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Associate II
March 17, 2026
Solved

STM32U073CCT6 - True random-number generator (RNG) and STOP MODE

  • March 17, 2026
  • 1 reply
  • 133 views

Hi

 

I would like to check if it is necessary to call MX_RNG_Init() after the MCU exits STOP MODE to reconfigure the RNG?

 

BR

Gilberto

Best answer by Gyessine

Hello @gilberto-falker 
Stop mode achieves the lowest power consumption while retaining the content of SRAM and registers. All clocks in the VCORE domain are stopped, the PLL, the MSI RC, the HSI16 RC and the HSE crystal oscillators are disabled
and since The RNG runs on two different clocks which one of them is the AHB bus in the STM32U073
what really matters is that you call the  SystemClock_Config(); just after exiting stop mode.
you can also track the RNGEN bit in the RNG_CR register and the DRDY bit in the RNG_SR register
BR
Gyessine

1 reply

GyessineBest answer
Technical Moderator
March 18, 2026

Hello @gilberto-falker 
Stop mode achieves the lowest power consumption while retaining the content of SRAM and registers. All clocks in the VCORE domain are stopped, the PLL, the MSI RC, the HSI16 RC and the HSE crystal oscillators are disabled
and since The RNG runs on two different clocks which one of them is the AHB bus in the STM32U073
what really matters is that you call the  SystemClock_Config(); just after exiting stop mode.
you can also track the RNGEN bit in the RNG_CR register and the DRDY bit in the RNG_SR register
BR
Gyessine

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