Posts Tagged Arduino
Wifi Enabled RGB Matrix Wall Light, Part 1
Posted by cg in Making and Tinkering on December 17, 2011
Inspired by the so called Lampduino and several other related projects I decided to build my own version of a RGB matrix wall light some time ago. During the last few weeks I finally managed to start out on this project.
Hardware
The matrix of 64 individual cells and the LED back-plane are made from 4mm thin plywood that I spray-painted with a silvery varnish. The outer frame is made from a stronger 14mm birch multiplex board, yielding a very solid construction. I also bought some thin, white PVC board intended as the material for the front cover, but I still have to figure out how to cut that nicely.
Lacking the ambition to create my own LED driver board I settled for the “Rainbowduino”, an Arduino compatible board developed and sold by Seeed Studio. In addition to that, I wanted the matrix to be controlled and programmed over the air. One of the cheapest, easiest, and most versatile ways to accomplish this was to modify an OpenWRT based router for this purpose.
Serial Communication Between an Arduino and the TL-MR3220 Router
Posted by cg in Making and Tinkering on September 25, 2011
Last time, I installed OpenWRT on the TL-MR3220 router and added a connector for it’s serial interface. Today, I wanted to try and connect this interface to an Arduino to make the two communicate. The router’s interface operates at 3.3V while the Arduino’s UART operates at 5V, so we need to convert between those levels. The cheapest way to do this that I could find is described here. It involves using a 74LS04 hex inverter chip to convert the 3.3V signal up to 5V and two resistors for a simple voltage divider to convert the 5V signal down to 3.3V.
Seeeduino Stalker: Writing to the SD Card
Posted by cg in Making and Tinkering on August 16, 2011
After I managed to upload the first sketches to the Seeeduino Stalker last week, I was eager to try the special features offered by this special kind of Arduino platform. 
I decided to try writing to an SD card first and followed the example included in the Stalker’s documentation. Which turned out to not work at all.
A couple of hours later and looking for errors in all the wrong places, I finally managed to find out how to use the FileLogger library:
- The SD card needs to be FAT16 formatted.
- The file that the the Arduino is writing to must exist, the library does not create files.
- The file must not be empty, it must contain at least one byte of data.
If these conditions are met, the following tiny sketch will work just fine and append data to the file:
#include "FileLogger.h"
void setup(void)
{
byte buffer[] = "Hello World!";
FileLogger::append("data.txt", buffer, 12);
}
void loop(void) {}
Update 10/8/12: Please note that this example will work with version 1.0 of the Stalker, only. For newer versions of the board you should try sadfatlib.
Connecting to the Seeeduino Stalker
Posted by cg in Making and Tinkering on August 7, 2011
A few weeks ago, Seeed Studio were celebrating their anniversary with a bunch of limited offers. Among other things, I acquired a pair of Seeeduino Stalkers v1.0 with an Atmega 168. Unfortunately, the serial interface on those boards is not labeled. So it took me a while to figure out how to connect the FTDI breakout board. With a small adapter board, programming the Stalkers with the Arduino IDE now works like a charm. (Select board type “Duemilanove w/ 168″.)
