[Scott Harden] has already produced some projects which measure analog inputs. But he’s got plans for more and wanted a base system for graphing analog signals. You can see the small board next to his laptop which offers the ability to sample up to six signals and push them to a PC via USB.
The ATmega48 and a few supporting components are all you’ll find on that board. The USB connection is taken care of by an FTDI cable. He went that route because the cables are relatively cheap, easy to come by, and already have driver support on all the major operating systems. If you look at the screen you can see a window graphing one analog input in real-time. He wrote this in Python (which is once again a cross-platform tool) and it has no problem graphing all six inputs at once.
This is immediately useful as an upgrade to [Scott’s] ECG machine. His future plans include a Pulse Oximeter, EEG, and EEG.
Sometimes, expensive calculators hit the floor. It’s happened to almost anyone with a graphing calculator from TI or HP. Sadly, they don’t always bounce. After this happened to [Howard C.], an Industrial Engineering student from U. of Iowa, he decided to spend $50 on milling his own replacement case out of aluminum rather than trashing the device over a broken battery compartment. [Howard] chose to send us the story rather than write his own blog, so we’ve included all the great pictures he sent us after the break.
Continue reading “Indestructible TI-89″
It looks like we missed the boat on this one but just in case you missed it everywhere else on the Internet, last Saturday [Matt Stack] introduced the world to a completely open source calculator. This marries two heartily tested open source projects; the R Project for Statistical Computing and the Beagleboard. The hardware side of things is very similar to that Linux tablet from back in June. It uses a stock Beagleboard with the BeagleTouch module.
Why do we care? First off, don’t forget what’s under the hood. That ARM processor kicks the 6 MHz Z80 processor found in TI’s calculators to the curb. The R language is a boon as well, offering plots of almost limitless quality and allowing extensibility that can’t be equaled with the current non-open offerings. But mostly because it’s a hack. We like seeing software run on hardware it wasn’t intended for.
[Michael Vincent] turned his TI-84 Plus into a spectrum analyzer. By running some assembly code on the device the link port can be used as an I2C bus (something we’ll have to keep in mind). After being inspired by the cell phone spectrum analyzer he set out to build a module compatible with the calculator by using an I2C port expander to interface with a radio receiver module. Now he can sniff out signals between 2.400 and 2.495 GHz and display the finds like in the image above.