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PSoC 5, 3 & 1 MCU

Anonymous
Not applicable

 I would like to suggest a feature that would allow multiple configurations to be set up through the customizer.  In an automotive CAN application, it is required to try 2 different baud rates and 11 bit and 29 bit ID format.  It is difficult to work with the CAN_RX_CFG and CAN_TX_CFG structs to reinitialize the CAN mailboxes with different values for switching between the 11 and 29 bit ID formats.

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ShopithamR_26
Employee

 Hi,

   

You dont have to change the CAN_RX_CFG and CAN_TX_CFG structs to change the baud rate or IDE . You can directly write to the CAN register to do the same 

   

Changing Baud Rate     

   

The Bridge allows to you operate in one of the following Baud rates 1000, 800, 500, 250, 125, 62.5, 20 and 10 Kbps. Though the CAN protocol does not have any limitation on the Baud rate, these are the standard values this project currently supports. The default Baud rate is 1000 Kbps.    

   

    

          

   

To change the Baud rate you need to modify the PreScaler value and time segment values of the CAN component. Below is the simple code snippet showing the same.    

   

    

          

   

if(CAN_SetPreScaler(BRP)==CYRET_SUCCESS)     

   

CAN_SetTsegSample(tseg1,tseg2,sjw,sample_mode);    

   

    

          

   

The following table gives you the values of the BRP, tseg1, tseg2, sjw and sample modes for the various Baud rates supported in this project.    

   

    

          

   

 

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

Baud Rate (Kbps)         

BRP         

Tseg1         

Tseg2         

SJW         

Sample mode         

1000         

0x01         

0x08         

0x01         

0x00         

0x00         

800         

0x01         

0x0B         

0x01         

0x00         

0x00         

500         

0x02         

0x0C         

0x01         

0x00         

0x00         

250         

0x05         

0x0C         

0x01         

0x00         

0x00         

125         

0x0B         

0x0C         

0x01         

0x00         

0x00         

62.5         

0x17         

0x0C         

0x01         

0x00         

0x00         

20         

0x4A         

0x0C         

0x01         

0x00         

0x00         

10         

0x95         

0x08         

0x01         

0x00         

0x00         

   

 

   

Regards,

   

Sobi

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ShopithamR_26
Employee

 Hi Peter,

   

You can also change the IDE through register write.

   

Changing the IDE and RTR Bit Field     

   

    

          

   

To set or clear the IDE and RTR bit fields you need to modify the CAN TX CMD register. The CAN Component has 8 TX mailbox and each mailbox has on TX CMD register defined. This TX CMD register is 32 bit register in which bit 20 and 21 corresponds to the IDE and RTR respectively.  By writing to TX CDM register you can set as well clear the IDE and RTR bits. The following #defines will allow you to do that    

   

    

          

   

/* Set the IDE for a particular mailbox */     

   

CAN_SET_TX_IDE(Mailbox_No);     

   

/* Clear the IDE for a particular mailbox */     

   

CAN_CLEAR_TX_IDE(Mailbox_No);     

   

    

          

   

/* Set the RTR for a particular mailbox */     

   

CAN_SET_TX_RTR(Mailbox_No);    

   

/* Clear the RTR for a particular mailbox */     

   

CAN_CLEAR_TX_RTR(Mailbox_No);

   

     

Regards,
Sobi

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