How to display more than 65536 with MAX7219

[isaac]

its installed ok
the upgrade was from crowhill
here is the readme file

Isaac

[mackrackit]

Are you using an old version of MCS?
Do not know if that would make a difference or not. When I upgraded PBP I also upgraded MCS and MPLAB.

[skimask]

I thought MCS 3.0.0.5 was the first version to recognize PBPL?

[RussMartin]

An upgrade to PBP 2.50B will give you LONG variables. From there, you can split up your 'huge' number into smaller numbers and display the chunks individually.

Is there another way i can use to display the number without having to use
Long?

isaac, depending on what you need, you may also be able to manipulate your data in software and massage it into individual digits for serial output. What is the nature of the information you want to read? And from what is that information derived?

[isaac]

Hi Russ

i am trying to implement a 6 digit display
the problem is my variable Max_Disp which holds the data that is displayed
can only hold up to 5 digits so 12345 displays ok but when its 123456
this is grater than a word variable can hold so i need so help in how to do this i am following all the advice given but still lost

Regards
ISAAC

isaac, depending on what you need, you may also be able to manipulate your data in software and massage it into individual digits for serial output. What is the nature of the information you want to read? And from what is that information derived?

	
Again:		
	Max_Disp=12345
	Gosub Display			' Display the Value of Counter
	Pause 150			' Delay, so we can see whats happening
  goto again


Display:
	Digit=0						' Start at Digit 0 of Max_Disp Variable
	For Position=6 to 1 step -1			' Start at Farthest Right of Display 		
	Register=Position				' Place Position into Register
	R_Val=Max_Disp Dig Digit			' Extract the individual numbers from Max_Disp			
	If Max_Disp<10 and Position=3 then R_Val=15	' Zero Suppression for the second digit
	If Max_Disp<100 and Position=2 then R_Val=15	' Zero Suppression for the Third digit
	If Max_Disp<1000 and Position=1 then R_Val=15	' Zero Suppression for the Forth digit
	If Max_Disp<10000 and Position=0 then R_Val=15	' Zero Suppression for the Fifth digit
	If Digit=Max_Dp then R_Val.7=1			' Place the decimal point, held in Max_DP
	Gosub Transfer					' Transfer the 16-bit Word to the MAX7219
	If Digit>=5 then Digit=0			' We only need the first 6 digits
	Digit=Digit+1					' Point to next Digit within Max_Disp
	Next Position					' Close the Loop
	Return						' Exit from subroutine

' Send a 16-bit word to the MAX7219 
Transfer:
  	Shiftout Dta,Clk,msbfirst,[Register,R_Val] ' Shift Out the Register first, then the data
	High Load				' The data is now acted upon
@	Nop
@	Nop					' A small delay to ensure correct clocking times
	Low Load				' Disable the MAX7219 
	Return					' Exit from Subroutine

[skimask]

can only hold up to 5 digits so 12345 displays ok but when its 123456
this is grater than a word variable can hold so i need so help in how to do this i am following all the advice given but still lost
Regards
ISAAC

As I said in the other post on the basically the same subject, think fingers and hands. A WORD (hand) can only 'hold' 5 digits (fingers), you can count up to 10,000 but you can't count up to 100,000...
So, two words (hands) to hold your data, one word (hand) holds 0-9999 the other word (hand) holds the places above 9999.

max_displow = 0 : max_disphigh = 0
Again: max_displow=maxdisplow+1
if max_displow>999 then maxdisplow=maxdisplow-1000 : maxdisphigh=maxdisphigh+1
Gosub Display : Pause 150 : goto again
Display: For Position=1 to 6 step -1 : Register=Position
R_Val=Max_Disphigh Dig Digit : if position>3 then r_val=max_displow dig digit
Gosub Transfer : Digit=Digit+1 : Next Position : Return
Transfer: Shiftout Dta,Clk,msbfirst,[Register,R_Val] : load=1 : load=1
load=0 : return

But again, get PBPL and LONGs working and it'll be a bit easier...

[RussMartin]

I've looked at the MAX7219 data sheet:

http://datasheets.maxim-ic.com/en/ds...19-MAX7221.pdf

. . . but only briefly.

It looks to me (on page 6) as if you send each digit separately, along with the address of the digit's position (Table 2 on page 7). It also appears that the MAX7219 would be happy with a 4-bit BCD input for each digit. This means you can break your large number down into individual digits, each of which is only 4 bits and can be accomodated by a byte variable. Then you send each digit, and its position address, in a 16-bit word to the display.

But there's no way to tell you how to break down the number without knowing where you are getting the number from in the first place. Are you counting something? Or measuring something? What is your input? Why do you need 6 digits of output? What is the display telling--this many somethings or this much something?