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newguy
Joined: 24 Jun 2004
Posts: 1903
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 Posted: Fri Jul 29, 2005 4:42 pm |
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Uh, the mystery deepens. I'm still using the 18LF458's, not the 4580's. ???
Nope, just found it: they did the same thing in the can-18xxx8.h file. I changed that line to define CAN_ENABLE_DRIVE_HIGH to 1. Now everything works without the external pullups.
PCM, again, thanks. I owe you many beers. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Jul 29, 2005 5:00 pm |
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Oops.
The 18F458 does have that bit. I didn't see it on a quick look at the
data sheet. Also, the can-18xxx8 driver sets ENDRHI = 0 as well.
So how does it work on my boards ? I'll have to investigate this further.
----
OK. Mystery solved. The CAN bus transceiver chips that I've used
in the past have got an internal pull-up on the TX pin.
From page 5 of the MCP2551 data sheet:
| Quote: | | TXD has an internal pull-up resistor (nominal 25 k) |
The LT1796 transceivers don't have an internal pull-up. The data
sheet doesn't show it. That finally explains everything. |
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hoanf
Joined: 27 Aug 2006
Posts: 1
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| Posted: Fri Sep 21, 2007 10:00 pm |
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Thank for your code!
But now how we can use the filter to get the message by using CAN driver . Please give the guide
Cheers
Tran Hoan |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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dan taulbee
Guest
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| CAN troubles |
| Posted: Wed Mar 26, 2008 11:43 am |
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My situation is this:
I'm using a PIC18F4680, and I'm running ex_can.c with the 18xxx8.c and .h files. I do NOT have a CAN developer kit with an LCD display, so I'm pretty sure the printf statements are useless for me. I'm using a program called PCAN-View that monitors the CAN bus. Shouldn't I be receiving the messages from the CANH and CANL pins? The software works when hooked up to a vehicle's CAN bus, but isn't picking anything up from the CAN-EX file.
Dan |
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dan taulbee
Guest
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| resolved |
| Posted: Thu Mar 27, 2008 7:24 am |
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| Ok, now I'm getting CAN data on the CANH and CANL pins of my board. I am not, however, receiving this data on my computer's software. The software (and adapter) once again is PCAN-USB. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Mar 27, 2008 11:04 am |
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| Quote: | | I do NOT have a CAN developer kit |
What board do you have ? |
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