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[#1]

Safe Mode behaviour in MPC5746C

For the Safe Mode implementation on the MPC5746C, I configured MC_ME_SAFE_MC[PDO] = 1 to enter Safe Mode.
To ensure that the output pins hold their last driven state during the transition, I configured the SIUL2[SMC] (Safe Mode Control) bit = 1.

With this configuration, the digital output (GPIO) pins successfully retain their previous state in Safe Mode.

However, in my safety application, I use a PWM output (eMIOS) to control a light, and my requirement is to keep the predefined duty cycle active when entering Safe Mode.
If I use SIUL2[SMC] = 1, the PWM output pin does not retain its previous duty cycle value after entering Safe Mode.

Question:

• What is the recommended method to retain or emulate the last PWM duty cycle state when entering SAFE mode?

• Or, is it advisable to switch from PWM to GPIO and drive a predefined static value (ON/OFF) before entering Safe Mode?

Re: Safe Mode behaviour in MPC5746C

Hello,

eMIOS PWM outputs do not retain their duty cycle when entering Safe Mode, even with SIUL2[SMC] set.

This is because eMIOS modules are typically disabled in Safe Mode unless explicitly configured otherwise, and Safe Mode is designed to minimize power and functionality for safety recovery.

However, in my safety application, I use a PWM output (eMIOS) to control a light, and my requirement is to keep the predefined duty cycle active when entering Safe Mode.
If I use SIUL2[SMC] = 1, the PWM output pin does not retain its previous duty cycle value after entering Safe Mode.

Is eMIOS clock source is still valid in Safe Mode?

What is the recommended method to retain or emulate the last PWM duty cycle state when entering SAFE mode?

Or, is it advisable to switch from PWM to GPIO and drive a predefined static value (ON/OFF) before entering Safe Mode?

Switch to GPIO mode before entering Safe Mode. Drive the pin with a static value that approximates the desired light intensity (e.g., ON for high duty cycle, OFF for low). This is simple, predictable, and aligns with Safe Mode’s intent.

Consider reconfiguring the eMIOS module to remain active in Safe Mode.

Best regards,

Peter