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ATtiny85 Breakout Board

Now that I have a bootloader for the ATtiny85 it's time to simplify the hardware side of things. To that purpose I've designed a small breakout board that makes it easy to set up projects on a breadboard (there are two versions of it available). The bootloader re-purposes the RESET pin as a serial port so at a bare minimum the breadboard will need to include the circuitry required to split the single pin into Tx and Rx pins for the serial cable. Entering the bootloader requires a single pin to be held low when power is applied so I wanted to make that as simple as possible to do as well. Final…

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Microboot on the ATtiny85

The last post gave an overview of the protocol and tools used with the bootloader I've developed - this post describes the implementation details for the version I have running on the ATtiny85. All the code is available on GitHub and released under a Creative Commons Attribution-ShareAlike 4.0 International License. Hardware Requirements The bootloader requires two pins, one to determine if the bootloader should enter programming mode and the other to implement serial communications. These pins are only used when the bootloader code is running, the application is still free to use them for wha…

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Microboot - A Simple Bootloader

In my previous post I alluded to some work I was doing on a bootloader for the ATtiny (and other chips). This has been progressing well so it seemed like a good time to start providing more details. This project is still a work in progress so nothing is completely finalised yet but any changes are going to be fairly minimal. Overview This work came out of two sets of requirements that wound up aligning with each other - the first was my desire for a bootloader to ease the development of some more ATtiny based projects, the second was to develop a bootloader for the prototyping boards I've been…

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