CCP / 24 bit timer / 1hz to 150 hz range

[ELCouz]

Make you code to ignore the value next to your WDT call.

Something like that:

call wdt
then put a flag like wdtcalled = 1

and before displaying the value look for the flag (if 1 then skip or display the last value)and after that reset it.

It's a dirty trick but it will work ;)



Regards,
Laurent

[Macas]

Thanks for your reply ELCouz by i already tried that and didnt work.

Here's my code:

[ELCouz]

There's a problem with your code...

You want to use the watch dog timer BUT you don't use restart_wdt() function which tell reset the WDT. If you don't put this in your code loop every 1024ms your code the pic will reboot. That's why you got an erroneous value.

Please search the forum for proper use of the WDT and read the CCS C compiler help.

Regards,
Laurent

[Macas]

Hi,
but i really do want to reboot because my code is stucking somewhere.

[Salenko]

Hi everyone,

Compiler version : PCW 4.057

I wrote this code after reading whole messages of this thread, measures aren't accurate for low frequencies ( I got 11.4 and 10.04 instead of 10 Hz, 19.58 and 25.91 instead of 20 Hz) and when I move to higher frequencies I got absurd values into my screen ( example for 150 Hz , I got 0.79 Hz, 77Hz and 94340.11 Hz ) .

I'm using a precise pulse generator.

Do you think that I miss something in my code ?

Thank you for any suggestion guys.

[PCM programmer]

The problem is in your frequency calculation formula. If you're doing
floating point math, then you don't need the integer round-off stuff in
the formula. The formula just becomes this:

[Salenko]

Hi and thanks PCM,

I've changed the frequency formula , but I'm still getting the same wrong values.

[PCM programmer]

Somewhere else in the code you posted, you have changed something so that it doesn't work. Instead searching for the problem, I'm just going to post some working code. This code was tested with vs. 4.057 and vs. 4.105.

I set my function generator to give 10 Hz, and I got this output:

[Salenko]

Hi PCM,

finally I got a working code !

the error in my code was the use of:

[vsmguy]

[alextee89]

Here is the test program:
Code:

#include <16F628.h>
#fuses HS, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 20000000)
#use rs232 (baud=9600,parity=N,xmit=PIN_B2,rcv=PIN_B1,bits=8)

#priority CCP1, TIMER1

#define BytePtr(var, offset) (char *)((char*)&var + offset)

#byte PIR1 = 0x0C
#bit TMR1IF = PIR1.0

int8 gc_timer1_extension = 0;
int8 gc_capture_flag = FALSE;
int32 g32_ccp_delta;

//------------------------------------------------------
#int_timer1
void timer1_isr(void)
{
gc_timer1_extension++;
}

//------------------------------------------------------

#int_ccp1
void ccp1_isr(void)
{
char timer_ext_copy;
int32 current_ccp;
static int32 old_ccp = 0;

gc_capture_flag = TRUE;

current_ccp = (int32)CCP_1;

// Get local copy of the timer ext.
timer_ext_copy = gc_timer1_extension;


if(TMR1IF)
{
if(*BytePtr(current_ccp, 1) < 2) // Was CCP captured after Timer1 wrapped?
timer_ext_copy++; // If so, inc the copy of the timer ext.

// Since we know a timer interrupt is pending, let's just
// handle it here and now. That saves a little load off
// the processor.
gc_timer1_extension++; // Increment the real timer extension
TMR1IF = 0; // Then clear the Timer1 interrupt
}

// Insert the timer extension into the proper place in the 32-bit
// CCP value.
// ie., Insert it into location "EE" as follows: 0x00EEnnnn
// (nnnn = the CCP).
*BytePtr(current_ccp, 2) = timer_ext_copy;

g32_ccp_delta = (current_ccp > old_ccp) ? current_ccp - old_ccp : current_ccp + (0x1000000 - old_ccp);

// Save the current ccp value for next time.
old_ccp = current_ccp;

