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181  Using Arduino / General Electronics / Re: 4017 problem driving me nuts! on: June 10, 2012, 08:53:28 pm
It draws about 50 mA, so ~1mA to the transistors base should saturate it, but just in case I've tried it with as low as 470 ohms with the same results. The problem just seems to be that the 4017 resets itself for some reason.
182  Using Arduino / General Electronics / Re: 4017 problem driving me nuts! on: June 10, 2012, 08:34:42 pm
yep, relay works fine with this power supply.
183  Using Arduino / General Electronics / Re: 4017 problem driving me nuts! on: June 10, 2012, 06:44:02 pm
That was one of my initial thoughts as I'm only powering it from a 200 mA wall wart. however I disproved this by manually pulling transistors base high and seeing if the Q1 goes low when previously high, which it didn't.
184  Using Arduino / General Electronics / 4017 problem driving me nuts! on: June 10, 2012, 06:28:31 pm
So I've been trying to build a clap detector which switches a relay on and off when a clap is detected. I ended up with this schematic (modified from some website) . As far as I can tell, it amplifies whatever the microphone puts out, triggers the 555 which sends out a pulse to the clock pin of the 4017, making Q1 go high. When another clap is detected Q2 goes high, resetting the 4017 back to 0. If I disconnect Q1 from the resistor and check the state of Q1 with an led to ground then things work as expected, it turns on when I clap once and turns off when I clap again. However, if I attach Q1 back to the resistor - enabling the relay -, then whenever I clap Q1 goes high and within a few milliseconds it goes low again as if it had reset itself! I've messed around with the resistor value and adding a diode across the relay without success. Does anyone know what could be wrong?
185  Using Arduino / Displays / Re: Help identifying a scrapped LCD? on: March 16, 2012, 07:49:45 pm
Ok, I found the PCB's for both the wireless handset and the desk phone. Unfortunately, whatever company made this phone didn't feel it was necassary to label their PCB's with useful information such as company name and product name, so I can't even find a datasheet. I assume the handset had the same processor (before I ripped it of and threw it away, derp) as the desk phone but I can't find a datasheet for that either so I can't really follow the traces anywhere. Not sure how images could help at this stage but it wont hurt I guess:

http://imageshack.us/photo/my-images/20/p1090217.jpg/
http://imageshack.us/photo/my-images/850/p1090215w.jpg/
http://imageshack.us/photo/my-images/861/p1090214x.jpg/
http://imageshack.us/photo/my-images/831/p1090213v.jpg/
http://imageshack.us/photo/my-images/638/p1090212.jpg/
http://imageshack.us/photo/my-images/802/p1090211l.jpg/
http://imageshack.us/photo/my-images/191/p1090209v.jpg/
http://imageshack.us/photo/my-images/196/p1090207v.jpg/
186  Using Arduino / Displays / Re: Help identifying a scrapped LCD? on: March 16, 2012, 06:30:07 pm
Ok, I put 5 volts on the pink pin and got this:


I guess it came out of a phone...
Also this probably means that the pink pin is not the actually the contrast pin. Although lowering the voltage does make the display dimmer (until I get to 3.5v), my HD44780 needs between 0-1 volts on the contrast pin. Then again, my HD44780 is white letters on a black display, unlike this LCD.

Now that I think about it, this display probably came from the phone I garbage picked years ago. I threw away the case just a week ago though  smiley-cry
Maybe I still have the PCB. I'll go look for it.
187  Using Arduino / Displays / Re: Help identifying a scrapped LCD? on: March 16, 2012, 05:33:12 pm
Alright, so I tried comparing the LCD with one of my HD44780 displays and I believe that the pink pin is the contrast pin because my HD44780 has a very similar resistor bank connected to the contrast pin. Now I just need to find the main supply voltage pin and I should at least be able to get something on the display.
188  Using Arduino / Displays / Help identifying a scrapped LCD? on: March 16, 2012, 06:22:23 am
So, I found this 12 pin LCD/driver board in my scrap box recently and I need some help identifying the pinout. I have absolutely no idea what it came from and as far as I can tell it's a 16x2 4-bit parallel LCD, but I can't figure out what half the pins do. I took pictures and tried to outline all the traces etc. Dots in the middle or at the end of a trace respresent a via.










I'm off to bed now so sorry for the lack of information. If I remember anything tomorrow I'll post it.
189  Using Arduino / Displays / Re: LCD won't print the letter o? prints random garbage instead. on: March 11, 2012, 06:18:53 pm
Well what do you know, as usual the problem was caused by what I least expected. I had a bad connection from Vss and RW to ground. Re-soldered it and it works like a charm now. I'm still befuddled as to why the previously mentioned characters wouldn't print though and all others would. Generally, disconnecting RW and Vss would cause the display to be completely unresponsive, not half functioning in a predictable manner. If I follow my traces from Vss and RW it seems that there WAS actually a connection to ground, but it was through a 2k2 resistor... could that lead to a half functioning lcd? Either way, the problem is now solved. Thanks to every one for helping me solve it in under a day.
190  Using Arduino / Displays / Re: LCD won't print the letter o? prints random garbage instead. on: March 11, 2012, 05:56:28 pm
@floresta
1. backspace looks like a left arrow key, right next to 'o' in the link i posted

2. That's where things get confusing. Instead of printing a different character, the whole lcd goes blank and whatever I try to write after that becomes garbled, sometimes it prints a whole line of random characters, sometimes it prints 1 or 2 random characters. I'll if I can post a video to illustrate it more clearly.

