Poor mans AVR programmer from USB keyboard

In order to program AVR microcontrollers using ISP interface only four control signals are required – SCK, MISO, MOSI and RESET. Steve figured out that these signal could be controlled using USB keyboard three LED indicators and keyboard key. LEDs can be easily toggled using HID device specification. So these signals come from PC as MOSI, SCK and RESET. MISO was received from device as keyboard key presses. A little trick had to be done with optocoupler in order to achieve this. He wrote an avrdude interface driver for this programmer, so its pretty easy to use. Problem is that programming speed is slowish because of attempt to debounce MISO line. Anyway, this is great hack that might be useful for someone. Continue reading

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

AVR USBtinyISP programmer and SPI interface

Seems like everyone is shifting their own ISP programmers from COM and LPT ports to USB. And there is a reason for this – computers arre getting mobile, LPT and COM ports becoming obsolete. But almost everywhere you can find USB port, so it is logical to have USB programmer rather then old style. ladyada have developed very tiny USB ISP programmer which also can serve as USB-SPI interface. Thisis really low cost and low component count programmer built under Attiny2313 AVR microcontroller. It is compatible with AVRDUDE and AVRStudio and works under Windows, Linux and MacOS.   This is not the fastest programmer but it can guarantee write speed of1 Kb/s and read speed of 2Kb/s. Other good feature is that it comes with both – 6 and 10 ISP connector types. You can build this adapter easily as all necessary files are available for download, or you can simply order a kit. Continue reading