UART Baud Rate Calculator
Calculate UART bit timing, actual baud rate from divider settings, and baud rate error.
Typically 16 for UART
Baud Rate Divider
9
Baud Rate Divider vs Peripheral Clock
UART Baud Rate Generation
UART baud rate is derived from the peripheral clock using an integer divider and oversampling.
Formula
Divider = round(Clock / (Oversampling x Baud Rate))
Actual Baud = Clock / (Oversampling x Divider)
Error = Actual - Desired
Baud rate error should stay below 2% for reliable communication. Errors above 3-5% cause framing errors, especially for multi-byte transfers.
Example Calculation
16 MHz clock, 115200 baud, 16x oversampling.
- 01Exact divider: 16e6 / (16 x 115200) = 8.68
- 02Integer divider: round(8.68) = 9
- 03Actual baud: 16e6 / (16 x 9) = 111,111 baud
- 04Error: |111111 - 115200| / 115200 = 3.55%
- 05This is marginal; consider a different clock frequency
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