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301  Using Arduino / LEDs and Multiplexing / Re: First LED matrix on: February 22, 2012, 01:32:57 am
You don't specify what chips you're using so I can't comment directly on your setup but a 16 MHz 328 runs my 24x16 matrix with 32 levels of PWM with no problems, so what you want to do is absolutely doable.

Good luck!
302  Using Arduino / General Electronics / Re: Solder paste for stencils on: February 21, 2012, 11:31:48 pm
It looks like it's the paste...I tried with the leaded solder and got good results (attached). Time to find some new lead free paste that hopefully isn't $500 for shipping.

Now to figure out how to place the FTDI chip without smearing the paste...

303  Using Arduino / General Electronics / Re: Solder paste for stencils on: February 21, 2012, 07:16:20 pm
The footprints for the rest of the parts (SOIC, TQFP, 1206, 805, SOT-23) look like they'll work, it's just the fine-pitched FTDI chip I'm having problems with.

The stencil is a Pololu 4 mil Mylar sheet. I think the alignment looks fine with the stencil on top of the board; I will try to take a pic if you think it will help.

The paste was filled Sept 2 2011 and I just opened it today; it's been refrigerated since I got it last fall. It was out for about an hour before I started; I'll leave it out a few more hours. It's slightly runnier than the lead paste I usually use but I thought that was due to the difference in metals.

I will definitely keep practicing; thanks for the tips.

304  Using Arduino / General Electronics / Solder paste for stencils on: February 21, 2012, 06:34:51 pm
I have a syringe of this:

I'm having trouble getting a clean stencil mask for a FT232RL chip. Is this the wrong kind of solder paste for a stencil? If so, does anybody have any recommendations?


305  Using Arduino / LEDs and Multiplexing / Re: Ledstrip not evenly coloured on: February 21, 2012, 04:54:24 pm
It sounds like you're using RGB LEDs? How are they wired up? How many LEDs? Is the color shift change gradual across the string or is it abrupt? If you reverse the LED string does the problem stick with the LED ends or the near/far ends?
306  Using Arduino / General Electronics / Re: arduino project prototype conversion to final product on: February 21, 2012, 10:52:56 am
What is the best way for me to get my cool project off of the Uno and onto my circuit board?

You could use the Uno as a programmer:

(ignore the part that says the Uno doesn't work for this - it's outdated)

Can you point me to some directions which list the components necessary to run a ATmega328 based circuit?

Note that you may not need all of the components; e.g. If you're using a specific, regulated power supply you may not need the 7805.

307  Using Arduino / General Electronics / Re: How do you interface arduino to 3.3V input pin? on: February 20, 2012, 11:44:11 pm
If it's 1s and 0s then I think the voltage divider will be fine. I've been using this setup to interface a WiFly serial module with a Duemilanove, Nano, and custom 328 board for a few weeks now with no problems. I confirmed via voltmeter the 5v output from the gets reduced to 3.3v.
308  Using Arduino / Programming Questions / Re: lcd.print(var, BYTE) no longer supported... on: February 20, 2012, 05:34:34 pm
lcd.write() ?
309  Using Arduino / General Electronics / Re: Maximum current in wires. on: February 20, 2012, 05:22:01 pm
Do I need special wires for that ?


What would be the minimum diameter of the wires ?

Depends on the distance. Don't forget "distance" is the full loop, not just from the power supply to the LED. See this table:

Good luck!

310  Using Arduino / Microcontrollers / Re: ATmega1284P: End to End using 1.0 IDE on: February 20, 2012, 05:06:47 pm
I can't help you with the 1284p, but the pins_arduino.h is already done for the 32u4 in hardware / arduino / variants / leonardo of the Arduino install folder.

311  Using Arduino / General Electronics / Re: How do you interface arduino to 3.3V input pin? on: February 20, 2012, 03:00:09 pm
I stole this from Grumpy Mike:

Connect a 1.8K resistor from the Arduino pin to the 3.3V input pin

Connect a 3.3K resistor from the 3.3V input pin to ground

In other words, this:

with Z1 = 1800 ohms & Z2 = 3300 ohms

Good luck!

312  Using Arduino / Project Guidance / Re: Help needed in making LED Cube on: February 19, 2012, 03:05:41 pm
There's infinity LED cubes on the web; I don't think I'd be able to improve on them so I won't try, but:

Will it be possible to get the code permanently written on a Micro controller chip so that I can properly case the cube n make it permanent. (I ask this question because I know you can make a copy of chip using the UNO but I have a Mega ADK having a Mega2560 and would like to know if it is possible to make a copy of the project on a smaller chip ie: ATMega 128, 328 etc. )

As long as you don't use more IO pins, Flash, or RAM than the 128/328 has, then yes you can transfer it. Once your project is done you can get a blank chip and burn the bootloader and/or sketch to it, basically you're looking to do this:

Note that you may not need all of those parts -- for example if you're using an external regulated power supply you won't need the 7805.

Good luck!
313  Using Arduino / Project Guidance / Re: Arduino for modifying resistance values on: February 17, 2012, 11:29:46 am
#2 and 3 are easy using the map() function:

e.g. map(analogRead(A0), 0, 1023, 50, 500);

The only way I know to do #4 is with a digital potentiometer:

but I'm sure others on the forum will have better ideas.

Good luck!

314  Using Arduino / Project Guidance / Re: No response any ideas? Grove camera on: February 17, 2012, 10:18:29 am
Sorry, if you've used their diagnostic tool I can't think of anything else to try. I'd contact Seeed at this point and see if you have a bad device.

It looks like a cool product; hope you get it resolved.
315  Using Arduino / Project Guidance / Re: No response any ideas? Grove camera on: February 17, 2012, 10:02:56 am
You mean pins 0 and 1, not pins 1 and 2, right?
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