I've always used SPI for this sort of thing in the past, but I need something *much* faster.
I need to transfer 4-bit data between two MCUs, in one direction, between a slave and master, as fast as possible (I actually need to transfer 24 bits in total). Both are on the same PCB and share the same clock. Would it be feasible to, say, raise an output on the master when it needs the data, the slave, when it sees the corresponding input go high, will then send six nibbles one after the other and the master will receive them, without any additional handshaking. I can't see any problems with this arrangement, can anyone else?
MCUs are AVR 2313s, BTW.
The actual application is a software DDS running on the master (generating sinusoidal 17 kHz to 25 kHz), which needs updating with frequency data in the main program loop, without generating any glitches in the output. The slave handles the user I/O - two push-buttons (up and down) and an LED.
Thanks for any input.
Leon