I am new to the SPI-on-atmega (have been using USI on tiny's before). I have a very simple question, with probably a less simple answer (can't find it...)
I am debugging a SPI problem and it strikes me that MOSI is idle HIGH. I have no pull up resistors on the MOSI line, only a 33k resistor to a transistor to a led (for monitoring, just like some other outputs).
The led goes on as soon as I enable SPE in SPCR, iow as soon as SPI is enabled. I am quite aware that I loose the normal output function of the port, but I don't expect it to be idle HIGH.
I am also aware that the state of the MOSI line is only really valid during clock transition.
I already did a loop-back test (mosi to miso) and that seems to work though.
Still it's strange. Is this expected behaviour?