Hi,
it took me a while but the first beta is online

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https://github.com/dioannidis/libUSBUARTTerminal USBaspUARTTerminal is a standalone application, that connects to a UART enabled USBasp programmer ( running the usbasp-uart firmware (
https://github.com/akrasuski1/usbasp-uart ) ).
If you play / experiment with standalone ( i.e. breadboard, custom board ... ) avr mcu's you don't need anymore an extra UART->USB converter device.
In my tests, I couldn't get reliable data stream ( loosing a byte here and there ... ) with a baudrate of 57600 and more. But for my use, quick UART debugging, using 38400 baudrate is more than adequate.
I uploaded windows binaries ( and64, i386 ) and made the project able to compile in official Lazarus 2.0.8 ( I'm using fpc and lazarus trunk for development .... ) .
Next steps is to integrate the USBasp library to the LazSerialMonitor package and extend it to program the avr mcu's ( SPI, TPI ) directly

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regards,