How to display more than 65536 with MAX7219

[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?

[isaac]

I've looked at the MAX7219 data sheet:

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


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?

The 6 digits numbers are a set of values like 123456 of which 123 represents 12.3ft and 4.56 metres.
there would be 10 sets of number like that which would be stores in the
pics eeprom so those 10 sets of number would take up 40 bytes of the eeprom.
My thinking was that instead of using 2 Max7219 both connected for 3 digits each and display 12.3 on one and 4.56 on the 2nd .
i could save on hardware cost if i just display say the first 4 locations containing 123 & 456 with the Max7219 configured for 6 digits.
i can happily display them individaully but as i said its a waste on hardware.
i am sorry if i didn't explain myself better from the start.

Reagrds
Isaac

[isaac]

Hi Guys
i have just sorted out the problem i had with Microcode Studio and
PBPL and LONGs .
the problem was that there were CodeStudioPlus.exe and also CodeStudio.exe so i delated the later and i now have PBPL option.
who is going to be the first to show me how Long works with my problem

Regards
Isaac

[RussMartin]

The 6 digits numbers are a set of values like 123456 of which 123 represents 12.3ft and 4.56 metres.
there would be 10 sets of number like that which would be stores in the
pics eeprom so those 10 sets of number would take up 40 bytes of the eeprom.
My thinking was that instead of using 2 Max7219 both connected for 3 digits each and display 12.3 on one and 4.56 on the 2nd .

Then it looks to me like you don't need to use LONGs at all! In fact, I can't see how LONGs will help you.

In fact, it looks as if you are "multiplexing" two different numbers onto one display.

Since you are using only three digits per item, the largest of one of them (feet), even if multiplied by 10 for easy handling, is going to be 999, which is a lot less than 65,535, and the largest of the other (meters), even if multiplied by 100 for easy handling, is going to be 9999, which also is a lot less than 65,535. Each can be a WORD.

In fact, if you allow only three decimal positions for meters, it, too, can never be larger than 999.

Extract base 10 digits from each word as a binary-coded decimal (BCD) byte, then send each of them out along with a position address in a WORD for the display. Even the order you send them in doesn't matter much, since the word tells the display where that digit needs to appear.

What is the relationship between the two values being displayed? From where does the data come?