28.4.2.1.1 Asynchronous Arithmetic Mode BAUD Value Selection

The formula given for f_BAUD calculates the average frequency over 65536 f_ref cycles. Although the BAUD register can be set to any value between 0 and 65536, the actual average frequency of f_BAUD over a single frame is more granular. BAUD register values that affect the average frequency over a single frame result in an integer increase in the cycles per frame (CPF).

C P F = \frac{f_{r e f}}{f_{B A U D}} (D + S)

where

D represents the number of data bits per frame
S represents the sum of the start bit and the first stop bit, if present

Table 28-2 shows the BAUD register value versus baud frequency f_BAUD at a serial engine frequency of 48 MHz. This assumes a D value of eight bits and an S value of two bits (ten bits, including start and stop bits).

Table 28-2. BAUD Register Value vs. Baud Frequency
BAUD Register Value	Serial Engine CPF	f_BAUD at 48 MHz Serial Engine Frequency (f_REF)
0 – 406	160	3 MHz
407 – 808	161	2.981 MHz
809 – 1205	162	2.963 MHz
...	...	...
65206	31775	15.11 kHz
65207	31871	15.06 kHz
65208	31969	15.01 kHz