AVR HVSP On A Tiny Breadboard

AVR chips are convenient because you can program them in circuit at their operating voltage. That is, unless you screw up the fuse settings and they’ll no longer listen to an In System Programmer. If you find yourself facing this problem, just build this circuit on a breadboard and ‘unbrick’ by holding down the button.

The circuit seen above is a High Voltage Serial Programmer. This is one of two high voltage protocols used by AVR chips; HVSP is for chips that don’t have enough pins to use High Voltage Parallel Programming. This rendition uses a 12V power source, which is the level necessary for the high voltage method. A 7805 linear regulator joins the mix to provide operational voltage, along with one transistor, an ATtiny2313 to control the circuit, a four-digit 7-segment display for feedback, and one button for control.

Watch the video after the break to see an ATtiny13 programmed to disable the reset pin using a breadboarded programmer. That chip is then easily rescued, having been automatically recognized by using its device signature.


9 thoughts on “AVR HVSP On A Tiny Breadboard

  1. Looks like a useful device – I’ve never really messed with fuse bits but I have a project or two that need one more I/O pin than the ATtiny13A provides. I should probably get round to making a HV programmer and disable that reset pin…

    Also, I love the music on this video!

  2. I have the distinct feeling this device will be saving my arse one day. Thanks for sharing!

    @Pedro: IME, if you ever end up working with ATmega devices, you’ll almost *have to* change the fuse bits at some point. There are dozens of fuse bit calculators online, in addition to several Atmel design notes available on the subject. I usually turn to AVRFreaks.net for such things. :)

  3. I couldn’t find the four digit seven segment LCD at several sites like Sparkfun, Seeedstudio, Parallax, Adafruit, etc. Like I said before, if people can’t build it then it is just show and tell.

  4. @chuckt the led module can be sourced from ebay, or from futurlec. u may also run it w/o the led module and press and hold the button to reset, w/ no display of fuse value. may be i will try to modify the firmware so it can also work w/ red and green leds (just good / bad fuse indicator).

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