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Eugenia Suarez
Associate III
March 20, 2017
Question

Bank filter confinguration working ramdonly with HAL_CAN over STM32L4

  • March 20, 2017
  • 1 reply
  • 2526 views
Posted on March 20, 2017 at 18:28

Working with HAL_CAN over STM32L4 polatform and kvaser (can analyzer).

I have this functions implementing my bank filtering:

void DRV_CAN_configureFiltersBank(void)

{

HCANFilter_Struct.FilterNumber = 0; //0 - 27

HCANFilter_Struct.FilterMode = CAN_FILTERMODE_IDMASK;

HCANFilter_Struct.FilterScale = CAN_FILTERSCALE_32BIT;

/*iid mask = 0...0 --> 0=don't care --> se acepta id con cualquier valor de bit en ese lugar*/

HCANFilter_Struct.FilterIdHigh = 0x0000; //11-bit ID in top bits ;//MSB of 32b config

HCANFilter_Struct.FilterIdLow = 0x1F;//LSB of 32b config

HCANFilter_Struct.FilterMaskIdHigh = 0x0000; //MSB

HCANFilter_Struct.FilterMaskIdLow = 0x11; //LSB

HCANFilter_Struct.FilterFIFOAssignment = 0;

HCANFilter_Struct.FilterActivation = ENABLE;

HCANFilter_Struct.BankNumber = 13;

if (HAL_CAN_ConfigFilter(&HCAN_Struct,&HCANFilter_Struct) != HAL_OK)

{

DrvCan_Error_Handler();

}

}

I would like to remark black letters. Since I have this configuration and I'm sending frames with different ID values and controller seems to get sometimes expected frames ID, but sometimes get non expected ones. Even sometimes ahs blocked correct IDs. If I understand correctly, with this configuration I have: 

  • 0x0000001F = ID value = 11111
  • 0x00000011 = mask value = 10001
  • That means all ID numbers with 1xxx1 bits at the same position will pass, but if first 1 or last one is not present that frame will not entering to my FIFO.

Is it?

The thing is that I send a frame with 10100 = ID, but this frame passes the filters and it is processed (with an eco transmition after being receiving).

Is something wrong at my configuration understanding?

Thanks in advance.

#mask #id-filters #hal_can_receive_it #can #can-filter
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1 reply

Tesla DeLorean
Guru
March 20, 2017
Posted on March 20, 2017 at 21:02

X & 10001 will never equal 11111

X & 11111 can equal 10001

Remember what the mask is describing

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Tesla DeLorean
Guru
March 20, 2017
Posted on March 20, 2017 at 21:05

HCANFilter_Struct.FilterIdHigh = ID << 5; //11-bit ID in top bits ;//MSB of 32b config

HCANFilter_Struct.FilterIdLow = 0;//LSB of 32b config

HCANFilter_Struct.FilterMaskIdHigh = 0x7FF << 5; //MSB

HCANFilter_Struct.FilterMaskIdLow = 0; //LSB
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