Propeddle, The Software Defined 6502

propeddle

When it comes to building retrocomputers, there are two schools of thought. The first is emulation, that allows for greater compatibility and ease of use, and much easier to find parts. The second requires real, vintage hardware with all the bugs and idiosyncrasies found in vintage chips. Reconciling these two ideas is hard, but the software defined Propeddle manages to do it, all while using a real 6502 CPU.

The trick here is using a Parallax Propeller for the heavy lifting of loading the ROM into RAM with an extremely clever technique using the Reset and NMI pins, generating the clock and other signals required by the 6502, and hosting the keyboard, serial, and video I/O. Already [Jac] has the Propeddle running as an Apple 1 emulator (video below), making it possible to write programs for the Propeddle in BASIC or assembly.

It’s a great design that allows for emulation of a lot of the classic 6502 computers with a real CPU, all while doing away with the cruft of expensive ACIAs and video generation hardware. Awesome work, and we can’t wait for the next version that will be dedicated to [Bill Mensch].

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Magnetic Propeller Balancer Takes Away the Shakes

prop-balancer

[Danijel0frk's] friends may call him unbalanced, but his propellers are always spot on. His well-balanced props are thanks to this magnetic balancer he built from scrap PC parts and pilfered office supplies. Propeller balance has always been important for radio controlled models. Flying for hours with a poorly balanced prop can wreak havoc on an air frame and the radio equipment within.  With today’s drones and R/C vehicles carrying cameras, accelerometers, and gyros, propeller balance has become even more important. A vibrating propeller can ruin a picture at best. At worst it can throw gyroscope and accelerometer readings off and cause a crash.

[Danijel0frk's] balancer is based upon several commercial designs. A steel shaft from a CD-ROM drive is cut and the ends ground to points. A propeller to be balanced is mounted to the shaft. Propellers don’t all have the same hole size so two pen tips are pressed into service as self centering mounts. [Danijel0frk's] picture shows one tip pointing toward the prop hub while the other points away. The balancer will work better if both tips point inward, ensuring the shaft sits directly in the center of the propeller hub’s hole. Hard drive magnets suspend the prop and shaft from a drive rail and wood frame.  We should note that this type of balancer will only perform a static balance. Dynamic balance would require the propeller to be spinning on a motor with force sensors on the shaft. To perform a static balance, material is added to or removed from the propeller until it balances in any orientation. Click past the break for a good tutorial video on balancing.

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JTAGulator Finds Debug Interfaces

jtagulator

[Joe Grand] has come up with a tool which we think will be useful to anyone trying to hack a physical device: The JTAGulator. We touched on the JTAGulator briefly during our DEF CON coverage, but it really deserves a more in-depth feature. The JTAGulator is a way to discover On Chip Debug (OCD) interfaces on unfamiliar hardware.

Open any cell phone, router, or just about any moderately complex device today, and you’ll find test points. Quite often at least a few of these test points are the common JTAG / IEEE 1149.1 interface.

JTAG interfaces have 5 basic pins: TDI (Test Data In), TDO (Test Data Out), TCK (Test Clock), and TMS (Test Mode Select), /TRST (Test Reset) (optional).

If you’re looking at a PCB with many test points, which ones are the JTAG pins? Also which test points are which signals? Sometimes the PCB manufacturer will give clues on the silk screen. Other times you’re on your own. [Joe] designed the JTAGulator to help find these pins.

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Turning anyone into a casuality

Triage

EMTs and other first responders don’t just sit around waiting for a disaster to happen. If they need to train for a disaster – environmental, terrorist, or otherwise – they put together a mass injury simulation, or their version of a war game. As you can imagine, coordinating one of these simulations is a nightmare, but [David] came up with a way to simulate a casualty with a few XBees, a Parallax Propeller, and a few RFID cards.

This triage training simulator consists of an ‘acting coach’ on each simulated victim that includes a speech-to-text module that speaks instructions into the actors ear, a pulse simulator and a readout for vital signs that correspond to twelve major injuries. When an EMT triages a victim, they swipe an RFID card for each medical procedure they perform – intubating is one card, while a bandage is another – and all this is sent back to the coordinator’s tablet.

The coordinator has direct control over each of the actors through a two-way radio link, and can initiate changes in each victim, monitor a paramedic’s responses, and “escalate” the situation by setting off another simulated bomb.

All this is created with off-the-shelf hardware, vastly reducing the cost of this type of training device. An amazing application of what we usually consider to be just robot parts, and we’re happy for [David] to share it with us.

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Pill dispenser tattles to the Internet when you don’t take your pills

pill-taking-reminder-hardware

Here’s another entry in the Parallax microMedic 2013 contest. [Tim] calls it his Propeller-based Internet Logging Pill Dispenser (PDF file), or P.I.L. Box for short.

The hardware is a base unit into which a normal plastic pill organizer is placed. We like this design, as many pharmacies will fill pill boxes for you and this doesn’t complicate that process. You simply pull out the correct box at the beginning of the week and put it in the base unit. You can see one white LED is shining on the Monday slot in the box. This lights up starting an hour before the set pill taking time. This way if you walk by it reminds you. There is also a voice tailor made to scare the elderly that comes out of the speaker, and a simple messages spelled out on the set of seven segment displays. The base unit detects when you press the button to open the pill box and counts that as a properly administered dosage.

Now, if you forget to take the pill it’s not a good thing. The server, which is running on the laptop, will rat you out. It uses the Twitter API to alert whomever is following it — meant for a relative or caregiver — that a dosage was missed. Let’s hope they’re good at keeping up with their Twitter feed!

We remember seeing one other microMedic entry so far, this heart-shaped heart simulator. But we’re going to look around and see how many other good ones we’ve missed.

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Rekindling Forth with a Propeller Jupiter Ace

Jupiter

The Jupiter Ace was a small membrane keyboard, cassette tape drive computer akin to the ZX Spectrum released in 1982. Priced at £90, it was a little more expensive than its home computer contemporaries, but had a very interesting feature: instead of BASIC, the Ace ran Forth. This interpreted stack-based language is far more capable than the BASIC variants found on home computers of the day, but unfortunately the Ace failed simply because Forth was so foreign to most consumers.

Not wanting to let a good idea die, [prof_braino] is bringing Forth back into the modern age. He’s using a Parallax Propeller to emulate a simple home computer running Forth. Instead of a book-sized computer, the new Propeller version runs on a single chip, with 8 CPU cores running 24 times faster than the original, with 32 times more RAM and an SD card for basically unlimited storage.

Heart-shaped heart simulator

Heart

A few years ago, [Addie] over at Tymkrs put together a spooky little Halloween project: a small Propeller board that emulates the electrical signals in a heart. As a cardiac nurse, she thought her project could use a little improvement, and after two years she’s finally done. It’s a heart-shaped board that simulates electrical signals moving through the heart.

There are several key areas that conduct electrical signals through the heart – the sinoatrial node, atrioventricular node, and bundle branches all work like players in an orchestra to keep a heart beating like it should. If something goes wrong with one of these, the heart goes into tachycardia or fibrillation – not good, by any measure. [Addie]‘s board simulates all the different ways a heart can go wrong with LEDs standing in for the electrical signals in a real heart. The name of the game here is to look at the LEDs and tell what state the heart is in.

The PCB heart is just one part of [Addie]‘s heart simulator. The simulated heart can also plug into a neat little heart-shaped project box wired up with a solenoid, LCD display, headphone jack, and other electronics to turn this electronic heart into a complete study tool for heart rhythms. The nurses in [Addie]‘s unit love the thing, and it looks like [Addie] might have a real cardiac training tool on here hands here.

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