25.6.2.3.1 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)

CPF=freffBAUD(D+S)

where

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

Table 25-3 shows the BAUD register value versus baud frequency fBAUD at a serial engine frequency of 48MHz. This assumes a D value of 8 bits and an S value of 2 bits (10 bits, including start and stop bits).

Table 25-3. BAUD Register Value vs. Baud Frequency
BAUD Register ValueSerial Engine CPFfBAUD at 48MHz Serial Engine Frequency (fREF)
0 – 4061603MHz
407 – 8081612.981MHz
809 – 12051622.963MHz
.........
652063177515.11kHz
652073187115.06kHz
652083196915.01kHz