CAN Bus Transceivers problem

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asdasd
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CAN Bus Transceivers problem

Postby asdasd » Thu Dec 31, 2020 9:31 am

Hi ,
I have connect cjmcu-230(SN65HVD23x) with stm32f103cb with flowing connection
Image
then I modified the can test hal example to disable CAN_BTR_LBKM and change the baud-rate

Code: Select all

static const CANConfig cancfg = {
  CAN_MCR_ABOM | CAN_MCR_AWUM | CAN_MCR_TXFP,
   CAN_BTR_SJW(0) | CAN_BTR_TS2(1) |        //CAN_BTR_LBKM |
  CAN_BTR_TS1(8) | CAN_BTR_BRP(35)
};


Then i set :
-GPIOA12 ---->Alternate_pushpull .
-GPIOA11 ---->input _pullup .

But when I test the signal on CTX there is available packet output but it is disappear in CANH,CANL.
can any body advice me what to do ?

best regard,
asd

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Giovanni
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Re: CAN Bus Transceivers problem

Postby Giovanni » Thu Dec 31, 2020 11:19 am

Hi,

Is the transceiver actually powered up? do you have termination resistors?

Giovanni

asdasd
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Re: CAN Bus Transceivers problem

Postby asdasd » Thu Dec 31, 2020 11:27 am

Giovanni wrote:Hi,

Is the transceiver actually powered up? do you have termination resistors?

Giovanni


yes the transceiver is powered on(3.3v) . and the termination resistors is in the schematic:
Image

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Re: CAN Bus Transceivers problem

Postby steved » Thu Dec 31, 2020 11:13 pm

a) Managed to avoid the STM32F1xx series, but on other ST devices both GPIO pins would need to be set to an alternate mode. (That seems to force the direction, but not necessarily output type, pullups etc).
b) Does the 3.3V supply on your processor card have enough spare to power the CAN card? Bear in mind that the CAN driver will take short spikes of current (3.3V across 60 ohms is >50mA, if both ends of the line are terminated), even though the average current may only be a few mA. And it bothers me that there's no decoupling on the CAN transceiver power supply.
c) How are you checking for signal on the CANH and CANL Lines?
d) Have you tried checking your software in CAN loopback mode to see what's happening?
e) Have others used the hardware combination successfuly?


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