Thursday, June 5, 2008

My Free Samples are Coming

So I've been looking around for projects to use the I2C interface on an Arduino, and requested a few ICs from some chip makers. Half to my surprise, what they say about getting free samples is true.
  • I ordered a AT24C256B and AT24C1024B from Atmel. These are EEPROMs, which allow me to store data between power cycles. The Arduino comes with 512 bytes of EEPROM, but you never know when another 32k + 125k might come in handy. I haven't heard anything from them, but assume the samples have shipped and may already have arrived in Sunnyvale.
  • I ordered a DS1721 thermometer/thermostat from Maxim. Of all the ICs I've order, this one is probably the one I'm most excited about. Not only can you read the temperature off the IC, you can also set a high and low temperature. This would be useful if you wanted to use it to monitor the temperature in a case and control a cooling fan. You could set it to latch on at 60 degrees and turn off at 45 degrees. Maxim emailed me the next morning and said it had shipped.
  • Lastly I ordered a PCA9555DWR digital I/O breakout from TI. This chip will be useful if I ever decide to run more than 14 LEDs or switches. The chip pretty much just adds 16 I/O pins to run anything off of that you would normally run directly off the Arduino. One nice thing about this chip is that it has pull-up resistors built into the IC, so running switched or buttons on it will be trivial (This is because a floating I/O pin will give erratic readings if it isn't pulled to high or low).
Now I just need to buy my Arduino and get working on a temperature logger. I'll have enough ROM to record the temperature every 5 minutes for more than 18 months.

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