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Radical AVR USB programmer design

You’ve probably seen many AVR ISP programmers that come with USB connection. Some of them use software based USB stack emulation, others use hardware USB or specialized chip like FTDI USB to serial. Anyway all of these are at some level quite complex and most of them require to be somehow programmed in order to operate. Well this one is different as it uses an USB hub for USB interface. So this programmer doesn’t use any other USB chips but hub itself. The idea is brilliant: it uses four hub ports that can be enabled and disabled from PC software this way creating pulses on each hub output. Sending these pulses through simple logic Quad 2-input NAND gate you get all signals required to program AVR chip via ISP interface. Currently software works only with Linux, but who knows – the idea itself is great to move towards cheap and simple USB ISP programmer. Continue reading