vrijdag 10 augustus 2012
The Tweeting cat III
The new version uses a LiPoly battery, which outputs 3.7V. Since the 33V requires 4.6V input, I left that circuit untouched, and instead moved the 3.7V from the LiPoly battery into a 5V DC to DC Step Up circuit. The resulting circuit is a lot smaller (as you can see in the picture). Initially there was a problem with the circuit not working, but it turns out that there is an open (and unsoldered) jumper that disables the entire thing. After moving the battery connector to this jumper and adding a ground wire the thing worked fine.
I hooked it up and it also notified the laptop when Nephthys was eating, I even got three messages, each time she lowered her head to the food bowl. The next step is to write the playstation 2 code, where I'm planning to just have cu (the terminal emulator) running in the background writing to a file, which the pike application will read from and send messages to ttyter which sends them to twitter. I decided to stick with cu, because despite my device driver coding the USB system is still quite unstable, and opening and closing the port repeatedly (which will happen if I start writing my program for it) could cause it to crash.
Another aspect is charging the LiPoly battery, I have a circuit for that but it gets rather hot (mostly because my input voltage is 12V). I'm looking for a more efficient input, but probably will use a USB port for this.