Looking at the looping GIF above you’re probably thinking, oh, another hard drive POV setup… Well… Not quite.
This is one of [Dev’s] latest projects, and it is a planetary map that shows the angular positions of all 8 of the major celestial bodies from any given date between 1800 and 2050. It’s also capable of showing analogue clock hands, the phases of the moon, and other simple graphics.
The main unit is a hard disk, but [Dev] milled off many of the features on it to give it a more exposed, purpose-built look. He designed the LED bearing PCB from scratch using EagleCAD, which sits on the back of the drive, with the spindle poking through. It has 8 rings of 5 surface mounted LEDs, which shine through opaque plastic diffuser rings that he printed using Shapeways — they feature small recesses to fit snugly on the board over the LEDs. On the top level is a 1mm thick black disc of some unknown material that [Dev] had sitting around, which now has 8 holes machined into it in the exact position of the LEDs.
A Cortex-M0 drives the LEDs using an LPCXpresso board which allows the LEDs to sit across only one byte of a hardware I/O port. On the software end, each rotation of the disk is segmented into three hundred and sixty 1 degree slices. This system allows him to achieve a circular resolution of 8×360 pixels at 25 frames per second. Not bad for a persistence of vision device!
Stick around after the break to see the rather entertaining demo video of the device.
Continue reading “Persistence of Vision Planetary Map”
[James Lynch] picked up an LPCXpresso board because he wanted play around with ARM processors. The board, which is shown on the right, provides everything you need to get started. It even ships with a free IDE. But unfortunately the free version of that Code Red IDE is size limited. If he wanted to remove the restriction he would have to pony up $999 for a licensed version. A company might not think twice about this payment, but in the hobby realm that’s simply out of the question. Instead, [James] figured out how to use the CooCox programmer with the LPCXpresso hardware. To get at his 59-page guide on the process follow that link and hit the “Download Zip” button in the lower right for a copy of the PDF file.
The hack comes in two parts. First you need to alter the LPCXpresso board. There is a center line that separates the dev board form the debugger/programmer. These are connected with solder bridges between rows of a dual pin-header. [James] removed the bridges and added said pin header. This allows him to jumper the connections and use it as normal, or attach it to his CooCox programmer as seen above. The second part of the project walks through the process of getting the free CoIDE (also based on Eclipse) to compile and program code for the LPCXpresso.
We’ve seen this dev board here and there, notably in an oscilloscope build.
[Roteno’s] submission for the 555 timer design contest is an Internet connected earthquake alert system. It monitors the USGS website for earthquake data and plays a tune when an earthquake occurs. The data is available as a feed in the form of a TXT file which is pretty easy to parse using cURL. He chose an LPCXpresso board (which is an ARM development platform that can run a Linux kernel) along with an XPORT module to handle the Ethernet traffic.
So where does the 555 timer see some action? It is responsible for playing the tone when an earthquake is detected. But playing just one pitch isn’t much fun. Instead, [Roteno] built the circuit above which creates a resistor network switched by a series of transistors. This way he can use GPIO from the microcontroller to choose different pitches. Check out the video after the break to hear the results. At power-up all eight pitches are played as a test, and the alert sound varies in pitch and tempo based on the magnitude of the earthquake.
Continue reading “Earthquake alert system”