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csminus
csminus
Associate II
June 15, 2015
Question

Can Bus, sending and receiving does not work

  • June 15, 2015
  • 42 replies
  • 5621 views
Posted on June 15, 2015 at 21:25

ghhhhhhhhhhhhk

#lmgtfy #can-bus #stm32f207 #can-prescale-and-quanta
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Tesla DeLorean
Tesla DeLorean
Guru
June 24, 2015
Posted on June 24, 2015 at 17:37

eh i try almos all prescalers and still nothing, maybe its converter problem but i cant check it i think

 

I've never found banging in random values a good way to diagnose problems.

Do you have a schematic for this board you're using? Please provide.
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csminus
csminusAuthor
Associate II
June 24, 2015
Posted on June 24, 2015 at 18:19

i was count and i set 4 for 500 br, and i set same br on converter. I have schema only on paper but i try make it fast on pc

Tesla DeLorean
Tesla DeLorean
Guru
June 24, 2015
Posted on June 24, 2015 at 18:27

i was count and i set 4 for 500 br, and i set same br on converter.

 

500Kbps

That would be coherent with my understanding that the CAN's APB clock is at 30 MHz, and you have 15 time quanta (1 + 6 + 8).

ie ((30,000,000 / 4) / 15) = 500,000

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csminus
csminusAuthor
Associate II
June 24, 2015
Posted on June 24, 2015 at 19:08

0690X000006031bQAA.jpg

Tesla DeLorean
Tesla DeLorean
Guru
June 24, 2015
Posted on June 24, 2015 at 19:37

Ok, and if you lose R1 and R4 can just connect the west side to CAN-H and CAN-L of the bus, with a 120 Ohm termination between them, does that function any better?

Do you have two of these boards, and can you set them up in receive and transmit modes?

0690X000006031pQAA.jpg

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csminus
csminusAuthor
Associate II
June 24, 2015
Posted on June 24, 2015 at 19:48

i have only one, i will try to get second at the morning, Ou and i have on can out 5khz freq but on converter its a 10-60 its not stable, but when i connect devices then all loks normal

csminus
csminusAuthor
Associate II
June 25, 2015
Posted on June 25, 2015 at 10:04

I have 2 devices now, but still not working i set reciving on first and sending on second.

csminus
csminusAuthor
Associate II
June 25, 2015
Posted on June 25, 2015 at 12:12

someone have idea?

john239955_st
john239955_st
Associate III
June 25, 2015
Posted on June 25, 2015 at 17:44

Hi Not sure if this helps ...

Sometime ago I invested in a Peak PCAN View (USB) which allows you work with a known Transmitter and Receiver. You can set say 1M bit and transmit a CAN message and check timing of data on an Oscilloscope, I think 1Mbit is 1uSec, 500K is 2uSec etc.

If you have clocks etc incorrect it ususally easier to pin point the problems albeit I do struggle with CAN ... Good Luck.

KR John.W

csminus
csminusAuthor
Associate II
June 29, 2015
Posted on June 29, 2015 at 08:42

eh i dont have any ideya, nothing works, it must be hardware problem but i dont see it, this same Typ of connection works fine, but it is stm32f1xx

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