Motion Tracking On The Cheap With A PIC

February 13, 2014 by James Hobson 8 Comments

motion tracking

Ever need a cheap motion tracker for very basic object following? Did you know you can throw one together with a few IR distance sensors and a PIC?

The setup is fairly simple. [Aron Horan] is using a dsPIC30F4011 PIC, a SHARP infrared distance sensor, an RC servo, and a PICkit2 for testing. It works by scanning left and right using the servo motor. When the edge of an object is detected, it will turn away from the object until it can no longer detect the edge — then it turns back. Unfortunately this does mean it will always be twitching, even when it’s tracking an object.

Like many of the other projects [Aron] has documented, he’s included everything you need to know to be able to recreate the project yourself. Flowcharts, wiring diagrams, and the code — written in C of course! The following video includes an excellent demonstration, but if you want to skip straight to the action, you can see it start tracking a multimeter at about 0:39 in.

Continue reading “Motion Tracking On The Cheap With A PIC” →

Java Grinder Spits Out DsPIC And MSP430 Assembly Code

February 10, 2014 by Mike Szczys 13 Comments

java-code-grinder

[Michael Kohn] sent in a link to the set of projects he’s been working on lately. The Java Grinder is a project that converts Java code for use on microcontrollers. This actually started back in 2009, when he mentioned that the project was worthless because there were already a ton of Java virtual machines out there. But if he had really thought that he’d never learn anything. We’re glad [Michael] picked this back up and made something out of it.

The image above shows the proof of concept. It’s a box bouncing around the Nokia 6100 screen. He wrote the animation in Java, and used his grinder to turn the code into dsPIC assembly, which was then compiled and flashed onto the microcontroller. That’s not all, he’s also coded a Mandelbrot set generator or the same hardware. As it stands he can also produce assembly code for use on MSP430 chips.

This kind of exploration is great for the brain. We see it as a natural extension of the learning you acquire from Nand2Tetris which walks through the essential text The Elements of Computing Systems. If you’re not familiar, that’s a trip from building your first logic gate, which you plunk together with others to build an ALU, then start coding all the way up to a virtual machine to run on your simulated hardware.

Video of the bouncing box and Mandelbrot set is below.

Continue reading “Java Grinder Spits Out DsPIC And MSP430 Assembly Code” →

Single Digit Numitron Clock

February 9, 2014 by Marsh 17 Comments

The above may look like a Nixie tube, but it’s a Numitron: the Nixie’s lower-voltage friend, and part of [pinomelean’s] single-digit Numitron clock. If you’re unfamiliar with Numitrons, we suggest you take a look at our post from a few years ago, which includes a helpful tutorial to catch you up to speed.

[pinomelean] built this little device to capture a steampunk-ish look on the cheap for a clock small enough to fit on a wrist. The build uses a PIC16F84A uC and a 4MHz crystal on a custom PCB. A small button on the side lets the wearer set the time. Similar to the Vibrating Timepiece from last month, the Numitron clock isn’t perfect, though it is more accurate: gaining only one minute every 3 days.

Check out the video after the break to see it being set and keeping track of the time. It may take a moment to understand how to read the clock, though. Each of the four LEDs indicates where the number in the Numitron tube belongs. The LEDs light in sequence from left to right, displaying the clock one digit at a time.

Continue reading “Single Digit Numitron Clock” →

Mario Doorbell Guaranteed To Drive A-You A-Crazy

February 9, 2014 by Marsh 8 Comments

marioDoorbell

Is your doorbell not exciting enough for your guests? [Joe] wanted to provide a little entertainment for his visitors, so he redesigned his doorbell with a Mario theme.

Whenever someone presses the button—which carries the Mario coin image—the segment display increments and the Mario coin sound plays. To add variety, the life-up sound plays at every 10 coins and the mushroom upgrade sound plays upon reaching 100. [Joe] tried putting the life-up sound at its appropriate 100’s place and the mushroom sound at every 10, but he decided the brevity of life-up was more tolerable in the 10’s slot.

The project was divided into two components. The door button has a PIC16F628A microcontroller with a dual 7-segment LED display, a button, and a homemade circuit board. All this lives in a simple box covered by a Yoshi’s Island-themed decal. The button’s board connects to a separate ringer board—based around a PIC16F87—with a MCP4822 DAC and a 25LC1024 EEPROM. Button presses on the first board prompt a request for a sound clip read on the EEPROM. Keep clicking for a demo video below.

Continue reading “Mario Doorbell Guaranteed To Drive A-You A-Crazy” →

Tic Tac PIC Pack: A Pocket Programmer

February 5, 2014 by Kristina Panos 10 Comments

Sure, mint tin housings are great. But you have to defend against shorts, and cutting out holes for ports and buttons is dangerous business. [Daniel] prefers plastic, and he tipped us off about a PICKit2 clone that he designed to fit inside of a tic tac box.

Almost all of the components were salvaged except for the microcontroller and the connectors. He wound his own inductor using the ferrite core from a CFL. [Daniel] had to make a few improvisations for this project. He didn’t have a 20MHz crystal, so he used a 12MHz crystal and tweaked the fuse bits after burning the firmware.

To save space on the board, he soldered wires to RESET, VCC, GND, PGD, and PGC to program the firmware and then removed the wires. The only trouble he had with it was more or less easily solved by replacing two transistors.

You may remember that we linked to his USBasp programmer in a mentos container a few months back. We figure [Daniel] must have some pretty fresh breath.

WS2811 SPI Driver Using One Transistor And Passives

February 4, 2014 by Mike Szczys 6 Comments

ws2811-spi-driver

We love the WS28xx projects because even if we never plan to use them, the signal timing is like the most addictive puzzle game ever. For instance, check out this WS2811A driver which uses hardware SPI to generate the signals.

The WS28xx offerings place a microcontroller inside an RGB LED, allowing them to be individually addressed in very long chains or large matrices (still a chain but different layout). But the timing scheme used to address them doesn’t play well with traditionally available microcontroller peripherals. [Brett] had been intrigued by some of the attempts to bend hardware SPI to the will of the WS2811 — notably [Cunning_Fellow’s] work featured in this post. He took it a great step forward by simplifying the driver to just one transistor, three resistors, and a capacitor.

Click through the link above for his step-by-step description of how the circuit works (it’s not worth re-explaining here as he does a very concise job himself). The oscilloscope above shows the SPI signal on top and the resulting timing signal below. You will notice the edges aren’t very clean, which requires the first pixel to be very close to the driver or risk further degradation. But, since the WS28xx drivers feature a repeater which cleans up signals like this, it’s smooth sailing after the first pixel.

A Better USI I2C Library For The MSP430

February 2, 2014 by Brian Benchoff 7 Comments

USI

TI’s MSP430 chips are rather interesting – they’re low power, very capable, and available for under a dollar in most cases. Some of these chips, though, don’t have native SPI or I2C interfaces; instead, everything is done through a USI, or Universal Serial Interface module. [Jan] found the stock I2C USI module was a little rough around the edges, so he created his own.

[Jan] found the TI example code for using the USI as an I2C device overly complicated and something that an intern whipped up in a week and was never touched again. In response to this, he created a much, much simpler USI/I2C module that’s actually readable. It’s available over on the GitHub if you want to grab it for yourself.

Compared to the TI code, [Jan]’s library is dead simple. There are only two functions, one for initialization, and another for sending and receiving. Easy, small, and it works. Can’t do much better than that.