Temperature logger

Thinking about a temperature logger.  Collect temperature data in the lab and outside for 1 week, with a timer attached. Then store temperature data and time on an external EEPROM.  I have a Sparkfun EEPROM and could use the arduino library for this EEPROM by initiating I2C protocol. Code for this EEPROM is available here, but make sure to read the comments to this blog for some critical changes.

Here is a microSD card shield that interfaces to bradboard/arduino, used by fat16lib in his post

Some arduino version with an LCD using I2C interfaces as a stand alone, and the code for reading and writing is loaded.  Second version attached to PC and uses Perl to log and plot.

Dumping data to excel is outlined in this thread

Programming arduino wirelessly using Xbee

Faludi wrote a beautiful tutorial on using XBees to program arduinos, and a wireless connection to the internet using xbee.

Upgraded Xbee - processing screen

Wireless for arduino

Wireless shield  from cutedigi.com for arduino $55, but would give wirless connection, with TCP/IP

Multiple RGB LEDS and expanding PWM controls

Increasing the number of PWM channels can use a TLC5940.  The arduino playground has some code, and an interesting thread. Digi-Key number 296-17732-5-ND, and the 28 PIN DIP is TLC5940NT and everyone is out of stock until Feb 2010 - must be a good chip!

Alternatives - could use multiple arduinos (each providing 6 PWMs) and use I2C to connect or maybe use an Arduino Mega (12 PWM).

analog gauges

Found some interesting analog gauges from old instruments and am thinking about interfacing them with arduino.  A good page on checking the series resistor (yes series) values to run them, and page on controlling with an arduino, so time to play with arduino or 5V...

PCB Boards

Perf boards, cheaper than Radio Shack and LadyAda uses them!!!! 21-113  are good small ones.
Then there are strip boards....

Controlling multiple LEDs

As ever tigoe has great information:

If you want discrete analog control over one output at a time, you can use a multiplexer. For digital control over multiple pins, you could use an addressable latch or a shift register. If you need pseudo-analog control over multiple pins, you could use a PWM driver.  There are also several LED driver chips that are designed specifically to control groups of LEDS.

So the ST16C596 shift register is similar to the popular 74HC595 shift register, but it’s nicer because it can sink a constant current to the LEDs it’s driving.