2008-07-01 03:05:38     CAN driver of blackfin uclinux in bf537 stamp

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2008-07-01 03:05:38     CAN driver of blackfin uclinux in bf537 stamp

DAVID ZHOU (CHINA)

Message: 58147   

 

Hi all,

 

Recenty, I have been reading can4linux driver of blackfin: there is one thing I can not understand.

 

In data sheet:  page 9-9

 

The CAN controller does not have a dedicated clock. Instead, the CAN

clock is derived from the system clock (SCLK) based on a configurable

number of time quanta.

 

but In can4linux Makefile:

 

ifeq "$(TARGET)" "AD_BLACKFIN"

# integrated CAN of the Analog Devices BlackFin DSP

DEFS =  -D$(TARGET) -D$(DEBUG) -DCAN_MAJOR=$(CAN_MAJOR) \

-DCAN_SYSCLK=125 \

-DMAX_CHANNELS=1 \

#-DCONFIG_TIME_MEASURE=1

 

TARGET_MATCHED = true

endif

 

Why define CAN_SYSCLK=125 ?

 

It is means 125M? but My system clock is 100M , how should I do if I want to make CAN bus

 

woking correctly in 100MHz system clock?

 

Also another question: Can  CANBUS work  in 30K bps ? I find the documents says that it just support bitrate higher than 100 bit.

 

 

 

 

 

 

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2008-07-01 17:27:57     Re: CAN driver of blackfin uclinux in bf537 stamp

Miquel Soler i Mir (SPAIN)

Message: 58168   

 

Hello. If you need more information. Look in forum, there are some posts with more information. (Some from me).

 

CAN_SYSCLK = 125 MHz. If you look in my post, you can find some information about how to ajust the bittiming with diferents Clock System values.

 

CAN at 30 Kbps it's possible but why do you want to have that baudrate ?

 

Miquel Soler i Mir

 

 

 

 

 

 

 

 

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2008-07-01 21:45:30     回复: Re: CAN driver of blackfin uclinux in bf537 stamp

DAVID ZHOU (CHINA)

Message: 58171   

 

Thanks!

 

Because of the network hardware's limit,  most of the time the bit rate is not high.

 

Hi miquelrr,

 

Could show me the easyest way to find these posts?

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