Accurate or custom baudrate on nrf9160

[Chraebs]

Hi

On a nrf9160, I need to send data via UART(E) at 921600 baud. According to the UARTE BAUDRATE register documentation the register value 0xF000000 (Baud921600) leads to an actual rate of 941176 Hz. This is also what I measure on the oscilloscope. Setting the BAUDRATE register to an interpolated value 0xEBEDFA4 seems to result still in approx. 940000. What is the recommended way to achieve more accurate baudrate 921600?

Follow-up question: Is it possible to use custom baud rates, or are only the baudrates listed in the UARTE BAUDRATE register documentation supported?

Thanks,
Matthias

[vkadal]

Custom baud rate can be used, provided both the devices has the same buad rate. Even small change in the clock will result in error.  So you shall us cristal clock to have effective communication

[Chraebs]

I actually figured out, that in some situations linear interpolation between the actual values given in the BAUDRATE table lead to the expected (linear interpolated) signals. E.g. register value 0x6000000 leads to approx 380kbaud.

However, according to linear interpolation, I'd expect then that register value 0xEAFC293 would lead to 921.6kbaud but it results in a signal with 939kbaud.

Is there any value I can set in the BAUDRATE regiser which results in a signal with baudrate 921600?