minimum baud rate nrf52832

RE: minimum baud rate nrf52832

hmolesworth — Thu, 18 Dec 2025 19:34:36 GMT

There is no documented information as far as I am aware; I deduced the calculation from hands-on testing of the hardware. The implication is that this is not an official Nordic-supported feature; it works though.

Edit: iosonata by Hoang Nguyen has some further information on testing the calculation here: iosonata - uart_nrfx.cpp

RE: minimum baud rate nrf52832

haoren1101 — Thu, 18 Dec 2025 07:13:50 GMT

Hello, may I ask where you saw this calculation method? I couldn't find any relevant information in the data sheet of nRF52832.

RE: minimum baud rate nrf52832

hmolesworth — Sun, 20 Aug 2023 03:05:19 GMT

I disagree; many baud rates are possible, try playing with this:

// Baudrate generator for the UART is the top 20 bits of a 32-bit field; add in rounding 0.5 ls bit
 uint32_t RequiredBaudRate = 600; // whatever ..
 uint32_t CalculatedRegisterValue;
 uint64_t SystemClock = 16000000ULL;    // Typically 16MHz
 uint64_t MagicScaler = 32; // Preserves bits on divisions, shift 32 bits
 CalculatedRegisterValue = (uint32_t)(((((uint64_t)RequiredBaudRate << MagicScaler) + (SystemClock>>1)) / SystemClock) + 0x800) & 0xFFFFF000;

Did you know that with a screened twisted-pair cable using RS485 (easy on nRF52) it is possible to transmit a distance of 4 miles at 1200 baud or less? Don't ask, once I had to do just that ...

RE: minimum baud rate nrf52832

Raoul — Fri, 18 Aug 2023 18:50:24 GMT

Happy to help!

Best regards,

Raoul

RE: minimum baud rate nrf52832

StanislavDimitrov — Fri, 18 Aug 2023 08:15:28 GMT

Thanks a lot, Raoul, SoftwareSerial from Arduino could be a good starting point. Your links about are really helpful!

RE: minimum baud rate nrf52832

Raoul — Fri, 18 Aug 2023 07:42:45 GMT

The peripheral doesn't support it. But if you want to "bit-bang" UART by just toggling GPIOs in software, less than 1200 is surely possible :-)

If you really want to do that, I think there must be some library you could use somewhere on the internet. I doubt that you'll have to implement the UART logic from scratch.

Best regards,

Raoul

RE: minimum baud rate nrf52832

StanislavDimitrov — Fri, 18 Aug 2023 06:02:01 GMT

So by playing with the clock speed or low-level counters, less than 1200 bps cannot be achieved?

RE: minimum baud rate nrf52832

Raoul — Thu, 17 Aug 2023 22:03:49 GMT

Hi Stanislav,

The minimum baud rate is 1200. See the infocenter.

You can set it by creating a devicetree overlay with a uart node, and then setting the "current-speed" parameter. See this, for example.

The options for that parameter are actually defined here: https://github.com/nrfconnect/sdk-zephyr/blob/main/dts/bindings/serial/nordic%2Cnrf-uart-common.yaml

If you don't know what a devicetree overlay is yet, I recommend this section of our Dev Academy: https://academy.nordicsemi.com/courses/nrf-connect-sdk-fundamentals/lessons/lesson-2-reading-buttons-and-controlling-leds/topic/devicetree/

Going through the entire nRF Connect Fundamentals course is highly recommended, by the way.

(I'm assuming you are using the nRF Connect SDK, based on your previous cases)

Best regards,

Raoul