Hello, I've problems with receiving packets with an TQM8260 board on the SCC 10Mbit ethernet interface.
If I connect two tqm boards directly via an ethernet crossover cable and send udp packets from one board to another the receiving CPM marks 1-15% of all packets with an crc error flag (this depends on packet size and send speed). When I check the udp checksum of the received packets this check only ails for approx 5-10% of the marked packets, e.g. Send packets in 5s CPM says CRC-Error[1] UDP checksum error ===================================================================== 6000 (512 bytes each) 591 / 9.8% 94 / 1.6% 4850 (512 bytes each ) 220 / 4.5% 34 / 0.7% 6000 (128 bytes each) 182 / 3% 43 / 0.7% The faster the packets are send and the longer the packets are the more errors are detected. If I send the packets with a rate <50 packets/s I got almost no crc errors. I'm very surprised over the errors, as I use a direct connection between the boards and send only in one direction. In such a case I would expect to get no errors. Can this be an EMI error of the physical SCC ethernet interface of the tqm boards? I also connected the tqm board via a switch to a PC 10Mbit ethernet interface and got slightly smaller error rates, but they are still there. If I use the FCC ethernet interface I don't get this problems. Did anyone make similiar experiences or has an idea how this errors can happen? I use the DENX linux-2.4.4-2002-10-06 (patched for RTAI linux 24.1.10) and enabled full duplex mode in the SCC enet.c driver (without full duplex I got also crc errors and lots of dropped packets). Thomas Geffert Footnotes: [1] I got this value from the scc1 parameter ram field crcec. -- Dipl.-Ing. Thomas Geffert KEYMILE / Datentechnik Intercom GmbH Frankenring 14, 30855 Langenhagen, Germany Tel +49 (0)511 978197-669 / Fax +49 (0)511 978197-670 mailto:thomas.geffert at keymile.com / http://www.keymile.com <<< Since 1st of October 2002 Datentechnik & Ascom Transmission serve you as KEYMILE >>> ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
