MightyOhm

This all started last year, when I was playing with an ATmega168 microcontroller and did something silly.  I programmed the RSTDISBL fuse bit, which effectively makes it impossible to reflash the chip using an ordinary (serial) programmer.

Instead of giving up and throwing out the “dead” chip,  I decided to try to revive it using an obscure high voltage parallel programming mode that isn’t supported by most AVR programmers.  Armed with my Arduino and the ATmega168 datasheet, I quickly designed and constructed a programmer using parts I already had on my workbench.

A few hours later, I tested my new programmer and it worked!  I revived my “dead” AVR by using spare parts and a few lines of Arduino code.  That week I published the schematics and Arduino sketch to the site and called it my Arduino-based AVR High Voltage Programmer.

The response was overwhelming.  Since I first posted the design, many people have built their own and used it to fix their “dead” AVR microcontrollers by restoring the fuse bits to sane values.  I even received several requests for a PCB and/or kit based on the design, which got me thinking…

Today I’m proud to introduce:

The AVR HV Rescue Shield

The AVR HV Rescue Shield is a high voltage parallel mode fuse programmer for Atmel AVR microcontrollers.

It currently supports the ATmega48/88/168/328 series and the ATtiny2313.  The Rescue Shield does everything my original AVR High Voltage Programmer does, and a lot more.  I think the new features make this a really useful tool for anyone working with AVR microcontrollers.

New features include:

• Custom 2-layer PCB with silkscreen and soldermask.  No more hacking and modifying perfboards to fit Arduino’s nonstandard pin spacing!
• Onboard 12V DC-DC boost converter eliminates the need for an external 12V power supply
• Support for two of the most common families of AVR microcontrollers, the ATmega48/88/168 and ATtiny2313
• Support for programming the extended fuse (EFUSE) byte.
• A new interactive mode, where desired fuses can be entered using the Arduino’s serial port.
• Separate Ready and Burn indicators
• Protection resistors on every single data, control, and supply line to the target AVR, meaning that your Arduino and AVR should survive any mishaps during programming, including inserting the AVR backwards or off by 1 pin.

I spent considerable time testing each new feature and documenting the Arduino sketch.  I hope that you’ll find that the finished product was worth the wait!

Ordering instructions:

To purchase bare PCBs and kits, head over to the AVR HV Rescue Shield product page.

100 wonderful, amazing people have joined the Flickr Printed Circuit Boards Group since I launched it in July of last year!

The pool features over 400 pictures of printed circuit boards, many of them CC licensed.  There’s a little bit of everything, from homebrew board fab to PCB jewelry and even miniatature cityscapes.

If you have some cool PCB images of your own, add them to the pool!

One of my favorites: Car Park or Printed Circuit Board?

Big news – the AVR HV Rescue Shield PCBs arrived yesterday!  I’m currently testing them and will post information about kits for sale as soon as I verify that everything is working properly.

This is actually the second spin of the PCB but the first to bear the ‘Rescue Shield’ name.  The first spin was a one-off prototype to check a couple things out, mostly related to the 5V to 12V step up converter.  That design allowed me to fix a couple bugs before doing a production run with the improved design, show below.

So far all I can say is that the step up converter works perfectly.  (Yipee!)

More details to come!

Here’s a really cool Instructable about using a flexible copper-clad material called Pyralux to make flexible printed circuit boards.  You could make some really cool business cards with this stuff.

DIY Flexible Printed Circuits

(via makezine)

As I wait for my AVR High Voltage Programmer Shield PCBs to come back from BatchPCB, I’m starting to wonder what prototype PCB services other people are using for their boards.

Ladyada has a PCB Cost Comparison Calculator that shows the significant differences in price between various low volume PCB vendors, but what’s missing from the chart is the answer to: What vendors are people actually using?

If the cheapest fab house is also the best, obviously the more expensive vendors wouldn’t be around, would they?  Unfortunately, it’s usually not that simple, cheap usually means slow, or low quality, or both.

I know that some visitors to this site make prototype PCBs at home and others send them out to be fabricated.  How do you get your prototype boards made?  Vote below.

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