Low speed AVR oscilloscope V2.00 (Is updated on 19 Mar 2011)

>> The firmware was updated on 19 Mar 2011 <<

A few months ago a friend of mine -car mechanical at profession- told me that he had problem with some car sensors. He couldn't check, with a simple multimeter, if a sensor was working properly. I advised him to buy a LCD oscilloscope instead of a normal oscilloscope, because of its small size. The use of an oscilloscope is very helpful because you can see the waveform that is produced by a "healthy" in-circuit-sensor* and you can compare it with the waveform of a "suspect" in-circuit-sensor.
After that, he told me that this oscilloscope costs a "fortune" for him as he has a small car service shop. I offered to help him by designing and constructing a small, cheap and workable LCD oscilloscope for him.

*in-circuit-sensor is the sensor which is connected on a board (PCB) or it's connected somewhere in the car. It's not a disconnected sensor.

You can download the source code, hex, schematic diagram,PCB and picture of the circuit .

Step 1 Selecting the components

As the circuit has to be constituted by a few and cheap components, I chose the DEM128064A graphical LCD based on KS0108 controller chip to display the measured signals. The ATmega32 microcontroller is chosen because it has a lot of IN/OUT pins and a 2kB RAM size. 1kB is needed from gLCD and some bytes of the rest 1kB are used in C source code as registers. Because my oscilloscope has to read both AC and DC currents and at the same time it should have a High input resistance, I chose to use an LM358 which is a dual operational amplifier. The rest components like LM7805 , capacitors and resistors are very common and I won't refer to them.

Comments

[nehanikita]

this display is not available at my place...so any other option for this?

[WakeUpWolfgang]

Look at adafruit.com that is where I bought mine you can get it with a blue background with white text or black background and white text

[WakeUpWolfgang]

I know most of the parts are common but it is hard to read what they are from the schamatic may I have the parts list? I have the micro controller, screen and the amplifer but I am having a hard time reading the values of the other compoients.

[WakeUpWolfgang]

My total price is just under $42 I have some parts still in the mail but I will post a photo of it once I have it together and working

[WakeUpWolfgang]

I have a list of most of the parts but I don't know what the vale of D1. I did a searchfor 8V2(that is what it says on the schematic) and could not find it on jameco.

[serasidis]

The diode D1 is a zener diode at 8.2 Volts.

[WakeUpWolfgang]

Thanks I have found the parts at jameco.com but the screen I found the screen at adafruit.com and my total price is around $45 -50 USD if you buy all new parts and 30 of it is the screen

[WakeUpWolfgang]

(removed by author or community request)

[CBX]

have you considered using an external ADC?

Will it work at 8mhz?

[serasidis]

>>have you considered using an external ADC?
That would be a good idea but there is not free time for that!

>>Will it work at 8mhz?
Yes, but you must change the crystal frequency in the source code and re-compile it. The circuit will run in low performance.

[hATEmATH]

great! i'd like to make one also.

[mtnkh]

hi
thanks for your perfect site.
I need some explanation for the structure of the c file of this project.could you help me please?
if you mail me that i will be pleased.
this is my email address:[e-mail]

[serasidis]

The firmware has been updated to version 2.00

- Now, indications such as voltage and frequency are displayed on LCD.
- A small increment of sampling rate has been made too.

[rolocz]

Hello, nice project. Some time ago I (re) built and XY oscilloscope that uses external ADCs. That makes it a lot faster and a lot of nice curves can be displayed. Not as well finished or as useful as yours, but still fun to build and try. If you please you can check it in my website: http://eercz.com/en/avr_xy_oscilloscope_nokia_lcd

Regards

[qz9090]

Would you recommend a inexpensive 1:10 probe that I can used with this scope? Maybe a supplier and part number? Thanks.

[com4both]

 very good project..i have seen pc based oscilloscope...
but this one is very good.....

where can i get the lcd....its not available here at my place...
i can make online shopping..
can anybody  who made this project, send me few links for online shopping

what will be the cost of the LCD?

what is ks0108...do i need to buy this controller or simply lcd?

make my doubt clear....

