Uno circuit fault finding

Question

Hi, i'm new to Arduino, and I'm having a few issues with my first project. I decided to try and recreate the Digital Code Lock project posted on Digital Digest. I'm struggling with configuring the circuit itself. I've successfully uploaded the code to the Uno, but there's a few issues; -the buzzer sounds constantly. - the LCD display doesn't power up I've tried to lay the circuit out in a way that's straightforward to follow, but as I say, i'm pretty new to this. I found the circuit diagram hard to follow, as some of the connections shown differed slightly with my hardware (I tried to get as close to what the original poster listed as possible), especially the keypad. I suspect I've connected it up wrong, or put a component the wrong way round. I've dont some fault finding with my multi meter, and power seems to be getting to the components. I've attached some images. Can anyone tell me firstly if it looks like I've connected it up wrong? Message was edited by: Chris Swann - pictures added. 
 Attachments:

gadget.iom · Accepted Answer

Hi Fevvahz I'd go back over your wiring for the transistor/buzzer section of the circuit. The schematic shows the base of the transistor being connected to pin A1 of the Arduino through a resistor. I cannot see that connection on your photos, nor can I see a resistor. As rachaelp has already pointed out, the buzzer seems to be permanently wired to the 3.3V supply, completely bypassing the transistors. And as she also stated, you probably aren't getting a suitable connection from the glue on the LCD header. Also check the configuration of the wiring around the resistor for your LCD. It looks like you might have interpreted a join at the resistor/VEE junction which is actually not connected to VDD (No dot). Take a look at these suggestions and get back to us with your findings. Paul

rachaelp · Answer

Fevvahz wrote: -the buzzer sounds constantly. It looks from the pictures that you may have 3.3V permanently applied over the buzzer. If you follow the connection of the 3V3 and GND signals from the Arduino to your prototype board you will see that you then have a link from GND to one side of the buzzer and from 3V3 to the other side of the buzzer so it will always be on. Fevvahz wrote: - the LCD display doesn't power up I can only see the display side of the connections but it looks like you are just holding the wires in place with hot glue. I suspect you don't have good electrical connections here so it's not working. Either solder the wires into the board directly or solder in a 0.1" socket strip into it do you can plug into it like you do the Arduino or the prototype board. I've not gone through the connections in detail to see if they are in the right places. Best Regards, Rachael

Fevvahz · Answer

Well the beer flowed, and was welcome. Now, its time to conclude my tale....

Firstly, I had the jumpers from outputs 8,9,10 and 11 on the Arduino to the pins 12, 13, 14 and 15 respectively, instead of 11,12,13 and 14 that it should have been - that slight misalignment really messed up the functionality of the LCD screen. Once I'd checked again, and again, and again I finally found such a silly mistake.

Secondly, pin 16 on the LCD should have gone to the +'ve, but I'd put it in the middle of the positive 'side' of the breadboard, but not provided any power to it.

Thirdly, pin 3 on the LCD should have gone to the +'ve side of the 1k resistor.

I also had the keypad rotated the wrong way too.

It was really down to my poor reading of the diagram, but after a lot of reading, especially regarding the LCD pinouts, I finally got there. Here's a couple of pictures of the finished setup, all working;

gadget.iom · Answer

Hello Fevvahz I cannot see the images you attached. If you could post them on here I'll take a look at the circuit for you. Paul

Fevvahz · Answer

All sorted! It was a few things, and I'll detail them tomorrow, I'm going for a celebratory beer! Thanks every so much for all your help!

Uno circuit fault finding

Top Replies