STM32U575CGU3 CAN Cycle Time Issue

[sasmitjoshi5]

I am using the STM32U575CGU3 MCU in my project, where I transmit data using two CAN frames on the bus. I have configured a CAN transmission cycle time of 250 ms in my software.

However, on a few PCB assemblies, I am observing inconsistencies in the transmission cycle time. On few boards, the cycle time appears to fluctuate (e.g., around 0.5–0.6 ms deviation), while on other boards, it works well.

Could you please help me understand what might be causing this variation across different PCBAs? Any guidance on potential root causes or debugging approaches would be highly appreciated.

[mƎALLEm]

Hello,

How are you managing that "cycle time"? using HAL_Delay in a loop? or over a timer interrupt? using a crystal instead of one of the internal RC clock sources?

But 0.5 to 0.6ms deviation vs 250ms between frames seems to be acceptable 0.24% of deviation!