My PVD (Programmable Voltage Detector) don’t work

[Terje Bøhler]

Hi.

I want my MCU (STM32F107VCT6) to generate an interrupt when the Vdd is below (e.g.) 2.9V. I have implemented the following init-code:

PWR->CR  = PWR_CR_PLS_2V9;  // 2.9V
mcu_reg  = PWR->CR;
PWR->CR |= PWR_CR_PVDE;     // Bit 4 PVDE: Power voltage detector enable.
mcu_reg  = PWR->CR;   
 
// For test purposes only ...
// Bit 2 PVDO: PVD output
// This bit is set and cleared by hardware. It is valid only if PVD is enabled by the PVDE bit.
// 0: VDD/VDDA is higher than the PVD threshold selected with the PLS[2:0] bits.
// 1: VDD/VDDA is lower than the PVD threshold selected with the PLS[2:0] bits.
mcu_reg  = PWR->CSR;  
       
NVIC_EnableIRQ(PVD_IRQn);           // Uses EXTI line 16

Q1: When I run (Keil uV5 and ULINK2) the above init-code, I always read back 0 from both the registers above (as if the contents written is not actually written into the register). Why?

Q2: When I run my application the PVDO-bit is never set, even when the Vdd is below 2.5V. Why?

Q3: It seems like the “PVDO�? bit is not enebled (it is “shaded�? (see below)). Why?

[Tesla DeLorean]

Is PWR/BKP enabled and UNLOCKED?

[Terje Bøhler]

Thanks Clive.

Which registers are you referring to?

My "RM0008 Reference manual" is not very specific, and I do not have an example project for this PVD-feature. I would very much appreciate if you could be more specific.

Q1: Is it a RCC->APB1ENR |= RCC_APB1ENR_PWREN you are referring to (that's missing)?

Q2: Which register performs the "UNLOCK"?

Q3: The BKP is "Backup Register"???

I very much appreciate som further clarifications to this matter.

BR Terje