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STM32L0 with HSI for UART

MKanc.1
Associate III

I have built a board that is powered using a LiC and to conserve some power i run it under 1MHz (524KHz).

I need 2 UARTs and one ADC for my application. However, since there's only 1 LPUART i use second UART to connect a cheap BLE module that i can separately power as needed.

I can keep module unpowered however UART connection under 1MHz drops below 115200 ratio which i want to use. As a second option, i can use HSI 16MHz and lower it to 4MHz to reach 115200.

I disable UART if i don't need it. I noticed it consumes power over tx/rx somehow.

Same applies with ADC, but i don't need rapid readings from it thus keeping it sync with cpu.

I am curious how it would affect consumption if i use HSI for UART. Is there any paper explaining this consumption? I keep it 9600 baud now, but if it consumes 10uA or something, i can use async HSI for UART as well.

I do not use anything but MSI+LSE for this application, but consumption after enabling HSI for UART, or maybe HSI for ADC is my question.

I can measure power using tools, but i am curious about technical details.

3 REPLIES 3

This?

waclawekjan_0-1731424691872.png

JW

Yes thank you, this one plus the extra if it is used as a source to UART or ADC

Andrew Neil
Evangelist III

@MKanc.1 wrote:

to conserve some power i run it under 1MHz (524KHz).


Often it's better for low power consumption to run quickly and sleep more ...