VERY useful answer - thanks.
Is this right though?
"Let's assume SPE = 2 and MSTR = 4 (they probably aren't but I couldn't be bothered looking them up)
(1<<SPE)|(1<<MSTR) == (1<<1)|(1<<4) == 00000010 | 00010000 == 000100010 == 0x12"
Should it be this? :
(1<<SPE)|(1<<MSTR) == (1<<2)|(1<<4) == 00000100 | 00001000 == 00001100 == 0x12"
In the end, do I want to set SPCR as I have, then set the SPSR right after?
// SPCR = 01010000
//interrupt disabled,spi enabled,msb 1st,master,clk low when idle,
//sample on leading edge of clk,system clock/4 (fastest)
SPCR = (1<<SPE)|(1<<MSTR);
SPSR = (1 << SPI2X); //toggle this 0 to a 1 in order to switch on "SPI2X" register value
clr=SPSR;
clr=SPDR;
ALSO, as an example, if I wanted to slow things down I would set that rightmost SPRO bit on, by basically making that 0 a 1 like so:
SPCR = (1<<SPE)|(1<<MSTR) |(1<< SPRO);
Thanks!