Math...

[DaOne]

Need some quick help with a math issue. I haven't had to do this in a long long time and for some reason I cant wrap my brain around this...

I have an input of 1 through 100 steps.

I need it to become 1000 through 2000 steps matching the inputs value.

Anyone wanna help my headache?

[wastrix]

Look at three things:
-What is the min. input?
-What is the input range?
-What is the output range?
-What is the offset?

I notice you specify 1-100, rather than 0-100. I will assume that was intended.

Min input: 1
Input range: 99
Output range: 1000
Offset: 1000

Formula is therefore:
out=(in-1)*(1000/99)+1000

Examples:
In=100, Out=2000
In=1, Out=1000
In=50.5, Out=1500 (Remember 50.5 is between 1 and 100, not 50)

[DaOne]

Thanks wastrix! yes it was intended to be 1-100. if it was a 0 -100 would this be the change?

out=in*(1000/100)+1000

Thanks again.

[wastrix]

That's correct.

[bill9399]

Originally Posted by wastrix

That's correct.

Or maybe not.

By my calculation

1-100 inclusive is a range of 100 (0 is your reference point)

Always confusing when you work with arrays and such which start with element x(0).

Try counting on your fingers. If you get stuck, use your toes as well.

[fanie]

Don't do the whole formula in one

out=in*(1000/100)+1000


Break it into it's individual steps, it's faster and you use less code.

[DaOne]

One more issue I keep banging my head with is interupts. I need to make one thats uses TMR1? to keep a contant 50 hertz pulse (servo) while allowing the main code to run. my main code is...

Device 16F88
Xtal 20

@CONFIG_REQ
@__CONFIG _CONFIG1, CP_OFF & CCP1_RB0 & DEBUG_OFF & WRT_PROTECT_OFF & CPD_OFF & LVP_OFF & BODEN_OFF & MCLR_OFF & PWRTE_ON & WDT_OFF & HS_OSC 
@__CONFIG _CONFIG2, IESO_ON & FCMEN_ON

All_Digital = TRUE
CMCON=7

TRISA = %00000001
TRISB = %00000000

Symbol Pin = PORTA.1		' Alias servo out pin
Symbol LED1 = PORTB.0
Symbol LED2 = PORTB.1
Symbol LED3 = PORTB.2
Symbol LED4 = PORTB.3
Symbol LED5 = PORTB.4
Symbol LED6 = PORTB.5
Symbol LED7 = PORTB.6
Symbol LED8 = PORTB.7
Symbol LED9 = PORTA.2
Symbol LED10 = PORTA.3
PORTA.1 = 0
PORTA.4 = 0
Dim p_one As Word
Dim p_two As Word
Dim duty As Dword
Dim out As Word
Dim Calc1 As Word
Dim Calc2 As Word

out = 1000
'main program loop here

main:
p_one = 0 ' reset counter values
p_two = 0

p_one = PulsIn PORTA.0, High
DelayMS 10
p_two = PulsIn PORTA.0, Low

duty = (p_one * 100) 
duty = duty / (p_one + p_two)


Calc1= (1000/99)+1000
Calc2= duty-1
out= Calc2 * Calc1


'****** This needs to be updates at 50 hertz by interupt****
Servo Pin , out
'***********************************************

If duty >= 1 Then LED1 = 1 : Else : LED1 = 0
If duty >= 10 Then LED2 = 1 : Else : LED2 = 0
If duty >= 20 Then LED3 = 1 : Else : LED3 = 0 
If duty >= 30 Then LED4 = 1 : Else : LED4 = 0 
If duty >= 40 Then LED5 = 1 : Else : LED5 = 0 
If duty >= 50 Then LED6 = 1 : Else : LED6 = 0 
If duty >= 60 Then LED7 = 1 : Else : LED7 = 0 
If duty >= 70 Then LED8 = 1 : Else : LED8 = 0 
If duty >= 80 Then LED9 = 1 : Else : LED9 = 0 
If duty >= 99 Then LED10 = 1 : Else : LED10 = 0 
      

GoTo main

End

I cant keep the servo output timed correctly without an interupt and I cant for the life of me figure out how to do it.

[wastrix]

@Fanie: If you'd be doing the whole thing in PDS anyway, that's debatable.

@Bill: Maybe, but in statistics range is defined as xMax - xMin, not inclusive.

@DaOne: You should probably start a new thread for this.

[fanie]

Easy if you use a PWM pic and a 4017 devide by 10.

If you run the PWM at 500Hz / 10 (4017) you have 50HZ. This is the easiest and most convenient way.
It will free the pic up to do other things while the PWM is maintained in the backround.

You can do it using interrupts if the 25c for the 4017 is too expensive

[DaOne]

Originally Posted by wastrix;92172.@DaOne:

You should probably start a new thread for this.

Will do... patiently waiting for your answer