TCAN4550-Q1: How can set at 8Mbps data rate?

Asaishi-san,

The TCAN4550-Q1 Software User's Guide has a section over this, I'd recommend reading through this document prior to trying any kind of CAN communication on the TCAN4550-Q1.

The data rate is configured by writing to registers 0x100C and 0x101C. These registers configure the time quanta per bit based on the oscillator frequency. For 8Mbps, a 40MHz clock will need to be used. Each bit is subdivided into time quanta, and these can be configured in the NBTP and DBTP registers. There is much more detail in the Software User's Guide, so again, I would recommend reading through that document, and if you have further questions please feel free to bring them back to this thread.

Regards,

Hi Eric,

CAN data rate is calculated by clock frequency / (tq/bit) according to the user's guide at page 7.
Clock frequency will be 40MHz so the tq/bit should be 5tq/bit to achieve 8Mbps, right? (if counter prescaler is set as 0x0 by DBRP[4:0] of 0x100C)

How can the tq/bit be adjusted?
I couldn't find any related description on 0x100C and 101C register to be able to change tq/bit.
I guess Fig6 of user's guide indicated the value of tq/bit is fixed as 10bit.

I have another question, TCAN4550EVM can communicate with MSP430FR6989 board such a below E2E question.
e2e.ti.com/.../3266312
And you provide TCAN4550 demo software (rev.B).
What demo can the software realize?
I want to know the benefit of the software so that I couldn't read the software code.

Best regards,
Koyo

Asaishi-san,

Thank you for this information, I'll have a response for you tomorrow.

Regards,

Asaishi-san,

To adjust the tq/bitt you have to configure Prop + Phase 1 and Phase 2 portions to add up to 5 time quanta, which will give you 8Mbps. These can be configured in registers 0x100C and 0x101C. There are bits to configure the amount of time quanta before and after the sample point. For the 8Mbps configuration, 3 time quanta before the sample point, and 2 time quanta after the time quanta with no prescaler would be the settings needed. 

The demo code is starter code to give the user an easy way to learn how to configure different functions of the device in a succinct way. The benefit is having a structure and outline to transmit and receive CAN frames, configuring watchdog, state changes, etc. The demo software is available on the TCAN4550-Q1 product folder.

Regards,

Hi Eric,

To achieve 8Mbps, should I set the NBRP to 0x000?
I can't understand each bit difference because there are no detailed description.

Best regards,
Koyo