Help needed desperately with PIC LCF meter

[ericgibbs]

i hav made the pic lcf meter using 16f628A, but when i turned on the meter,only one line of rectangular boxes is appearing on lcd (i.e noting changed) & nothing happening.. i have checked all the connection which are alright..
i have a doubt abt my 3.2768 crystal, which was not available and i found it by chance. the value on the crystal is written as : ECS v 3.27 - 17 ,,, ..what do u think ???

hi,
I cannot identify the crystal from that number.

A common problem with LCD's....
is the R/W pin connected to 0V.?
do you have a contrast pot on the LCD.?

 

[tariq7868]

to program the ic pic 16f628A for Lcf meter , can anybody plz tell what config bit to set ? i am using mepwin 500 universal programmer and it gives me some options to set the config word (see in the attached image)

so which of the check boxes i should tick ???

 

[ericgibbs]

to program the ic pic 16f628A for Lcf meter , can anybody plz tell what config bit to set ? i am using mepwin 500 universal programmer and it gives me some options to set the config word (see in the attached image)

so which of the check boxes i should tick ???

hi,
All this information is on the Header of the asm file.!

Look at these two images.

A '1' means its checked a '0' is not..OK

 

[tariq7868]

gosh! Thanks alot for replying that fast...i am also having the same trouble just as al was having ...ie no just a single line of boxes on the lcd...so eric can you plz also upload the asm file for lcd testing as well as led toggler (RA3 pin toggler) u uploaded( the previous upload seems to be damaged ?? thnx

note tht i have grounded R/W and have a contrast pot..


thnx a lot

 

[ericgibbs]

gosh! Thanks alot for replying that fast...i am also having the same trouble just as al was having ...ie no just a single line of boxes on the lcd...so eric can you plz also upload the asm file for lcd testing as well as led toggler (RA3 pin toggler) u uploaded( the previous upload seems to be damaged ?? thnx

note tht i have grounded R/W and have a contrast pot..


thnx a lot

hi,
Here is the LCD test asm... 'AlsLCD1.asm'

Where in this thread is the 'Led Toggler' program you refer to.??

 

[tariq7868]

Al,

Have you run Erick's code that changes the value of a single pin. I seen where you said it seemed to run away. Did it toggle the pin?

Maybe build some other tools first?

A programmer with ICD would a good tool for debugging. You could set breakpoints inside the LCD code and check the state of each line with a volt meter or a logic probe.

For 16F work a serial ICD2 is fast enough. Bill is closing out the the Inchworms ICD2's so the price is right. They are mostly a 16F877A, a few transistors, and a handful of resistors and caps. Uses code from Microchip's ICD2 so it will work with MPLAB as long as Microchip supports the ICD2.

A PICkit2 or Bills clone the Junebug is even better. It runs at USB speed and does double duty as a 3 channel logic analyzer. That would be nice for looking at the LCD control lines on the current project. 3 lines is not much but you would be suprised what you can do with it.

Peter Anderson has a PIC programed as a logic prob for under $3.


Or you can build an Mondo SuperProge which has 17 or 18 functions including LC. These use a 4 char 7 seg LED display.

RA3 is the unused pin in the lcf meter, so i thought i should also test it by toggling led slowly just to confirm whether my pic is starting/working or not...just as u and others suggested..actually i m really new to microcontroller and so far have done programming for 8051 (in C) so thats why i hav to bother u with such minor things...

thnx for the help...

 

[ericgibbs]

RA3 is the unused pin in the lcf meter, so i thought i should also test it by toggling led slowly just to confirm whether my pic is starting/working or not...just as u and others suggested..actually i m really new to microcontroller and so far have done programming for 8051 (in C) so thats why i hav to bother u with such minor things...

thnx for the help...

hi,
I will look at the program for the toggle.

 

[ericgibbs]

hi,
A short asm program.

All that it does is set all PORTB pins high for 0.5sec and then low for 0.5s,,, repeating forever.

No LCD programming.

 

[lynx]

Hi

i had that LCF meter working fine for long time..
recently i decided to remove the rotery switch and keep the instrument
as L meter everything went fine and it was measuring ok but after i tried
to put it in a plastic box, it fails to measure correctly.. especially very
small inductors!

a once measured 3.3uH inductor now the instrument show it is 17mH
and the measurement hardly stays steady..

looking at the board and components..couldn't find something wrong...
any ideas what might has happend?!

 

[ericgibbs]

Hi

i had that LCF meter working fine for long time..
recently i decided to remove the rotery switch and keep the instrument
as L meter everything went fine and it was measuring ok but after i tried
to put it in a plastic box, it fails to measure correctly.. especially very
small inductors!

a once measured 3.3uH inductor now the instrument show it is 17mH
and the measurement hardly stays steady..

looking at the board and components..couldn't find something wrong...
any ideas what might has happend?!

hi,
Referring to the circuit in the pdf.

When you removed the rotary switch, did you change or remove IC3b/c or d.??

