On 08/14/2010 07:44 PM, Marc Kleine-Budde wrote: > Wolfgang Grandegger wrote: >>>>> I see that you typical use a sample point at 75%. >>>>> CANopen has a "Recommended location of sample point" at 87.5%. (CiA 301). >>>> I don't have access to the standard, but [1] lists a sample point of 75% >>>> for 1000 kbit/s and 80% for 800 kbit/s. All slower bitrates have the >>>> 87.5% sample point. > >>>> [1] www.can-cia.org/fileadmin/cia/files/icc/9/koppe.pdf >>> It's from 2003 >>> I hope the list will accept small pictures. >>> From CiA301 Version 4.1, 11. April 2007 >> >> Grrr, our current settings are based on the following mail: >> >> https://lists.berlios.de/pipermail/socketcan-core/2008-May/001231.html >> >> For backward compatibility, I'm not sure if I want to modify them silently? > > I just checked with the "can-calc-bit-timing". The current algorithm > find the same bit timing parameters for all can cores, no matter if > we're using the older or the newer CIA recommendations.
Hm, but not for 1MHz/sec: $ ./can-calc-bit-timing -b 1000000 sja1000 Bit timing parameters for sja1000 with 8.000000 MHz ref clock nominal real Bitrt nom real SampP Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP Bitrate Error SampP SampP Error BTR0 BTR1 1000000 125 2 3 2 1 1 1000000 0.0% 75.0% 75.0% 0.0% 0x00 0x14 $ ./can-calc-bit-timing -b 1000000 -s 875 sja1000 Bit timing parameters for sja1000 with 8.000000 MHz ref clock nominal real Bitrt nom real SampP Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP Bitrate Error SampP SampP Error BTR0 BTR1 1000000 125 3 3 1 1 1 1000000 0.0% 87.5% 87.5% 0.0% 0x00 0x05 I'm actually thinking to printout some kind of warning if 1 MHz/sec is seleceted, e.g.: dev_warn(dev, "New CIA recommended sample point of 0.875 used"); Wolfgang. _______________________________________________ Socketcan-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/socketcan-users
