The control board integrates a motor drive circuit and a microcontroller-based control circuit. When switching the power devices, a reset occurred on the microcontroller.
Please answer the following questions based on the situations described below.
Situation 1: Behavior at Power-On When the power was turned on, after the POR was released, MCU_RESETSTATz and RESETSTATz rose in sequence (Fig.1).
Additionally, the clock signal (green) for the delta-sigma module is output from the PRU core, but it starts about 2.5 seconds after the microcontroller reset occurs (Fig.2).
Situation 2: When Switching Operation Starts
Immediately after switching started, a reset occurred (Fig.3).
At the same timing as the reset was released, the clock signal (green) for the delta-sigma module started operating (Fig. 4).
(PWM is also output in conjunction with switching, resulting in irregular behavior.)
Question 1
Under what conditions does a reset occur where MCU_RESETSTATz, PORz_OUT, and RESETSTATz all fall and rise at the same timing?
Also, based on the above situation, it seems that the microcontroller’s internal software processing is temporarily halted during the reset. If there are conditions under which such a phenomenon occurs in the microcontroller, please let me know.
Question 2
Please tell me how to avoid unintended resets like the above, or what countermeasures can be taken when they occur.
