USB AVR programmer

  
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Nowadays, USB is the most popular connection connection between PC and peripherals such as AVR programmers, printers, scanners etc. For that reason I had to modify my old serial AVR In-System-Programmer (ISP) to work with USB connection. You can say, `use a USB to Serial adaptor to connect your AVR ISP with your PC`. Yes, that could be a solution
USB AVR programmer - schematic

but it would cost me more money than a singe FT232BM chip because I had to include an USB to RS232 adaptor and a power supply for my programmer. (almost 30). So, the solution was to replace the two transistors, that were used to adapt the RS-232 voltage levels to TTL voltage levels, with a USB to RS-232 chip such as FT-232BM. Following the schematic diagramthat I read in the FT232BM manual I made the connections between ATtiny2313 and FT232BM. The FT232BM requires a few and ordinary components to work. When you connect this circuit to your PC you will see the message " a new hardware was found" and then the factory name of FT232BM. IC1 is a serial EEPROM that used to store user`s settings. So, you can rename this programmer to be appeared as "AVR In-System-Programmer" or "MyAVR programmer". Furthermore, you can add the firmware version of your circuit. Of cource, you can bypass this component because it`s optional. I saw that the programmer works with orwithout this EEPROM. Anyway, FTDI suggests you to use this EEPROM. Led D1 flasheswhen data are transmitted or received by FT232BM. CN1 is a USB-B connector and CN2 is a 6-pin connector to your target AVR (it is connected to the AVR to be programmed). The S1 switch is used to supply your target circuit with +5V from the USB connector of your PC. In this case you won`t need any additional power supply for your target circuit. Consider that a single USB port can supply up to...



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