I've just been scanning the XS1-L and XS1-G documents with a view to understanding how to connect external links to other CPUs or FPGA etc. In particular I'm interested in getting the two wire links working at 5Mb/s and possibly 10Mb/s.
I have some concerns here:
Firstly the L and G links don't seem to be compatible with each other after. Apart from speed issues one has a HELLO token in its protocol the other does not. Is it possible to connect L and G devices together via their links?
From the XS1-L spec I see that the 2 wire link data rate is 160/S Mb/s where S is the switch clock speed. So 5Mb/s is easily achievable by slowing the switch clock. Alternatively the bit and token spacing can be stretched at the same switch clock speed to get down to 5Mb/s.
For the XS1-G devices the sec has a different statement of link speed. Where data rate is 320/x Mb/s where x is the bit spacing. There is no mention of switch speed. Is this correct? It seems impossible to get down to 5Mb/s by setting the bit spacing because the register for clocks between bits is only 4 bits wide. Is it possible to get a G device link down to 5Mb/s ?
In the tools manual I see how to configure the inter bit and inter token delays in xn files. Is it also possible to configure the switch clock from there?