Thursday, December 1
This Little Sword Letter Opener Will Slice Through Envelopes
A fire poker gets a new life as a sword-shaped letter opener.
The post This Little Sword Letter Opener Will Slice Through Envelopes appeared first on Make: DIY Projects and Ideas for Makers.
Learn the Lingo: Fine Leatherworking
Learn the common terms you'll need, in order to begin leatherworking.
The post Learn the Lingo: Fine Leatherworking appeared first on Make: DIY Projects and Ideas for Makers.
Craziest Pin-Saving LCD Trick Ever!
We love squeezing every last bit of silicon goodness out of a tiny chip, or at least we delight in seeing it done. Today’s analog/digital hack is one of the sweetest we’ve seen in a while. And it’s also a little bit of a puzzle, so don’t scroll down to the answer until you’ve given the schematic a good think-over.
[Claudio Larios] built a tachometer with LCD display, using only an eight pin PIC microcontroller for brains. (Translatrix.) Two pins are taken up by the power supply and one reads a Hall sensor, leaving only three pins to drive an LCD display which needs six signals. The problem to be solved is the fundamental mathematical issue that three is less than six. Now have a look at the schematic.
If you’ve not played with the Hitachi HD44780 LCD controller before, it has four-bit and eight-bit data modes. In four-bit, used here, you only need to send data on D4, D5, D6, and D7. RS selects between command and data mode, and E is the clock signal that latches the data in on a falling edge. Mull that over a bit before reading the next paragraph.
SPOILERS!
What [Claudio] is doing is essentially using the 10 nF capacitors as little memories! (Look into DRAM if this analogy seems a stretch to you.)
In a first pass, the PIC’s pins are set high or low for a longish period of time (500 microseconds), long enough to charge or discharge the capacitors through the 10K resistors. In a second pass, the values for D5 and D7 are set, and the E line is strobed up and down almost immediately to latch in the values on the no-capacitor lines.
The second pass happens so quickly that the capacitors can’t charge or discharge fully and RS, D4, and D6 read in whatever logic value was set during the first pass. Brilliant! (Oh yeah, this project was about a tachometer. We got distracted by the shiny pin-stretching tricks. We’re sure it’s a fine tachometer.) Did you see how he pulled that off with only three pins?! And no shift register?!?
HaD reader [danjovic] sent us the tip and did a little work on the code, verified that the technique worked, and provided the banner photos of his recreation. Many, many thanks!
Filed under: misc hacks
Geohot’s comma.ai Self-Driving Code On GitHub
First there was [Geohot]’s lofty goal to build a hacker’s version of the self-driving car. Then came comma.ai and a whole bunch of venture capital. After that, a letter from the Feds and a hasty retreat from the business end of things. The latest development? comma.ai’s openpilot project shows up on GitHub!
If you’ve got either an Acura ILX or Honda Civic 2016 Touring addition, you can start to play around with this technology on your own. Is this a good idea? Are you willing to buy some time on a closed track?
A quick browse through the code gives some clues as to what’s going on here. The board files show just how easy it is to interface with these cars’ driving controls: there’s a bunch of CAN commands and that’s it. There’s some unintentional black comedy, like a (software) crash-handler routine named crash.py.
What’s shocking is that there’s nothing shocking going on. It’s all pretty much straightforward Python with sprinklings of C. Honestly, it looks like something you could get into and start hacking away at pretty quickly. Anyone want to send us an Acura ILX for testing purposes? No promises you’ll get it back in one piece.
If you missed it, read up on our coverage of the rapid rise and faster retreat of comma.ai. But we don’t think the game is over yet: comma.ai is still hiring. Are open source self-driving cars in our future? That would be fantastic!
Via Endagadget. Thanks for the tip, [FaultyWarrior]!
Filed under: car hacks, news