Serial Programmer for AVR microprocessors

  
Atmel described a simple programmer based on the AT90S1200 (NOT the AT90S1200A) controller in their application note, AVR910 (a modification to use the AT90S2313 is also given below).The circuit is so small and simple, I was able to put two of them together without using a printed circuit board, taking only about an hour to assemble each one. Both worked fine without any hitches. These programmers are compatible with RS-232 ports, cost well under US$10 to build, and program AVR chips in the serial mode (and thus is not able to access programming options only available in parallel mode -read those data sheets!). It connects to a target controller via a 6 pin cable.
Serial Programmer for AVR microprocessors - schematic

The target controller needs to have its own clock and power supply. The target also supplies power to the programmer. The 6 pin cable as well as the rest of the system is clearly explained in the AVR910 application note. The programmer works seamlessly with the programmer application that comes with the AVR Studio package and also seamlessly with MacAVRpa, an assembler/programmer application for the Macintosh. The design is clever and works very well. It is an amazing demonstration of what can be done in 1K or ROM and only a 3 level deep stack. Take note that R101 does not do anything important and can be omitted. Though I have not surveyed all of the AVR devices, R103 and R106 are superfluous at least for the AT90S1200 and AT90S2313 and may be omitted. In one unit I used 39k resistors for R105, R102, and R104 to save power and they worked fine (I used a 2N2907 for Q100 and a 2N2222 for Q101).The programmer in the image on this page differs from that described in the Atmel application note in that there is an LED and series resistor connected across the power supply to indicate the presence of voltage, and an LED with series resistor connected from the +5V to the ATS90S1200 pin 16 (reset output) to indicate programmer activity. Sometimes the AVR Programming application from Atmel gets out of sync with the programmer (this does not happen with MacAVRpa ). The LED on the reset line show right away whether the hardware is...



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