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1  Using Arduino / General Electronics / Re: Logic level MOSFET switch circuit on: October 01, 2014, 10:19:58 pm
You will probably be ok just directly connecting the gate to the Arduino pin, but a small resistor (say, 27 ohms) might be good to reduce any current spikes. If you have problems saturating the MOSFET you might want to use a second transistor to switch 12V directly to the MOSFET gate.

The MOSFET has a pretty hefty built-in reverse diode (110 amps peak) so you might not actually need an external diode.
2  Using Arduino / LEDs and Multiplexing / Re: Problem with NeoPixel 5mm RGB LED's on: October 01, 2014, 10:10:57 pm
If you swap the LEDs, does the problem stay with the second LED? If you switch them and now the first one stays blue...maybe it's a bad LED.
3  Using Arduino / Project Guidance / Re: Need help powering my project! Any pointers would be greatly appreciated. Thanks on: October 01, 2014, 10:08:38 pm
You most likely do NOT want to connect power rails together.

Rather than some complicated switching mechanism, you could make sure the GPS is always powered from the battery. Your connector simply has RX, TX, and ground.

It's probably safe to leave the serial pins floating, but if they're just TTL serial (no RS232 converter) it probably wouldn't hurt to use a weak (100K or so) pulldown.
4  Community / Products and Services / RGB LED Shades (wearable pixel matrix glasses) launched today on: September 25, 2014, 07:46:07 pm
They use WS2812B pixels and have an Arduino-compatible controller (FTDI included, board type Arduino Pro Mini 5V/16MHz). Really bright, and a lot of fun to program and wear.
5  Using Arduino / LEDs and Multiplexing / Re: MCP23017 Causing Arduino to become unresponsive on: July 14, 2014, 07:20:46 pm
Problems with I2C can cause the Arduino to stop responding. This should have been minimized in 1.0x versions of the Arduino IDE. However, you will want to check your pullup resistors, SDA/SCL connections, etc.

I have a board that uses the MCP23017, and I created a library to go with it. You can easily use the same library with a self-built MCP23017 circuit:

You're also using a custom shift out function, but there's a canned shiftOut routine already...that might be causing problems.
6  Using Arduino / LEDs and Multiplexing / Re: Addressable WHITE led strip on: July 14, 2014, 07:16:21 pm
There are white LEDs in 5050 size, with three separate white chips. You could (in theory) take a strip that has controller chips and RGB LEDs, remove the RGBs, and install the white LEDs. It wouldn't take any less data, though.
7  Products / Arduino Due / Re: Due multiplexer shield on: July 13, 2014, 01:08:06 am
The Centipede Shield will work at 3.3V. There is a power jumper that either connects the 5V supply to the shield, or an AUX+ pin. You would need to solder a jumper wire from AUX+ to the 3.3V power pin on the shield. Additionally, the I2C pin locations on the Due are not the same as the Uno-style Arduinos. You would need to run jumper wires from A4 and A5 on the shield to the correct I2C locations.

It might be easier to simply not solder in the pass through headers, mount the Centipede Shield elsewhere, and just run 3.3V, GND, SDA, and SCL over to the shield from the Due.
8  Using Arduino / Programming Questions / Re: Setting system to use time32 (new timelord lib) w/ a DS3231 Chronodot RTC on: July 11, 2014, 11:27:57 pm
Here's an example using the ChronoDot with time.h...I haven't tried time32, but the time structure should at least be similar. I hope it helps...

Feel free to use the macetech contact page to alert me to any Arduino forum posts dealing with macetech products, I don't mind solving problems here.
9  Community / Products and Services / LED Matrix Shades in stock again, discounted on: July 10, 2014, 09:21:54 pm
I have more of the LED Matrix Shades in stock. They use AS1130 matrix LED drivers chips and have an integrated Arduino-compatible. The code is available and can be hacked to your heart's content, and there are some digital and analog lines brought out for hardware hacks. There was a silkscreen error on the front, so they're discounted way below normal pricing.

10  Using Arduino / LEDs and Multiplexing / Re: Arduino RGB LED Strip Audio Visualizer on: July 09, 2014, 11:36:19 pm
If you can manage the interface between the Arduino and the LED strips, here is an example of using Processing to monitor audio and pass pattern commands to an Arduino. The links to the code are about halfway in:

The key is that you want to use Soundflower to create a virtual audio output device on your Mac, which can be piped both to your Processing sketch and your speakers. No mic involved. On Windows this is usually easier since you can use the Stereo Mix device.
11  Using Arduino / LEDs and Multiplexing / Re: LED signature on: July 09, 2014, 11:32:39 pm
I've seen this effect done with fiber optics poked through holes drilled in a panel, and the other ends arranged around a slowly rotating wheel that selectively blocks light. You could source a lot of the materials from places that sell supplies to build starlight ceilings.
12  Using Arduino / Project Guidance / Re: looking for an arduino like board with monitor hdmi / svga on: June 20, 2014, 12:50:16 am
I knew that the options I posted were close...and there are others too (PICASO for example) that get close but don't meet every single specification you posted. The reason I went ahead and linked them is because when you're in the specification stage of your project and haven't built anything yet, you need to have some flexibility and make some tradeoffs. You don't want to use a Raspberry Pi, BeagleBone (unavailable), pcDuino, Arduino Tre (unavailable)....then accept lower resolution and use an Arduino shield. Or if it's absolutely mandatory that you must have 800x600, get rid of the Arduino and figure out how to make something else work.
13  Using Arduino / Project Guidance / Re: looking for an arduino like board with monitor hdmi / svga on: June 19, 2014, 04:24:17 pm

Guys. PGT asked for some way of sending output to a monitor without using an operating system. It's counterproductive to imply that PGT is stupid for wanting this, when solutions exist:

Arcade Shield:

I'm sure there are others.
14  Using Arduino / Project Guidance / Re: Music Visualizer Project : Extracting data from computer's audio buffer on: January 20, 2014, 01:41:28 am
Nice writeup about your progress...if you keep up this habit, you'll definitely go far! smiley
15  Using Arduino / LEDs and Multiplexing / Re: trouble getting WS2812B working on: January 17, 2014, 05:30:28 pm
I have used the four-lead WS2812B LEDs and they work fine with the existing code. You might have some that are set to 400KHz instead of 800KHz, or otherwise configured differently. I would check all the connections with a multimeter, and try to make sure you haven't accidentally given them 12V from that supply.
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