I got into AVR chips because they are easy to program, and that has become more and more true over the years with the ever-falling cost of programmers. But it’s pretty easy to make a mistake when burning the fuses on the chips and if you don’t have a proper programmer (my first programmer was a horrifyingly slow self-built DAPA cable) you’ll have a brick on your hands. This little board may be able to help in that situation. I gave the USB µISP a try this week. The half-stick-of-gum-sized board flashes firmware like a champ and includes a rescue pin for when you have clock source problems.
Behold this ATtiny85 based EEPROM programmer. It seems like a roundabout way of doing things, but [Quinn Dunki] wanted to build to her specifications using tools she had on hand. What she came up with is an ATtinyISP USB programmer, pushing data to an ATtiny85, which then programs an EEPROM chip with said data.
The hardware is the next module for her Veronica 6502 computer build. When we last saw that project [Quinn] was planning to add persistent storage for the operating firmware. This will be in the form of an EEPROM programmed with this device. Using ISP and an ATtiny as a go-between means that she should have no problems reflashing the OS without removing the chip. But it all depends on how she designs the interface.
For example, she blew a whole bunch of time troubleshooting the device because garbage data was being written to the chip. In the end, having her manual bus programmer hooked up during the flashing operation was the culprit. Lesson learned, it’s onward and upward with the build.
We’ve been featuring [Quinn’s] projects a lot lately. That’s in part because they’re really interesting, but also because she does such a great job of documenting her experience.