USBASP is well-known USB programmer for Atmel AVR microcontrollers initially supported by Thomas Fischl. USB ASP is made of an Atmega8 and few components. The programmer uses a firmware driver that makes this programmer attractive to many amateurs.
Another thin why this programmer is so popular â€“ because it is officially included and supported in WinAVR (now version 20070122).
Once again let us see what this programmer is made off and how to set it up.
The original circuit you will find in authors site: https://www.fischl.de/usbasp/
The core of the USBASP adapter is Atmega8 microcontroller clocked by the 12MHz crystal. A soldered board is ready to be connected via simple USB cable with B type connector (Computer side needs A type of connector). Resistors R2 and R6 are current limiting resistors that protect the computer USB port. Resistor R7 helps the computer to recognize the device as LS (Low Speed). Diodes D1 and D2 indicate data transfer. Header SV1 is compatible with STK200/300 just 4, and 6 pins are used for RXD and TXD (may be used for other purposes).
SCK signal can work at two frequencies 1.5MHz and 8MHz 375kHz and 8kHz which can be selected by Jumper JP3. If Jumper is unconnected, then SCK speed is 8MHz 375kHz. Low speed SCK is used when MCU is clocked with low speed oscillator like 32kHz.
Jumper JP1 is used for programming adapter itself via ISP adapter. And last Jumper JP2 is used for powering adapter from the USB port (not recommended).
This is how my adapter looks like:
Few words about setting up USBASP adapter for work in Windows XP system.
After the firmware is uploaded, then connect the USB cable to the adapter.
Connect cable directly to USB port of computer avoiding Hubs (in my case computer didn’t detect adapter connected through a hub);
Wait for windows information â€œNew Hardware Found USBASPâ€. If the device isn’t discovered, check the board for errors and reconnect again;
After device is detected Driver setup wizard opens. Select where USBASP driver is located. It is in the directory you’ve downloaded with firmware. If you unpacked in C: drive, then the driver should be in C:\usbasp.2006-12-29\bin\win-driver\ and press next:
After successful setup you should see the following view in device list:
When the device is unplugged â€“ the device disappears from the device list. This is it with the first stage. Now it is time to start programming with usbasp adapter, but this will be discussed later.
You can download various PCB and circuit configurations directly from https://www.fischl.de/usbasp/ site. Good luck.