-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Marc Kleine-Budde wrote: > the "funny" thing is the currently used algorithm provides better values > with a tseg_min of 4 the with 2. The bitrate errors percentage is > comparable low, but the sample point error is bigger. > > Probably due to this: > If you have lesser number of entities (I means this blocks with the > length of a time quanta), you loose time resolution to position your > sample point. > >> [frog...@hardanger:berlios-can-utils (test)]$ ./can-calc-bit-timing flexcan > > tseg1_min == 4, 49.875000 MHz ref clock
Doh1, that's tseg1_min == 2 > >> Bit timing parameters for flexcan with 49.875000 MHz ref clock >> nominal real Bitrt nom real SampP >> Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP Bitrate Error SampP SampP Error >> CAN_CTRL >> 1000000 200 1 1 2 1 10 997500 0.2% 75.0% 60.0% 20.0% >> 0x09010000 >> 800000 180 2 2 2 1 9 791666 1.0% 80.0% 71.4% 10.8% >> 0x08090001 >> 500000 401 1 1 2 1 20 498750 0.2% 87.5% 60.0% 31.4% >> 0x13010000 >> 250000 802 1 1 2 1 40 249375 0.2% 87.5% 60.0% 31.4% >> 0x27010000 >> 125000 421 7 8 3 1 21 125000 0.0% 87.5% 84.2% 3.8% >> 0x143a0006 >> 100000 1664 1 2 2 1 83 100150 0.1% 87.5% 66.6% 23.9% >> 0x52090000 >> 50000 3328 1 2 2 1 166 50075 0.1% 87.5% 66.6% 23.9% >> 0xa5090000 >> 20000 3568 5 6 2 1 178 20014 0.1% 87.5% 85.7% 2.1% >> 0xb1290004 >> 10000 4350 8 8 6 1 217 9992 0.1% 87.5% 73.9% 15.5% >> 0xd83d0007 > > > tseg1_min == 2 this is == 4 > >> Bit timing parameters for flexcan with 49.875000 MHz ref clock >> nominal real Bitrt nom real SampP >> Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP Bitrate Error SampP SampP Error >> CAN_CTRL >> 1000000 100 3 3 3 1 5 997500 0.2% 75.0% 70.0% 6.7% >> 0x04120002 >> 800000 180 2 2 2 1 9 791666 1.0% 80.0% 71.4% 10.8% >> 0x08090001 >> 500000 200 3 4 2 1 10 498750 0.2% 87.5% 80.0% 8.6% >> 0x09190002 >> 250000 501 2 3 2 1 25 249375 0.2% 87.5% 75.0% 14.3% >> 0x18110001 >> 125000 421 7 8 3 1 21 125000 0.0% 87.5% 84.2% 3.8% >> 0x143a0006 >> 100000 1002 3 4 2 1 50 99750 0.2% 87.5% 80.0% 8.6% >> 0x31190002 >> 50000 1664 4 5 2 1 83 50075 0.1% 87.5% 83.3% 4.8% >> 0x52210003 >> 20000 3568 5 6 2 1 178 20014 0.1% 87.5% 85.7% 2.1% >> 0xb1290004 >> 10000 4350 8 8 6 1 217 9992 0.1% 87.5% 73.9% 15.5% >> 0xd83d0007 > > > tseg1_min == 4, 66.500000 MHz ref clock == 2 > >> Bit timing parameters for flexcan with 66.500000 MHz ref clock >> nominal real Bitrt nom real SampP >> Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP Bitrate Error SampP SampP Error >> CAN_CTRL >> 1000000 165 1 2 2 1 11 1007575 0.8% 75.0% 66.6% 11.2% >> 0x0a090000 >> 800000 210 1 2 2 1 14 791666 1.0% 80.0% 66.6% 16.8% >> 0x0d090000 >> 500000 105 7 8 3 1 7 500000 0.0% 87.5% 84.2% 3.8% >> 0x063a0006 >> 250000 285 5 6 2 1 19 250000 0.0% 87.5% 85.7% 2.1% >> 0x12290004 >> 125000 571 5 6 2 1 38 125000 0.0% 87.5% 85.7% 2.1% >> 0x25290004 >> 100000 526 7 8 3 1 35 100000 0.0% 87.5% 84.2% 3.8% >> 0x223a0006 >> 50000 1428 5 6 2 1 95 50000 0.0% 87.5% 85.7% 2.1% >> 0x5e290004 >> 20000 2631 7 8 3 1 175 20000 0.0% 87.5% 84.2% 3.8% >> 0xae3a0006 >> 10000 ***bitrate not possible*** > > > tseg1_min == 2 == 4 >> Bit timing parameters for flexcan with 66.500000 MHz ref clock >> nominal real Bitrt nom real SampP >> Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP Bitrate Error SampP SampP Error >> CAN_CTRL >> 1000000 90 3 4 3 1 6 1007575 0.8% 75.0% 72.7% 3.1% >> 0x051a0002 >> 800000 180 2 2 2 1 12 791666 1.0% 80.0% 71.4% 10.8% >> 0x0b090001 >> 500000 105 7 8 3 1 7 500000 0.0% 87.5% 84.2% 3.8% >> 0x063a0006 >> 250000 285 5 6 2 1 19 250000 0.0% 87.5% 85.7% 2.1% >> 0x12290004 >> 125000 571 5 6 2 1 38 125000 0.0% 87.5% 85.7% 2.1% >> 0x25290004 >> 100000 526 7 8 3 1 35 100000 0.0% 87.5% 84.2% 3.8% >> 0x223a0006 >> 50000 1428 5 6 2 1 95 50000 0.0% 87.5% 85.7% 2.1% >> 0x5e290004 >> 20000 2631 7 8 3 1 175 20000 0.0% 87.5% 84.2% 3.8% >> 0xae3a0006 >> 10000 ***bitrate not possible*** Marc - -- Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de | -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkwaOxMACgkQjTAFq1RaXHMvbgCcC3Vdy0VGP1u3yc03Q5QoWqTQ Wd0An3SZcghyIig70xTCLPZOO5+87HBj =xOop -----END PGP SIGNATURE----- _______________________________________________ Socketcan-core mailing list [email protected] https://lists.berlios.de/mailman/listinfo/socketcan-core
