How to use Low Power UART (LP UART) baud rate compensation?

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a_ziliu
Posts: 207
Joined: 20 Mar 2017, 10:52

31 May 2021, 15:52

User can set the bit to be compensated using BRCOMP (UART_BRCOMP [8: 0]) and set the positive or negative compensation using BRCOMPDEC (UART_BRCOMP [31]) to increase or decrease the bit data time by 1 UART clock.
Low Power UART register


Example
UART peripheral clock = 32.768K (LXT)
UART Baud rate = 9600, 1bit = 104.167us

The original waveform represents 1 bit UART data ( (1 / 32.768K) * 3 = 91.55us) according to 3 UART clocks. The waveform is as follows:

The register setting is as follows:
BRCOMP[8:0] = 0x0010100101
BRCOMPDEC[31] = 0
1 UART clock time compensated at bit0, bit2, bit5, bit7 = ((1/32.768K) * 4 = 122.07us)
The waveform is as follows:

When the compensation function is enabled, the UART baud rate error can be controlled within ± 0.5 UART clock.

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