Dealing with crystal failure for MPC57XX

The MPC57XX system-on-chip (SoC) includes a set of highly flexible modules that provide a large portfolio of internal and external clock sources. In general, crystal devices for car-mounted equipment serve in extreme and more severe conditions than in other applications. Accordingly, they are designed to ensure high reliability. However, when using external crystals or external clock sources, there is always a possibility of the source failing while the application is running. The clock fail detection logic on the MPC57XX SoCs detects clocking failures of the external crystal circuit (XTAL) on the application board but it does not automatically switch to the internal crystal oscillator circuit (IRCOSC) as the clock source. This application note discusses the ways in which loss of clock due to external oscillator (XOSC) failure can be handled correctly through software.

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Originally published by Freescale Semiconductor at www.freescale.com as "Handling Crystal Failure for MPC57XX".