LPC4357 CAN problem

swapnilkulkarni — Tue, 21 Jun 2016 12:54:34 GMT

I have written a driver for LPC4357 CAN. CAN bus was not working when CPU clock is set at 204MHz. Whenever a message is sent, bit 0 error occurred and CAN entered in bus off state.

Then I checked with different CPU clock frequencies.

I could go upto 200MHz when other CAN node is LPC1768.

But when other CAN node is LPC4357, I could go upto 120MHz only.

Is there anything wrong with my CAN driver or there is something to be handled with CPU clock?

As per data sheet, CAN peripheral clock should be less than 50MHz. I have taken care of it by using CAN CLKDIV and IDIVD clock source.

Also I am not using any peripheral on APB3 (I2C, ADC, DAC) as per mentioned in errata.

Re: LPC4357 CAN problem

kerryzhou — Thu, 28 Jul 2016 07:26:10 GMT

Hi Swapnil,

You said:

I could go upto 200MHz when other CAN node is LPC1768.

But when other CAN node is LPC4357, I could go upto 120MHz only.

It seems, still relate to your other CAN node, did you try to use the CAN Tool as the CAN node and try again?

Besides, when you used difference other CAN node, choose different base clock, eg, 204MHZ, 120Mhz, lower than 100Mhz, try to configure as the same CAN baud, then test the CAN_TX pin, check the wave, any difference on your side?

Another way for your reference, you also can test our lpcopen CAN driver, when you choose higher base clock for CAN module, whether it will meet the same question.

The lpcopen CAN driver can be downloaded from this link:

LPCOpen Software for LPC43XX|NXP

Folder path: lpcopen_2_12_keil_iar_keil_mcb_4357\applications\lpc18xx_43xx\iar_ewarm_projects\keil_mcb_4357\periph\periph_ccan

Please test it again, if still not OK, please give me your test wave in the CAN_TX pin with different base clock and the same CAN baudrate.

Have a great day,
Jingjing

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