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TX errors with c_can..

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tjoAG
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Joined: 2012-05-30
Posts: 50

Hi all,

I'm stucked getting the c_can of my lpc1517 todo some actual transmiting..!

HW:
MCU: LPC1517 Default TD and RD on P0.13 and P0.18
TJA1051 transceiver
XTAL is a 12 MHz cheramic one with 0.5% accuracy

SW:
Using the lpcxpresso 1548 ccan_rom sample (changed to the correct MCU type and rebuild) and KEIL MDK
Using default bit rate of 500k in the sample

The hardware department has verified that the TJA1051 is placed and connected correctly.
The c_can register and pin mux register seems to be set up fine.

When I do a simple transmite (just in the sample) i get TX error from the c_can:
STATUS register: 0x000000E5:
BIT0ERROR, During transmission of the message the device wanted to send a low/dominant, but the monitored bus value was high/recessive

I have tried using the TEST mode of the c_can module and forcing the TC high and low using the TEST register. The TX pin P0.18 doesn't toggle. It is always high.
If I move the CAN TD/RD to a diffrent set of GPIO's (With nothing attached), the TD can be toggle using the TEST register. --> The TJA1051 'jam' the TX/RD signals??? But why??

I'm all out of ideas. Any one with any suggestion would be appreciated.

Thomas

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