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Can the STM32H7 transmit/receive data over SPI and UART while in sleep mode?

Associate III

I'm fairly new to low-power and sleep-mode applications of STM32H7 microcontrollers. I've been trying to read through the documentation, but I'm having trouble getting a whole picture idea of how this works, and connecting all the information from the RCC, peripheral, CPU, etc. sections.

Are the following two abilities possible? Are there any gotchas I should look out for? Do I have to select the right peripheral, like only SPI4 and SPI5 can do it? Any high level help would be very helpful!

  1. Can the STM32H7 do something like reading/writing as an SPI master and saving the data to memory though DMA in sleep mode? I want to read an ADC where the MCU is the master, without having the MCU running full blast the whole time.
  2. Same question about UART. Can it look for a certain type of packet in sleep mode, and then transmit a packet of data during sleep mode? The MCU will periodically be requested for data over UART, and then required to send a packet. Same as with the ADC, I don't want the MCU to have to be running full blast the whole time.
ST Employee

Hello @tjdyhdsfeadgstdj 

  • According to SPI, in master mode, the kernel clock is needed in order to provide the timings of the interface. However, in slave mode, it can be removed, so you can use a wakeup event signal. You don't have to select a specific instance. For further information, I would recommend checking Low-power mode management section for the SPI interface in the corresponding reference manual. 


  • According to USART, more features to manage low power modes are available, you can use a wakeup event as well. To know if the wake-up from Stop mode is supported for a given USART instance, you can check USART features table in the reference manual. Interesting recommendations are detailed in the reference manual, before entering low-power, when entering and when exiting from low-power mode.

I hope this clarifies a little bit how to dig into documentation to manage low power mode!

STM32H747/757 advanced power management - Application note This application note is provided as well to explain and help reduce power consumption. 

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