[dan_dan]

how much did the lcd display cost, nice design tho.

[matchett808]

hey....what was your total cost? Very nice job though...am needing a oscilloscope so wondering if this is the cheapest way to skin this particular cat.lol

[geeklord]

The Pololu AVR programmer has a built in SLO-scope that I really like. It only works from 0-5v, and only on windows, however. But its only $20(USD), so its great for simple low voltage applications.

[serasidis]

The all project (including the probe) cost me about 70 euro.

[mog123]

I did the whole project in ~20-30 euro (<100 PLN)

[matchett808]

nice one....good build and quite cheep.....compared to the commercial ones i have sourced.

[jamilm9]

if you don't want to make this get this $50 prebuilt o-scope.
http://www.seeedstudio.com/depot/digital-storage-oscilloscope-with-panels-p-167.html
there is also a kit but it needs smd soldering.

[senfield]

hello serasidis, we can use the mega32l instead mega32, the code is the same? , about the xtal, change the frequency or something? (cause the max clock of the mega32 (16mhz) , i have a mega32l-8pi (8mhz) max, thanks

[withume]

hlp, me to display the voltage,and frequency in the display........what changes hv 2 be done with this.

[pkumarhu]

hi my name is pramod i hve done tis project it is very nice but i like to do some modifications i like to display the voltage and frequency on the lcd screen so pls help me in changing the code

[adie_hendri]

hi to ALL heloo Mr serasidis mr serasidis giveme advise u havent my question

[mog123]

Hey, I finished my oscilloscope!

http://i39.tinypic.com/30vk45l.jpg

It turns out i didn't need to use an inverter, your screen is the same as mine!
Although I have a problem: I'm using software 1.01 and I can't use the time/div buttons (left and right). Do you know a solution?

[withume]

can this project be done using atmega32L, instead of 32 since atmega32 is not available for us.........pls reply me as soon as possible

[serasidis]

Yes, you can use ATmega32L instead of ATmega32.

[mog123]

Hey, I found an LCD that input matches yours (and its a KS108). But 3 bits are negated (CS1 CS2 RST). Could you look in the datasheet if it will work like yours or will I have to change something in the sourcecode?
Heres the datasheet
http://www.artronic.pl/o_produkcie.php?id=612

[serasidis]

I think the LCD you mentioned needs inverted CS1, CS2 and RST signals. You have 2 choices: either you edit the lcd.c file correcting the commands for these pins or you put 3 NOT gates between lcd pins and AVR pins. Depend on you what you will do. I would suggest you to find a pin-compatible LCD to build this project.

[mog123]

so will this code be ok? I can't seem to find a screen with a compatible pinout ;/

http://mog123123.googlepages.com/glcd2.c

Besides I see that the "signal wire" of the probe connector (K1) is soldered to both ground(0V) and Capacitor (C2) why is that?

[mog123]

OK I'm gonna use a 74hct04 with the screen I showed you to invert CS1 CS2 and RSTB. I have one question though: Can I use an ATMEGA16 instead of 32? The hex file is only 10kB so it should fit or am I missing something important? Please reply.

[adie_hendri]

hello im ADIE im so excited, so proud this great why in serasidis web , i can't join in forum . server not fungtion i will build up avr oscilosope u can help, an give me advise?? oh yeah why this project is the limit 5khz, can you explain?? thanks best regars

[thatonekid]

please post the schematic as a file so that it can be downloaded. thank you

[serasidis]

You can download all you need from my web site:
http://www.serasidis.gr/circuits/AVR_oscilloscope/avr_oscilloscope.htm

[DELETED_toolazy2p]

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[serasidis]

The main problem (up to now) is that the microcontroller spends a lot of time to draw the graphical LCD. When I improve this part of the code, the oscilloscope will measure up to 7.5kHz that is the half of 15kSPS (kilo Samples Per Second). 15kSPS is the maximum hardware limit that the ATmega32 ADC (Analog to Digital Converter) can measure.

[biojae]

So if i used a 1.2 ghz adc i could get that much more precission?