3. Just tested with a multimeter, none of the pins are shorted to ground, Vcc, or each other. However, it seems that neither Vss nor RW have continuity to ground now... yet the lcd still works (other that my main problem of course). I'll go re-solder those and see what happens.
191  Using Arduino / Displays / Re: LCD won't print the letter o? prints random garbage instead. on: March 11, 2012, 03:38:28 pm
I thought it might be a timing problem. I'm using the defualt LiquidCrystal library, http://www.arduino.cc/en/Tutorial/LiquidCrystal . Nothing is connected to the data pins other than the lcd, and the traces are all less than 2 inches long. Unfortunately, I don't have any other (working) atmel micro's that I can test. I'll look through some HD44780 datasheets to see where I could add a delay between writes in the code. I might even go as far as cutting tracks/desoldering other components on my projects PCB to track down the problem.
What's driving me insane though is that it all works fine on a breadboard, and that it worked for two weeks until yesterday on my PCB.
192  Using Arduino / Displays / Re: Problem with connecting an LCD 16x2 on: March 11, 2012, 02:47:06 pm
where is led- connected to on your arduino. I see that you connected R/W to led-, when R/W should be connected to ground for writing. If you're powering the backlight off of a separate power supply, then rewire R/W to an arduino ground.
193  Using Arduino / Displays / Re: LCD won't print the letter o? prints random garbage instead. on: March 11, 2012, 02:23:10 pm
Alright it seems like I might be getting somewhere. After some more expirementing, it seems that I cant print the following characters: /, ?, O, _, o, and backspace. After looking at the character chart for an HD44780, http://inst.eecs.berkeley.edu/~ee40/calbot/webpage/lcd-ch1a.gif
 every single one of those characters is in the bottom row, with the last four bits being 1111. Not sure how this would relate to a connection problem though

@kenny the lcd works with my pin configuration on a breadboard, but not in my project.

@floresta I suppose so, but the thing is that the lcd worked for a week or two until yesterday.

@takao21106 as I've already mentioned, the lcd worked before, even in my project. The code isn't a problem either, as all example code fails to run if there is a character with 1111 as the last four bits

It would seem like a connection problem is the only thing left, but I can't figure out what would have to be disconnected for a character with 1111 as the last 4 bits not to print. I'm running in 4 bit mode btw, and I can print any other character, which would require all four data lines to have connection

EDIT: turns out I can't print any characters with the FISRT 4 bits as 1111 either. It still works fine on a breadboard though.
194  Using Arduino / Displays / LCD won't print the letter o? prints random garbage instead. on: March 11, 2012, 05:04:51 am
So I recently bought 2 16x2 lcd screens (1 as a spare), and hooked one up to the arduino. It worked fine with every sketch I loaded up on it so I started building my project. Long story short, everything worked as planned until today, when I was just finishing up the software.
For some reason, whenever I try to print the letter 'o', or a sentence with the letter 'o' in it, the lcd goes blank, the top row goes white, and anything I try to print after that will turn into garbage. Not even the hello world example works anymore. Originally, I thought the lcd controller was toast. However, it can't be an lcd problem because I get the exact same result on the backup lcd I bought. Then I thought that I had pooched the atmega328, and it was sending something else when I sent an 'o'. It can't be that either because the lcd will print the 'o' fine if I take it and the atmega328 out of my project and stick it on a breadboard. So naturally I then thought that I had a bad connection on a data pin, but there's no way I can achieve the same problem by unplugging data pins when the lcd is on a breadboard, I just get garbage no matter what I print, whether or not there's an 'o' in the sentence. So it's not an microcontroller problem (works on breadboard), it's not an lcd problem (works on backup lcd), and it's not a connection problem (unplugging data pins doesn't give the same problem). I'm now truly stumped as to what's causing this problem. Any ideas?
195  Using Arduino / Microcontrollers / Re: Can't upload sketches on freshly burned Atmega8? on: February 29, 2012, 11:40:49 pm
Ok, crisis averted. Turns out my TX and RX wires weren't soldered very well. Also, just for future reference, the 10k resistor from reset to Vcc is important. I couldn't upload without it.

EDIT: I do have another question though. Why does it take 9 seconds from the time I apply power for the program to start running? It's quite annoying and doesn't happen on my Uno.

EDIT 2: Also, I can't upload with arduino 1.0, but I can't compile my 1.0 sketches with arduino 0022.
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