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181  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.
182  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.
183  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.
184  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.
185  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.
186  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?
187  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.
188  Using Arduino / Microcontrollers / Can't upload sketches on freshly burned Atmega8? on: February 29, 2012, 10:07:11 pm
So I bought an Atmega8 with no bootloader on it. I uploaded the ArduinoISP sketch on my Uno, and hooked it up to my Atmega8 like this: http://arduino.cc/en/uploads/Tutorial/BreadboardAVR.png
Then, in Arduino 0022, I selected the "arduinoNG w/ Atmega8", and clicked burn bootloader > w/ arduino as ISP. After A few seconds I got the message that it was done. Problem is, I can't upload upload any sketches to the Atmega8. I'm using my Uno as a USB to serial converter, and hooking up the reset, TX, and RX pins to the Atmega8 like this:
http://arduino.cc/en/uploads/Tutorial/ArduinoUSBSerial.png
After selecting "arduinoNG w/ Atmega8" and pressing upload, all I get is the occasional rapid blinking from an led I hooked up to pin 13 and this error message from Arduino 0022 "avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51"
I'm trying to load the blink sketch. Any ideas? I'm new to all this bootloading stuff so I'm really surprised i even got this far.
189  Using Arduino / Project Guidance / Re: Is it necessary to connect all GND's and VCC's on a standalone board? on: February 17, 2012, 03:05:39 am
@winner10920 It's a hand drawn (with a sharpie as resist ink), home etched board, so using a TQFP is hard enough as it is and the less traces I have to run to the IC, the easier it will be to draw the board.

@Techone I decided to build up a breadboard arduino with a DIP atmega328, just to be completely sure. It seems, however, that I only have to hook up one GND and one VCC pin on the chip in order to get it to work, so I assume all the extra GND and VCC pins are internally connected together. Have you experienced any problem by not connecting all the power pins? Or is the atmega8 different in some way?
190  Using Arduino / Project Guidance / Is it necessary to connect all GND's and VCC's on a standalone board? on: February 16, 2012, 07:08:29 pm
So I'm working on my first standalone board with an IC on it, in this case an atmega8 in a TQFP-32 package. I was wondering if it's absolutely necessary to connect every single VCC and GND pin on the IC, or if I can just hook up whichever power pins are most convenient. In my case it would be really nice if I only had to hook up one VCC and GND pin, as it would save the frustration of trying to hook all the power pins together.
191  Using Arduino / Displays / Re: Which LCD display should I buy? on: February 02, 2012, 07:11:00 pm
Wow, thanks for the info Bill, I could only find the HD44780 for $20 with another $20 shipping to Canada before this! Tayda Electronics also seems like a great place, with only $2 shipping. I guess this is the way to go.
192  Using Arduino / Displays / Re: Which LCD display should I buy? on: February 02, 2012, 03:38:55 am
Well it seems that you're the opposite of me  smiley-grin  Being only 14 and pressed on money, I'd much rather get the cheaper parallel display and add a shift register, although I had considered doing serial originally. Plus it will be a learning experience, as I've never used a parallel device. Luckily time isn't an issue either for this project.
193  Using Arduino / Displays / Which LCD display should I buy? on: February 02, 2012, 02:20:16 am
So, there seem to be hundreds, if not thousands, of LCD's available. I've narrowed it down to about 30 so far and I need help picking the right one for projects to come. Any one of these:

http://ca.mouser.com/Optoelectronics/Displays/LCD-Displays/LCD-Character-Display-Modules/_/N-6j737?P=1z0ypn7Z1z0wsxbZ1z0wrxyZ1z0wry3Z1z0wrxtZ1z0wry2Z1yzxq7eZ1yzuuf6Z1z0wtzzZ1z0wsy4Z1z0wrybZ1yzuuf7Z1z0wry1Z1z0wrxsZ1z0wrxzZ1z0wul9Z1z0x81tZ1z0wumiZ1z0wuleZ1z0wukmZ1z0wula&Ns=Pricing

should work just fine (I only need character display), but I'd like to know if any of you have had problems with them, or can recommend a better one. I'm buying a bunch of 74HC595 shift registers as well, so arduino pin count shouldn't be an issue (only have 5 pins left!).
The display must, therefore be parallel. 16x2 minimum.
Currently I'm thinking of getting this one:

http://ca.mouser.com/ProductDetail/Newhaven-Display/NHD-0216BZ-RN-YBW/?qs=sGAEpiMZZMt7dcPGmvnkBncbWZknnCVih0jgiiLJclA%3d

as it's the cheapest one, although poorly documented.
All suggestions welcome as I can only pretend to know what I'm talking about when it comes to LCD's
194  Using Arduino / Motors, Mechanics, and Power / Re: How to stop a stepper motor from holding/locking? on: December 23, 2011, 01:20:19 am
Alright, sending a LOW with digitalWrite() to every pin on the h bridges seems to do the trick (didn't work the first time I tried though...) , I guess I'll hook the big power supply back up and hope it all works.
195  Using Arduino / Motors, Mechanics, and Power / Re: Connecting ground of arduino to ground of power supply? on: December 22, 2011, 02:17:04 am
yes
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