In one of the application, there are two micro controllers involved (Mega16 and Tiny44). They communicate with each other through SPI port. So far the devices used were DIP packages and as such they were programmed externally and then inserted in their sockets. Now we want to change the packages to SMD and hence the ISP method is opted for.
Reading the application note AVR910, it says that ISP programmer communicates over SCK, MISO and MOSI. To avoid driver contention, a series resistor should be placed on each of these lines if there is a possibility that external circuitry could be driving these lines.
This certainly is the case in my application. My question is what should be the value of these resistors.