lpcware

LPC11Cxx CAN baud rate calculation?

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by kty-tty on Fri Jan 27 02:57:39 MST 2012
Hi,
I have a 12MHz crystal on an LPC11C12, and I am trying to initialise the C_CAN for 1MHz.
I am having trouble with the bit timing initialisation. I can't find the PROP_SEG value or register!!
As you know the CAN bit timing is broken into 4 segments, and the baud rate is the inverse of the sum of each of them ie f=1/(tsync + tprop+tph1+tph2). Without the prop term how do i work this out?
ie can someone please help me with the BT register settings for 1MHz from a 12MHz crystal?

I have tried to reverse engineer the settings from the sample codes to work out what the PROP_SEG value is if it is fixed but am not having any luck. I am also new to CAN so would like some guidance on positioning of the thp1/tph2.
Any help appreciated.

Also, I have very low power requirements I am trying to meet so cannot just change the PLL for 48MHz. If worst comes to worst I might change it for 16MHz, but i would rather not!

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