PWM signal conditioning for HIL

For an automotive HIL system we have developed a multichannel "PWM signal conditioning" with a CanOE configuration frontend.

The signal conditioning transforms a current PWM of some milliampere current swing riding on an offset based voltage PWM up to 80 V with a different frequency to a ground based voltage PWM. The ground based voltage PWM is measurable by the HIL system.

The thresholds for converting the current PWMs to voltage PWMs are configurable and configured during power-up by an STM32 microcontroller. An ADC in each PWM channel allows measurement of the current for auto configuration, controlled by the CanOE-Frontend.

The communication between STM32 and the HIL is handled by UART. Multiple signal conditions can be cascaded by UART. The UART high-level protocol is address based, the addresses can be jumpered on each board.