Please help me understand this code

[Bruce]

In my DEBUG line "I" shows up as 0,2,4,5 randomly

You probably have several timer interrupts while it's inside your DO LOOP, so I ends up with unexpected values.

Example: With i = i + 1 being first in your timer interupt, it's changing the value of i on every interrupt, and sometimes even during the process of PBP trying to output everything with DEBUG.

When DEBUG actually starts, your interrupt is still changing I before PBP outputs it.

[Jerson]

Try this. Changes are in Bold

'---[INT - interrupt handler]------Signal found at RB0, take a reading
SignalFound:
    T1CON.0 = 0                             ; Stop timer1
    i = i + 1                               
    FValue = TMR1H * 256 + TMR1L + fvalue   ; Add 10 readings to FValue
    if i >= 10 then                        ' COMPARISON CHANGED TO >=
        fvalue = fvalue / i                ; get the average of one reading CHANGED HERE
        i = 0                               ; Reset counter
        ReadFlag = 1                        ; FValue is ready to read 
    endif        
    TMR1H = 21                              ; reset timer1 to 60mS
    TMR1L = 167
    T1CON.0 = 1                             ; Start timer1
@ INT_RETURN

[lilimike]

Hi Bruce and Jersen,

That is really fast !

Jerson,
I was able to observe the proper values by moving the DEBUG line inside the INT handler.

Is there a more efficient way to observe variables values within a program?
It seams like LCDOUT and DEBUG are taking too long to operate and are giving false values.

Thank you

Mike

[lilimike]

Bruce,

I came across this link you wrote Entitled "Using MicroCode Studio ICD
With The PIC16F628 Microcontroller" http://www.rentron.com/PicBasic/MCS_X3.htm
Would this enable me to view each step of a program as well as where the PIC timer is at while executing a specific line of code?

Mike

[Bruce]

Hi Mike,

Yep. MCS+ ICD is very handy if you have the paid version of MCS+. But if you're trying to view real-time timer values, I would go with MPLAB/MPSIM.

By the time you LCDOUT, SEROUT, whatever, the timer is long past the value you're displaying.

What precisely is it you need to do?

[lilimike]

I didn't think I could see real time values with MPSIM using a program written with PBP!
I will give it a try, I guess I have to invest a little time learning the Stimulus properly, I have done very little assembly and was able to test buttons triggering LEDs but when I started going deeper into this I kind of got distracted with PBP.

I am building an ultrasonic distance measurement device, I have seen some circuits here and there but I really want to fully understand what I am doing and build my own. I don't have any code to show just yet because I have started to isolate the different parts of my code and it doesn't look like any program right now.
What I am trying to achieve is using Daryl's Interrupts.
Using TMR1_INT I send HPWM and using INT_INT I detect the echo from the Rx on RB0.

I keep trying to tell myself that the PIC is running fast but I am always amazed with how much I underestimate the speed at witch it operates.

I think I am not too far from something, just wish I could slow down everything and observe what is going on during each operation of code (other than the operation itself)
I guess MPSIM is probably the way to go?

Mike

[lilimike]

I got PBP running with MPSIM and now I finely see what is happening and when, thanks for this info.

Mike