Category Archives: Microcontrollers

HV Rescue Shield 2.1 Now Shipping

HV Rescue Shield 2.1

I have good news.  The latest and greatest version of the HV Rescue Shield is now available!

Version 2.1 contains a new and improved 12V switching circuit that resolves an issue reading/writing to parts with certain startup timer settings.  This issue affects all previous versions of the Rescue Shield kit.

I have kits in stock and ready to ship this week.  If you have been waiting for the new release, you can place an order now.

Note to HV Rescue Shield 2.0 customers: Because the startup timer issue was identified so quickly after version 2.0 was released, I am offering a free upgrade for all customers who purchased a version 2.0 kit.  Please contact me to arrange for a replacement.  This offer only applies to HV Rescue Shield 2.0 customers.

HV Rescue Shield Update #3

A quick update on the HV Rescue Shield:

About a week ago, I completed testing on a new switching circuit that allows me to leave the DC-DC converter on full-time and switch the RESET signal very quickly (risetimes in the microseconds).   Now there shouldn’t be any more  issues getting parts with zero SUT to enter HVSP/HVPP mode.

It’s taken a lot longer than I expected to get to this point, but the results look very good. I have had 100% success reading/writing all parts I have tested.

PCBs are on order and due to ship by the end of the week.  Assuming the layout is good and I didn’t just order a large batch of stylish (but small) coasters, I should have kits in stock again by the end of next week.

Watch here for updates, and my apologies to everyone who has been waiting on a kit – new and improved kits should be available soon.

Update 2/1: PCBs came in while I was away last week, and are currently being held at my local Fedex office, which is closed due to the power outages that are affecting Austin today.  Apparently Austin does not handle prolonged sub-freezing temperatures very well.   As soon as I can get my hands on the boards, it should only be a day or two before kits are available again.

HV Rescue Shield 2.0 status update

Just before the holidays, an issue with the Rescue Shield 2.0 (which I have at times referred to as “2.x”) was identified.  The issue involves problems reading/writing to parts that have certain startup timer (SUT) fuse values set.

There is some more information about the issue on the forums and in a previous post here and I created a Known Issues page on the wiki.

While this issue will not affect most users (this is why no one, including me, noticed it until now), I am currently working on a fix.  Initially I had hoped that I could fix the problem in software, but after spending far too much time pursuing that approach, I have decided to address it with a hardware change instead.  This should make for a much more robust solution.  I’m in the process of revising the hardware this week and hope to release a new version of the shield in the near future.

As soon as I heard about the issue in December, I stopped taking orders for Rescue Shield kits.  Kits and PCBs will show up as out of stock until I release the new version.

I’ll post another update when I have an estimate of when kits will be available again.

Thanks for your patience!

Issue with Rescue Shield and targets with SUT = 0ms

HV Rescue Shield 2.0 customer Matthew Beckler has uncovered an issue that affects all variants of the Rescue Shield.

Long story short, if the target AVR is configured for a fast internal clock and zero startup time (eg. LFUSE=0x62 on the ATtiny13A gives a 9.6MHz clock with 14CK +0ms startup delay), then a slow rising edge on the 12V RESET signal from the Shield results in the target not entering or dropping out of HVSP or HVPP mode.  The symptom is that regardless of the fuses stored on the target, the Rescue Shield fuse reads return 0xFF.  In addition, the fuses can’t be changed.

I am currently investigating a solution.  There is more information about the issue and updates regarding debugging in the HV Rescue Shield support forum.

New Product: HV Rescue Shield 2.0

HV Rescue Shield 2.x

The HV Rescue Shield 2.0 is a high voltage parallel mode fuse programmer for Atmel AVR microcontrollers.

It currently supports a wide variety of AVR chips, including the 28-pin ATmega48/88/168/328 series, the 20-pin ATtiny2313, and many 8-pin ATtiny devices (such as the ATtiny25/45/85 and ATtiny13A).  A list of supported devices is in progress, but the Rescue Shield supports many more devices than those listed on the wiki.

The HV Rescue Shield 2.0 is in stock and ready to ship today!  Scroll down to place an order.

New in release 2.0:

  • Support for 8-pin ATtiny devices that use High Voltage Serial Programming (HVSP) mode!
  • Mode selection at startup so you don’t have to recompile the Arduino sketch to change parts.
  • More reliable HFUSE burning on all HVPP targets.
  • Numerous minor bug fixes and speed improvements to the code.
  • Reduced price, kit is now only $19.95 (was $24.95).   This means the kit is lower cost, but with more supported parts!


  • A working Arduino (tested with Arduino Uno, Duemilanove and Arduino NG)
  • A computer with USB and the Arduino IDE installed (tested with Arduino 0021)
  • A soldering iron and basic electronics assembly skills

What you get:

  • A high quality printed circuit board with the DC-DC converter preassembled, as shown below.
  • All other components needed to build the kit
  • An Arduino sketch, assembly instructions, Eagle schematics and layout files.

Here is a snapshot of the components included with the kit.


How to Order:

Visit the HV Rescue Shield 2.x product page to place an order.