CY8C4147AZI-S475 clock config for CAN bus

[willrow]

Hello,

I am having some problems in setting up the CAN bus on my CY8C4147AZI-S475 MCU.

I think my issue is configuring the clock correctly.  As far as I can see in order to get the accuracy required to run CAN at 500 kbps I should have a clock accuracy of less than +/- 0.5%, but the native clock is +/- 2%. The data sheets mention using the more accurate WCO to help configure this but I cannot see how to do this.

Any help would be much appreciated.

[Alakananda_BG · Accepted solution]

Hi,

Can you please ensure the following points?

1. Set the IMO clock frequency to the correct SysClk frequency for 1 Mbps clock speed to work. This is documented in the PSOC 4200 M architecture TRM, Pg 192, See figure Figure 17-12. Bit Rate Versus SYSCLK.

2. WCO in the Low frequency tab, ensure that you have connected external WCO to the right pins.

3. Ensure that you set the Trim with option to WCO in the IMO section of the clock configurator.

I have attached a project that uses 48 MHz sysclk and I see activity on the Tx line. Please check.

Regards,

Alakananda

[B4SuraniTG0]

Dear Alakandanda_BG

I work with Willrow, we already have a PCB ready without Crystal, is there a way of running CAN without an external WCO? It is okay to run it at a slower speed/baud rate. Here I attached a project datasheet, kindly let us know if there is a way.

Thank you in advance. 

[Alakananda_BG]

Hi @B4SuraniTG0 ,

Can you please create a new thread so that we can continue the discussion there.

Regards