Posted on March 02, 2017 at 19:19 Hi
Paraskevopoulos.Pana
,
Regarding your first question:
Correct, the Reset uses a negative logic.
Regarding your second question:
- For the STM32 to successfully operate, the supplied voltage must always stay above the minimum voltage level specified by the product datasheet(1.8 V in this case).When supplied voltage drops below this level, the STM32 MCU internal circuitries are operating out of specification.This may lead to an unexpected behavior.To prevent this, a dedicated circuitry called POR/PDR is integrated to the MCU: the circuitry maintains the MCU under reset.
- For some applications, the user needs to prevent the whole application from operating when the power supply is below an application_specific voltage (higher than the 1.8V). In typical designs, the user would need to use a brown-out descret IC like STM682Xto make this function.Fortunatelly, an STM32-MCU-based application will note need such IC since it's already embedded inside the MCU.
The Brown Out Reset is a way to keep the MCU under reset until the supply voltage reaches a specified VBOR threshold set by the user.
The STM32F401 device have 3 possible BOR values, which are described in the datasheet.
Additional information:
The STM32 devices have an embedded programmable voltage detector(PVD). It monitors the VDD/VDDA power
supply, compares it to the PVD threshold and generate an interrupt when the VDD/VDDA voltage drops below/is higher than the PVD threshold.
You can refer to the datasheet and the reference manual for further details.
Khouloud.
