Does anybody know why they put 10k resistors between Port B-terminal and socket for the AVR (but just on PB5, PB6 and PB7)? I had to jump them for my application.
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Probably because the In-System Programmming adapter connect to these pins. It makes sure the In-System Programmer can drive these inputs without causing a contention with other signals driven by external devices connected to the board through the socket.
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Yes, these ports are used for programming the device (MOSI, MISO and SCK) of the device. They separate the MCU and the STK(2|3)00 dongle in a very simple fashion.
If you need the pins without resistors for your application, you can use a multiplexer to switch the MCU pins PB5..7 to either the ISP interface OR your application.
It is explained in depth in the STK(2|3)00 manuals or I can send you my own idea of how to work with the multiplaxer IC.
See www.avr-forum.com for schematics of the STK(2|3)00. They show exactly the 2 possibilities!
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