LED Machine Tach For Tired Eyes

[DanPBP]

First, I would like to say thanks to Sam for sending me the code and the schematic.

Second, I have a question: what is the maximum RPM this circuit/code can read?

Thanks!

Daniel.

[Archangel]

First, I would like to say thanks to Sam for sending me the code and the schematic.

Second, I have a question: what is the maximum RPM this circuit/code can read?

Thanks!

Daniel.

Hi Daniel,
I added this line:

if displays > 9999 then displays = 9999

to keep the display from rolling over 9999. What use do you have for this tach? I do not think I would try it on a turbine, as it updates too slowly, but it was written for a lathe. It will go over 9999 without that line, the max is unexplored. Perhaps someone who is skilled at math could tell you. The displays can be cascaded, if you feel adventurous.

[DanPBP]

What use do you have for this tach?

I have a few brushless R/C trucks, they have an optic sensor on the transmission and I would like to read the RPM. They go up to 50.000 RPM! I'll give it a try.

[Archangel]

I have a few brushless R/C trucks, they have an optic sensor on the transmission and I would like to read the RPM. They go up to 50.000 RPM! I'll give it a try.

Cool, keep us posted, I am curious as to the limits of count. I am thinking the variable might overflow if RPM goes too high, and you might have to alter the sampling rate or use some form of prescaler.

[fratello]

I try to use code from post #1 to my thermometer with 16F628A, DS18B20 and LED display ( like in : http://melabs.com/resources/articles/ledart.htm fig.6). To another topic, I receive one working code, from one user (thanks !).
But, I am still disappointed, because MY code don't work. Please, what's wrong with him ? Thank you !

@ DEVICE pic16F628A, intOSC_osc_noclkout, WDT_OFF, PWRT_ON, MCLR_OFF, LVP_OFF, CPD_OFF, PROTECT_OFF    
TRISA= %11110000                   ' RA0..3=Outputs RA4=Input
TRISB= %00000000 			             ' RB0..RB7=Outputs
CMCON=7                            ' Disable comparators


    
    DQ          VAR PORTA.4
    DS18B20_12bit 	CON %01111111           ' 750ms,   0.0625°C       
    I           VAR BYTE
    SIGN        VAR BIT
    TEMPERATURE     VAR WORD ; TEMPERATURE REGISTER
    n			var byte
segments 		var portb
digits		    var porta
value			var word



   
MAINloop :   
        OWOUT DQ ,1,[$CC,$44]
      
WaitLoop: 
While not DQ
Wend
        
        OWOUT DQ ,1,[$CC,$BE]
        OWIN  DQ ,2,[TEMPERATURE.LOWBYTE , TEMPERATURE.HIGHBYTE]
        
        IF TEMPERATURE.15 = 1 THEN
            TEMPERATURE = (65535 - TEMPERATURE) + 1
            SIGN = 1
        ELSE
            SIGN = 0
        ENDIF
        
        value = (TEMPERATURE * 10)/16


        gosub display
        
goto mainloop


' Subroutine to send the number (0 - 9999) in Value to LEDs
display:
	For i = 0 To 3		' Loop through 4 digits
		n = value Dig i	  ' Get digit to display
		GoSub display1	' Display the digit
				      ' Leave it on 2 millisecondS
	Next i			      ' Do next digit
	
	Return


' Surboutine to display one digit on LED
'  i = digit number
'  n = number to display
display1:
	'Digits = $ff		' All digits off to prevent ghosting

	' Convert binary number in n to segments for LED
	Lookup n, [$40, $79, $24, $30, $19, $12, $02, $78, $00, $18,$7f], Segments
  ' logic low complements
	' Set digit pin i to 0 (on) and the rest of the pins to 1 (off)
	Digits = ~Dcd i
  Pause 1 'Increase to make digits brighter and flicker worse
	Return
	
	end

[Acetronics2]

Hi, Fratello

One thing is obvious ...

The " Waitloop " , for sure, can't be used whith multiplexed LED's ...


One thing is surprising ...

Do you think your temp calculation is compatible with the provided Led Display ???


One thing is really hazardous ...

While dealing with the display ... you write over your PortA inputs as well as outputs !

Alain

[fratello]

One, two, three things are for sure : I am a sucker !
It's not the first time when "the language barrier" make me problem...I'm really sorry if I borried somebody .
In the link that I posted it's the schematic (with reference to PBP code) I tried to make...It's sure that I must careful read (and understand !). Thank You verry much for attention and reply ! All the best !