note: this formula is simplified and may differ from the actual baudrate measurement
The formula is:
Baudrate = desired baudrate * 2^32 / 16000000
Example:
Baudrate of 31250 should then be 8388608 decimal = 0x800000.
Note that you will have to round the number afterwards:
rounded_value = (value + 0x800) & 0xFFFFF000
Since the baudrate generator will be sourced by the 16 M (Either RC or XOSC, depending on your configuration), then your error rate will be ~equal to the overall drift of the system clock and the accuracy of the baudrate generator towards your target baudrate.
Other way around:
Check out this define in nrf51_bitfields.h line 5702:
That specific value got me a bit puzzled.
I had a quick chat with a HW-designer, and he assured me that the baudrate generator for the UART is actually 20 bits, so rounding procedure is required.
As far as I see, the 921K600 baud definition in nrf51_bitfields.h is incorrect. I will input a bug regarding this item.
I see that this define is removed from our reference manual, so it's likely a glitch that it's still defined in the header file.
I will also push for the calculation to be inserted into our documentation.
That specific value got me a bit puzzled.
I had a quick chat with a HW-designer, and he assured me that the baudrate generator for the UART is actually 20 bits, so rounding procedure is required.
As far as I see, the 921K600 baud definition in nrf51_bitfields.h is incorrect. I will input a bug regarding this item.
I see that this define is removed from our reference manual, so it's likely a glitch that it's still defined in the header file.
I will also push for the calculation to be inserted into our documentation.
