On 16.08.2021 16:30:52, Marc Kleine-Budde wrote: > > Finally, I did a bit of research and found that: > > http://ww1.microchip.com/downloads/en/DeviceDoc/Section_56_Controller_Area_Network_with_Flexible_Data_rate_DS60001549A.pdf > > This is *not* the mcp25xxfd datasheet but it is still from > > Microship and as you will see, it is mostly similar to the > > mcp25xxfd except for, you guessed it, the TDCO. > > > > It reads: > > | TDCMOD<1:0>: Transmitter Delay Compensation Mode bits > > | Secondary Sample Point (SSP). > > | 10 = Auto; measure delay and add CFDxDBTCFG.TSEG1; add TDCO > > | 11 = Auto; measure delay and add CFDxDBTCFG.TSEG1; add TDCO > > | 01 = Manual; Do not measure, use TDCV plus TDCO from the register > > | 00 = Disable > > > > | TDCO<6:0>: Transmitter Delay Compensation Offset bits > > | Secondary Sample Point (SSP). Two's complement; offset can be > > positive, zero, or negative. > > | 1111111 = -64 x SYSCLK > > | . > > | . > > | . > > | 0111111 = 63 x SYSCLK > > | . > > | . > > | . > > | 0000000 = 0 x SYSCLK > > > > Here, you can clearly see that the TDCO has the exact same range > > as the one of the mcp25xxfd but the description of TDCMOD > > changes, telling us that: > > > > | SSP = TDCV (measured delay) + CFDxDBTCFG.TSEG1 (sample point) + TDCO > > > > Which means this is a relative TDCO. Good catch! Microchip is investigating this. regards, Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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