Tuesday, July 29, 2014

Starting work on the ethernet adapter

As I mentioned in an earlier post we have a student working on the ethernet controller for the C65GS using the on-board 10/100mbit ethernet adapter on the Nexys4 board.

We spent a bit of time yesterday understanding how it works, and it is very pleasing that less than 24 hours later I was able to receive this ethernet frame with the C65GS connected by ethernet to my Mac:

 :FFDE800 FF FF FF FF FF FF C8 2A 14 08 DA E2 08 00 45 00 ................
 :FFDE810 01 4E 9C 70 00 00 FF 11 FC DC A9 FE CD 54 A9 FE ................
 :FFDE820 FF FF EB 5D 13 8A 01 3A 33 D6 44 52 49 4E 45 54 ..........DRINET
 :FFDE830 54 4D A9 FE CD 54 C0 0E 00 00 00 3E 39 63 30 31 TM..............
 :FFDE840 61 38 63 30 2D 31 36 37 36 30 39 38 38 39 31 00 ................
 :FFDE850 00 00 00 00 00 00 00 00 00 00 00 00 69 71 6E 2E ............iqn.
 :FFDE860 31 39 39 35 2D 31 32 2E 63 6F 6D 2E 61 74 74 6F 1995.12.com.atto
 :FFDE870 74 65 63 68 3A 78 74 65 6E 64 73 61 6E 3A 73 65 tech:xtendsan:se
 :FFDE880 72 2E 63 30 32 66 38 72 6D 78 64 68 32 68 0A 00 r.c02f8rmxdh2h..
 :FFDE890 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 

Clearly this is not a very interesting ethernet frame for our purposes, but what is clear is that it is locking onto the frame preamble and receiving the bits and putting them together all correctly.

There is no ethernet checksum being performed yet, and it isn't possible to send frames, either.  These are things I will likely work on when I get a chance.

In the meantime the student, now joined by another student, who will work on writing some test software for the ethernet controller.

Once it is all working, then we will look at adding RR.net emulation registers so that existing software can use the ethernet interface.

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