1.7.1 Baud Rate Rounding Errors

Table 1-2. UART Primary Baud Rates
Desired Rate (bps)	Actual Rate (bps)	% Error
921600	914285.71	-0.8%
2400	2400	0.00%
4800	4800	0.00%
9600	9600	0.00%
19200	19200	0.00%
38400	38400	0.00%
57600	57588.48	-0.02%
115200	115107.91	-0.08%
230400	230215.83	-0.08%
460800	459330.14	-0.32%

CAUTION: The percentage error is calculated assuming the 24 MHz clock source is stable. Any drift in the source clock frequency would affect the percentage error.

The actual baud rate is calculated as follows:

A c t u a l R a t e = \frac{64 * 24 M H z}{16 * c e i l i n g (x)}

Where,

x = \frac{64 * 24 M H z}{16 * D e s i r e d R a t e}

Example: For 115,200 bps,

x = (64 × 24,000,000) / (16 × 115,200) = 86.805... x_rounded = 87

Actual Rate = (64 × 24,000,000) / (16 × 87) = 115,107.91 bps

Error = -0.08%