If you removed IC3b/c, what did you connect to IC3d pin8.?

 

[bigal_scorpio]

Hi Eric and Lynx,

Just wondering if since maybe its a while since using the LC meter if you remembered to short the leads before measuring inductors to null the reading?

Also I have noticed that even though the LCD may look OK, when the battery is failing the readings can vary dramatically.

Hope this helps.......Al

 

[lynx]

Ηι!

thanks both of you for your replies!

hi,
Referring to the circuit in the pdf.

When you removed the rotary switch, did you change or remove IC3b/c or d.??

If you removed IC3b/c, what did you connect to IC3d pin8.?

no i haven't removed anything else other than the rotary switch..
the cables are connected so the instrument can work as L meter

Hi Eric and Lynx,

Just wondering if since maybe its a while since using the LC meter if you remembered to short the leads before measuring inductors to null the reading?

Also I have noticed that even though the LCD may look OK, when the battery is failing the readings can vary dramatically.

Hope this helps.......Al

yes i'm shorting the leads so i can null the instrument with the push button...

no..the battery is new...


when the cables are shorted and the instrument is nulled or when i probe an inductor...
the frequency and the inductance doesn't stay steady instead it starts to raise
for example:

17584Hz
37.694uH

17596Hz
43.576uH

17609Hz
51.799uH

and so on... and also the measurement is not the correct one

 

[kasamiko]

I'm planning to built this project too but reluctant due to the fact of the hard to find XTAL..does the 3.2768MHz crystal matters for the accuracy of this meter? Can I used a much standard values like 4,8,10,12 or 20Mhz instead of 3.2768MHz by changing the xtal value in the source code?

 

[ericgibbs]

I'm planning to built this project too but reluctant due to the fact of the hard to find XTAL..does the 3.2768MHz crystal matters for the accuracy of this meter? Can I used a much standard values like 4,8,10,12 or 20Mhz instead of 3.2768MHz by changing the xtal value in the source code?

hi,
The 3.2768MHz crystal is essential, any other frequency will not give the correct readings.
The program is written only for a 3.27MHz crystal.

 

[bigal_scorpio]

I'm planning to built this project too but reluctant due to the fact of the hard to find XTAL..does the 3.2768MHz crystal matters for the accuracy of this meter? Can I used a much standard values like 4,8,10,12 or 20Mhz instead of 3.2768MHz by changing the xtal value in the source code?

Hi mate,

As Eric says, the frequency is very important. However there may be a quick and easy solution to your problem.

If you can get a cheap or even broken battery clock (the type that has just one battery and fingers) you should find the exact crystal in it to use.

I have seen a lot of these and they are usually available for about a pound here in the UK, so they should be available where you are I think?

Hope this helps.......Al

BTW the Crystal in them tends to be cylindrical but this is of no matter. But be careful removing them they are quite delicate.

 

[lynx]

i think you forgot about me any opinions concerning my problem?

 

[kasamiko]

hi,
The 3.2768MHz crystal is essential, any other frequency will not give the correct readings.
The program is written only for a 3.27MHz crystal.

how about modifying the code and change the clock to 4mhz? is that possible? or as simple as that?

oh..never mind...here's the good news below...

Hi mate,

As Eric says, the frequency is very important. However there may be a quick and easy solution to your problem.

If you can get a cheap or even broken battery clock (the type that has just one battery and fingers) you should find the exact crystal in it to use.

I have seen a lot of these and they are usually available for about a pound here in the UK, so they should be available where you are I think?

Hope this helps.......Al

BTW the Crystal in them tends to be cylindrical but this is of no matter. But be careful removing them they are quite delicate.

You mean the cheap quartz clock? like this?

**broken link removed**

yes i got a lot of this lying around with exhausted battery.... are all of them uses same crystal frequency??

i was thinking it was 32,768 Hertz or 32.768 Khz???

TIA

 

[bigal_scorpio]

i was thinking it was 32,768 Hertz or 32.768 Khz???

TIA

Ooops, you are correct Kasamiko, I must be having one of those days.

Until I actually looked again at the drawing I was convinced that the freq was 32.768khz. Doh! Plans scuppered, but I will see if I have a 3.768mhz crystal in my bits box and if I have I will send it to the guy free. It was my bad that got his hopes up after all.

Al

 

[kasamiko]

hi,
The 3.2768MHz crystal is essential, any other frequency will not give the correct readings.
The program is written only for a 3.27MHz crystal.

Ooops, you are correct Kasamiko, I must be having one of those days.

Until I actually looked again at the drawing I was convinced that the freq was 32.768khz. Doh! Plans scuppered, but I will see if I have a 3.768mhz crystal in my bits box and if I have I will send it to the guy free. It was my bad that got his hopes up after all.

Al

I'll try my luck on some local distributors....

Wished me luck...

 

[lynx]

you guys keep ignoring my posts..why? there's nothing could
advice me for the problem?

this instrument is rather simple other than the PIC there are
a couple of resistors and capacitors, i can't see what can cause
such mulfunction..