I just want to know what is the optimal SPI buffer size I should use in the AN3906(serial to Ethernet bridge) software.
I have interfaced MC9S12XDP512 to MCF51CN128 through SPI and both are configured to work at max frequency.
The coldfire controller MCF51CN128 is configured as SPI slave.
That's a good question CHary, but unfortunately it's something you'll need to arrive at as it totally depends upon your application and data that you are transcieving. If your application is very responsive to clearing out the buffer and your data is small then you'll get away with a small buffer, and of the course the converse is true. The maximum data size of an IP Datagram is 1500 bytes.
Sounds like an interesting project BTW.