31.6.2.3.1 Asynchronous Arithmetic Mode BAUD Value Selection

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

C P F = f r e f f B A U D ( D + S )

Where,

  • D represent the data bits per frame
  • S represent the sum of start and first stop bits, if present.

The following table shows the BAUD register value versus baud frequency fBAUD at a serial engine frequency of 48 MHz. This assumes a D value of 8 bits and an S value of 2 bits (10 bits, including start and stop bits).

Table 31-3. BAUD Register Value vs. Baud Frequency
BAUD Register Value Serial Engine CPF fBAUD at 100 MHz Serial Engine Frequency (fREF)
0 – 406 161 6.211 MHz
407 – 808 162 6.211 MHz
809 – 1205 163 6.173 MHz
... ... ...
65206 31775 31.47 kHz
65207 31872 31.38 kHz
65208 31969 31.28 kHz