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External crystal fails and internal RC clock take places?

Question asked by 卢 正弘 on Jul 13, 2020
Latest reply on Jul 14, 2020 by lama

We have adopted S12ZVC as the MCU in a recent controller project.

When ESD test was conducted on the controller, the fixed cycle of the 'main' function seems to slow down, which is toggled by the RTI(real time interrupt) module. External crystal (8MHz) was selected as the source for the RTI.

The visible phenomenon was  that CAN took several times longer period to send message with uninterrupted rolling counter.

I wonder if there is some auto-shift mechanism inside the S12ZVC core that the RTI's clock shift to IRCCLK when external crystal fails without reset the MCU. If there is, how it is indicated?