}

//=======================
void main()
{
float frequency;

int32 current_ccp_delta;

set_timer1(0);
setup_timer_1(T1_INTERNAL | T1_DIV_BY_1);

setup_ccp1(CCP_CAPTURE_RE);

// Enable interrupts.
clear_interrupt(INT_TIMER1);
enable_interrupts(INT_TIMER1);

clear_interrupt(INT_CCP1);
enable_interrupts(INT_CCP1);

enable_interrupts(GLOBAL);


while(1)
{
if(gc_capture_flag == TRUE)
{
disable_interrupts(GLOBAL);
current_ccp_delta = g32_ccp_delta;;
enable_interrupts(GLOBAL);

frequency = (5000000L / (float)current_ccp_delta);
printf("%4.2f\n\r", frequency);

gc_capture_flag = FALSE;
}
else
{
printf("No signal\n\r");
}

delay_ms(500);
}

}


if i am using 16f877a, izit just change to #include <16F877a.h> ?

[SergioGM17]

Hi!! First of all, sorry to bump this old thread.

Im using this code (ver 5.0xx), almost the same posted above, just using a LCD instead of a rs232, internal clock (4Mhz), to measure low freqs (0-3hz):

[PCM programmer]

To find the differences between your code and the forum's code:

1. Download ExamDiff from: https://www.prestosoft.com/edp_examdiff.asp
I have been using vs. 1.8 for years. I notice they are now up to vs. 1.9.

2. Make a new folder on your Windows desktop.
3. Copy the forum's code into a text editor and save it as "working.c"
in that folder.
4. Save your code into the same folder as problem.c or whatever you call it.
5. Run Examdiff and select those two files in the new folder to compare.
6. Examdiff will load both and show differences highlighted in yellow.
You can go to the View menu and have it show differences only, if you want.

Now start to undo the changes you made in your program, as you test
which one is causing the problem.

[temtronic]

Couple of comments, possible shortcuts to save time and pots of coffee..

Sounds like you always edit the same program, over and over again.
What I do with every PIC project is 1st, create a '1Hz LED' program, get it working then save it. I then copy the source, naming it 'pictype_program_v2.c', where pictype is the type of PIC, program is then name of the project. V2 means version 2.
I then edit the V2 version, compile, burn, test. I then copy v2 --> v3.
I then edit the V3 version,compile,burn, test. I then copy v2 --> v4.
Yes, it mkes for a LOT of files on the harddrive BUT I can go back to any previous version and not lose a day wondering which of the 3 or 4 or ?? changes I made didn't work. I have 1,000s of PIC files on this HD, but tons of room, have yet to 'clean up'.
I do something similar with 'fuses'. Since today's PIC have more fuses than instructions, I create a #INCLUDE file that has EVERY fuse in it, ONE per line, WITH a comment. Once I have the 1Hz LED program running, I save the 'fuses' file as 'pictype_1HZ_fuses.c'. This does 2 things. One, I have a set of known WORKING fuses for basic PIC operation. I copy/edit/save this for project specific requirements. Two, it 'cleans up' the main project. Just one #INCLUDE line not 20-30 lines of fuses information. 3rd, It saves me a LOT of typing AND retyping ! Say you decide to not use the WDT but you forget to type in 'no'WDT. You could spend hours not seeing why 'it worked before but not now'........

Jay

[SergioGM17]

Hi, thank you for your responses.

Started from zero, with a signal generator + pic + virtual terminal (rs232) and the code worked perfectly.

Now, using with my own input signal, works with the virtual terminal, but when I use the LCD (16x1, LM020L on proteus) on A or B ports, or mixed, it seems like the CCP stops functioning, showing the "no signal" msg.

Adding to that, the #include lcd.c is below the #define pins, and the lcd_init() is on main().

In the meantime I will test with another lcd module.

EDIT: Apparently was a problem with the printf's and something on proteus, seems like it is solved.

TY!