LC Metre

[AVRFreakMan1]

Anyone tried to build the "LC Metre" from site's New Links?

http://xavier.fenard.free.fr/LCMeter.htm

I breadboarded the logic circuit and tried with LCV100803.HEX(flash), LCEEV100803.HEX(EEPROM) files for the AT90S2313 u-C but the LCD works funny. It displays only the first 8 characters from the messages while they had up to 16 characters.
I know it should be an one line LCD and mine was 2x16 but this should not cause any problem. LCD internal character addressing is the same for the first line, nomatter how many more lines the LCD has. I tried 4 different LCDs, 2x16 and 2x20 but all displayed the same.
I'm pretty sure that my connections are ok(the schematic has a few errors but I corrected them). The problem must be on the firmware.

Anyway, I just want to check if it really works as an LC meter and its accuracy is ok. If yes I could spend some time to hack a bit the code and build a PCB for it.
The results so far have dissapointed me. :-\

Kyriakos

 

[MP1]

kyriakos, what changes were needed in the schematic?

Since you tested the circuit with several different display types, it would seem that the code is not correct for 4 bit display communication. Had you not tried other display types. my first guess would have been that you have one of those 16X1A displays.

MP

 

[AVRFreakMan1]

Well,
the circuit in general is unclear as for the values of many components(L,C) but it is easy to test the digital section without building the analog.
A majore error was in LCD data pins. They must be swaped. Where B0 must be B3(B0->B3,B1->B2,B2->B1,B3->B0). The rest data pins should be pushed gently down to ground.

About the LCD that displays only the first 8 chars, I just used a 16x1 LCD in a circuit that needed a 20x2 LCD. It displayed the first 8 chars from the 1st line and the first 8 chars from the 2nd line in the single line that the 16x1 LCD has.
So I assume that there is some confusion in initialization when you init the LCD for 1 or 2 lines.
I think that if I'll try a 16x1 LCD, it is going to display the data correctly.

Kyriakos

P.S.
>>MP
What do you mean by "16x1A displays"?
The letter "A" defines some special characteristics?

 

[MP1]

Some manufacturers made 16 X 1 displays which were 16 characters on one line, but the on-board electronics were actually 8 X 2. These were referred to as 16X1a.

MP

 

[AVRFreakMan1]

Thanx MP!

Useful info.
So the 16x1 LCD that I tried is actually from those 16x1A.
I'll test the whole circuit with this LCD in the weekend and see if it's worth the trouble so far.

Kyriakos

 

[AVRFreakMan1]

I gave up!
It doesn't work in any way. Even though I would bypass the LCD because it has a workable connection for a PC COM port, I cannot bypass the fact that it doesn't measure any coil or capacitor. The readings seem random. :-(

Kyriakos

 

[BOHDA]

Anyone tried to build the "LC Metre" from site's New Links?

http://xavier.fenard.free.fr/LCMeter.htm

I breadboarded the logic circuit and tried with LCV100803.HEX(flash), LCEEV100803.HEX(EEPROM) files for the AT90S2313 u-C but the LCD works funny. It displays only the first 8 characters from the messages while they had up to 16 characters.
I know it should be an one line LCD and mine was 2x16 but this should not cause any problem. LCD internal character addressing is the same for the first line, nomatter how many more lines the LCD has. I tried 4 different LCDs, 2x16 and 2x20 but all displayed the same.
I'm pretty sure that my connections are ok(the schematic has a few errors but I corrected them). The problem must be on the firmware.

Anyway, I just want to check if it really works as an LC meter and its accuracy is ok. If yes I could spend some time to hack a bit the code and build a PCB for it.
The results so far have dissapointed me. :-\

Kyriakos

LC_METER.txt

 

[BOHDA]

Sorry about my previous reply.I make an txt,instead of simple message.So I rewrite the previous with some adnotations.
I have buid the LC Meter.It works fine.I use the same hex that Kiriakos has mentioned.Also I use an 2x16 display because I did not have an 1x16[is HD44780 type].
All characters are displayed,even they are now separated on two lines.
The PCB is good,only in schematics are some minor mistakes.
I think the problem is,if the MCU was right written,in some bad conection between MCU and LCD display.You have to respect the PCB
.
Also you can contact Fenard,is open to consulting.
The values for oscillator are 400 pF and 49 uH.
I also do not use RS485 on PCB[ no conection between MCU and RS485].Fenard wrote to me and advise for this.
The working of LM311 oscillator is ease to detect by an oscilloscope,or an rf voltmeter[even on DC scale of DVM you can see at the output of LM the variyng voltage]

 

[AVRFreakMan1]

Hi BOHDA,
nice to hear that it works.

I followed the schematic in analog section. In my experience, it looked ok. It wasn't ok, that's why it doesn't show stable/correct values?
The PCB is unclear too and I was too lazy to try to extract the schematic from it!

In the breadbording circuit that I made, I tried LC values around those you mention(I found them in comments in the source code) but I had no luck. Maybe it was breadborad's fault. Loosy contacts and stuff..

I'm amazed by the fact that it shows you all the characters in LCD(even separated in two lines). I couldn't reproduce that. In my circuit it shows only the first 8 chars no matter what!

The advice regarding not using the RS485 was in order to keep the circuit free of RS485's spikes/noise or battery's life?
That was the only section it worked for me!
Actually I didn't use the RS485 converter, just took the Tx output from the AVR and used an RS232 converter to my PC but I could finally see what the LCD should show!

I don't know if I ever try(again) to make it work.
I'm actuallly looking now for a more sophisticated circuit that whould be able to measure inductance, capacitance and resistance in every component(LCR).
There was such a device(construction article) in ELEKTOR's magazine some years ago('97 ?) and it had a DSP to do the job.

Kyriakos