Hack-Ready Alarm Clock

The project has now been updated to the latest Raspian release! I tested this on Raspian Minimal, but it should work on NOOBS as well.

I'm still hacking away at the Hack Clock. I've had several teaching sessions now and found some bugs in the process - as well as some incorrect assumptions.

I had thought kids would be interested in the weather station aspect of the clock - but the thing they wanted the most was to press a button and have a music playlist start playing. I'll likely re-do the lessons likewise... instead of teaching I/O and buttons with the weather station, I'll hook in the music right away.

Since there has been a big emphasis on the sound of the clock, I also found several audio bugs I needed to squash. I also added playlist support as a way to teach arrays and lists.

I also need to write routines for automatic saving of changes and ways of automatically backing up the event loop source file. Students should feel free to experiment - so I need to make it safe to do so.

Also adding support for the 2.8" PiTFT... so high-res(ish) screens are in the near future.

Tutorials, instructor guides and some initial lessons are now posted to http://hackclock.deckerego.net/. The site isn't exactly pretty... but I'm making sure I get the content out as soon as possible. UI/UX will come after bit - the biggest priority was getting things out before the Hour of Code week is over!

A big question in my mind for a while was how you could easily allow people to edit the clock's main run routine. I didn't want to make editing the Python file containing the main event loop difficult - it should require no installation and be fairly apparent. I didn't want to have to teach kids to SSH into the console, as laudable a goal as that might be.

After looking at a few JavaScript code editors, I think I've settled on CodeMirror as a way to expose the main run routine in an HTML page, which can then be edited easily within a browser. This meant I had to convert the project to Bottle, and I'll need to build some elementary parts of the code editor. In the end there should be a web interface to upload audio, edit the main event loop and safely re-start the clock driver without fear of runtime or compile time crashes.

The hardware build itself is almost complete, so next up will be getting this clock IDE running.

My attempts at trying to build my own mono audio amp using an NTE823 were not fantastic... I think I either misinterpreted a pull-down resistor on the schematic or messed up the capacitor arrangement, but within a minute or so I started to smell the oh-too-familiar "oh crap the IC is burning" smell. It was pretty dang hot to the touch, so I ripped it out before major damage was done.

Instead of building another infamous LM286 amp, I decided to browse Adafruit and see if they had an easier to use breakout board. Sure 'nuff, they had one for about half the individual component cost. Minus one point for my electrical engineering skills, plus one point for Adafruit already doing the heavy lifting for me. I'm going to change my parts list for the project to use the mono amp from Adafruit instead.

The seven segment Python display library needed some cleaning up - the indicator lights on the display were either all on or all off. The ClockDisplay library now will set each of the four indicators individually, so the app running the clock logic should be much more simple.

The actual time display is running fine now, moving on to audio output. After "alarm clock" functionality is created by piping audio out at a specified time, I'll work on the enclosure.

Trying out the audio amplifier Instructable at http://www.instructables.com/id/LM386-Audio-Amplifier/ - also picked up an NTE823 from Fry's (the equivalent of the LM386) to see how well we can amplify the audio just using the 5V+ GPIO pin and the headphone jack.

It appears that Adafruit's I2C Python libraries haven't been updated to work with the A+ and B+ Raspberry Pi's. Just created a pull request to get things to work again, and will manually commit it to the project's GitHub repo: https://github.com/adafruit/Adafruit-Raspberry-Pi-Python-Code/pull/100