Imablog

January 12, 2015October 13, 2024

Si5351 breakout board

Jason/NT7S launched the crowdfunding campaign for his version of an Si5351 breakout board last night, and already this morning it’s at over 150%. The stretch goal at $1 500 involves spending some more time on the software library to make the board easier to use.

It’s a neat little oscillator chip that seems to provide a lot of capabilities for not a lot of money. He’s been documenting his investigations on the chip at his blog for the past year now, including building a couple of receivers and transceivers around the Si5351.

The Si5351A is quite a capable IC at a very modest price. It is a PLL clock generator with three independent outputs which can each generate a separate signal from 8 kHz to 160 MHz. A 25 or 27 MHz reference oscillator is used for the two internal PLLs (the Etherkit breakout board uses a 25 MHz reference oscillator), which allows the user to choose the amount of frequency stability and accuracy required.

Go check out the Si5351 breakout board campaign on Indiegogo, and pick one up if it’s something you’ll find useful in an upcoming project.

January 9, 2015

Birthday slippers

To go with my robe!

January 1, 2015

Happy New Year from the dogs and cat

We didn’t make it out to the beach today (I stayed home to do the Lord of the Rings marathon), so Nala and Simba (and I) are wishing everybody a Happy 2015 from the back yard.

Mischief prefers to wish everybody a Happy New Year from the comfort of her futon.

December 25, 2014October 13, 2024

Arduino thermometer

Started with my first big Arduino project using one of the Sparkfun Redboards and my new *duino work station.

The Adafruit RGB LCD shield and TMP36 temperature sensor were pretty easy to wire up to the Redboard. The LCD shield communicates using the I2C pins, so it just need those to connections plus 5V power and ground from the Redboard. The TMP36 was just as easy to wire using 3.3V power and ground from the Redboard and connection to one of the Redboard analog inputs.

Fritzing schematic illustrating connections from a Sparkfun RedBoard, an LCD display module, and a TMP36 temperature sensor

(There was no Fritzing part for the LCD shield, so I just used an LCD display part instead)

A few hours of writing some code and fiddling around got me a working thermometer.

Sparkfun Redboard connected to a breadboard containing an LCD display module

Thanks to the Adafruit RGB LCD library, the sketch for what I’ve done so far is pretty simple. Pressing the Select button on the shield makes the LCD turn on and display the current temperature as well as the range of temperatures measured since it was turned on. The temperature is displayed for 30 seconds, then the LCD and backlight are turned off. Pressing the Select button again makes it display the temperature again.

The next step will be to add some additional functions accessed via a menu. I’ll add a speaker or buzzer and have it alarm above a certain temperature. Once I have this prototype working nicely, I’ll repackage it and turn it into a thermometer to monitor the temperature in our freezer. I’ll have to figure out how to attach the thermometer to the power and analog pins, because the LCD shield doesn’t break them out. Shouldn’t be too hard to work out.