I'm using the LPC2378 (MCB2300) with an external serial flash ( M25P80). I use the SSP port to have the fastest SPI clock (18MHz).
I succeed in using SSP0 clock at 18MHz but my issue is that my interrupt is too long (i build my own routine interrupt from an internet code). Thus, using a clock of 4.5MHz give me the same writing or reading timings than using a 18MHz clock. That is to say that my interrupt takes 1.4us to act and 1.1us to start. So in 2.5us I can put 8 clocks at 4.5MHz (8*222ns=1.8us) as well as 8 clocks at 18MHz(8*56ns=444ns).
I'm sure that some people worked at high frequency but did they measure the 'real' writing and reading timings ?
I wonder if someone already used a SSP interrupt faster than 1 us ?
Any help is welcomed. Thanks everybody.