

' ============================= Begin Main Program =============================
setfreq m64
dirsb = %11111010 ' set portB as all outputs (except B.0 and B.2)
dirsc = %10111110 ' set portC as outputs (except C.6)
hspisetup spimode00,spifast ' set up hspi
' Initialize MAX7219
hspiout (scan,2) ' set scan limit for digits 0-2
pulsout load,1
hspiout (brite,15) ' set brightness to 5 (15 = 100%)
pulsout load,1
hspiout (decode,0) ' set BCD decoding for digits 0-3
pulsout load,1
hspiout (on_off,1) ' turn display on
pulsout load,1

'********TO SHOW THE INITIALS OF THE CLUB "FETCH n FLY"
hspiout (1,71) ' 1st LED from left = "F"
pulsout load,1
hspiout (2,21) ' 2nd LED from left = "n"
pulsout load,1
hspiout (3,71) ' 3rd LED from left = "F"
pulsout load,1
'***************************************

Pause 500
If PinC.0 = 1 then goto TV		'Check to see if numbers will be advanced usinf an IR controller
If PinB.2=0 then High B.6 else Low B.6 
endif
If PinB.2=1 then High B.4 else Low B.4 
endif
		Jump2:
button B.0,1,254,254,b5,1,pushed1
hspiout (brite,2) ' set brightness to 5 (15 = 100%)
pulsout load,1
pause 2500
hspiout (brite,15) ' set brightness to 5 (15 = 100%)
pulsout load,1
pause 2500
'sertxd ("Waiting for first push ")
Goto Jump2
		Pushed1:
Sertxd ("First button PUSH ")
b5=0
hspiout (decode,15) ' set BCD decoding for digits 0-3
pulsout load,1
		Calc:
'Sertxd ("CALCULATING ")
Valhund=counter/100
If Valhund=0 then Let Valhund=15
endif
Valtens=counter//100
Valtens=Valtens/10
if Counter>99 then goto Jump1 
If Valtens=0 then let Valtens=15
endif
		Jump1:
Valones=Counter//100
Valones=Valones//10

' Send data to the four digits
		Display:
Sertxd ("Start display ")
hspiout (1,Valhund) ' 1rst LED from left 
pulsout load,1
hspiout (2,Valtens) ' 2nd LED from left 
pulsout load,1
hspiout (3,Valones) ' 3rd LED from left 
pulsout load,1
Pause 500
	For b5=0 to 1
hspiout (brite,1) ' set brightness to 5 (15 = 100%)
pulsout load,1
Pause 1000
hspiout (brite,15) ' set brightness to 5 (15 = 100%)
pulsout load,1
Pause 2000
	next b5
b5=0
If PinC.0 = 1 then goto TV
		Sig:
If PinC.0 = 1 then goto TV		
button B.0,1,254,254,b5,1,pushed
If PinB.2=0 then High B.6 else Low B.6 
endif
If PinB.2=1 then High B.4 else Low B.4 
endif
Pause 5000
'sertxd ("Waiting for next push ")
Goto Sig
		Pushed:
'Sertxd ("Pushed again ")
If PinB.2=1 then Decr 
	INCR:
Counter=Counter+1
'sertxd (#Counter," Counter increased ")
b6=0
Goto Calc
		Decr:
Counter=Counter-1
'sertxd (#Counter," Counter Decreased ")
b6=0
Goto Calc

		TV:
'sertxd ("Waiting for TV Signal ")
high B.6
high B.4
'sertxd (" "#Counter," TV ")
If PinC.0 = 0 then goto sig		
irin [1000,TV],C.6,b6 ;wait for new signal
if b6 = 16 then INCR ;Increase
if b6 = 17 then DECR ;Decrease
if b6<>16 and b6<>17 then goto TV
Counter PCB.jpg
 

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Last edited:
W

westaust55

Moderator
If I might make some comments:
1. It is good practice to keep labels in the left most column of a program line. They are much easier to see/find that way.
As PICAXE manual 2 (page 5) states:
It is convention to only place labels on the left hand side of the screen.
All other commands should be indented by using the &#8216;tab key&#8217;.
This convention makes the program much easier to read and follow.
Click to expand...
2. Indenting the rest of the code with further indents for looping structures also makes it easier to see the structure.

3. While the program is not even getting close to filling a program slot, line for the tens and units such as:
Code: 
	Valtens=counter//100
	Valtens=Valtens/10
can be reduced to
Code: 
	Valtens=counter//100 / 10
4. In the Pushed1: subroutine, the line
Code: 
	if Counter>[COLOR="#FF0000"]9[/COLOR]9 then goto Jump1
should that be ??
Code: 
	if Counter> 9 then goto Jump1
otherwise you are blanking the tens digit when the number is in the range 10 to 99 when then tens digit should be displayed.
 
A

Andres Rodriguez

New Member
westaust55, Thank you for taking the time to review my project. Your input in this and other cases is spot on and greatly appreciated.

Marmitas
 
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