Datasheet

ST10F269 14 - SERIAL CHANNELS
99/184
Synchronous Mode Baud Rates
For synchronous operation, the Baud rate
generator provides a clock with 4 times the rate of
the established Baud rate. The Baud rate for
synchronous operation of serial channel ASC0
can be determined by the following formula:
(S0BRL) represents the content of the reload
register, taken as unsigned 13-bit integers,
(S0BRS) represents the value of bit S0BRS (‘0’ or
‘1’), taken as integer.
Using the above equation, the maximum Baud
rate can be calculated for any clock speed as
given in Table 30.and Table 31
Note: The deviation errors given in the Table 30 are rounded. To avoid deviation errors use a Baud rate
crystal (providing a multiple of the ASC0/SSC sampling frequency)
B
Sync
=
S0BRL = (
f
CPU
4 x [2 + (S0BRS)] x B
Sync
) - 1
f
CPU
4 x [2 + (S0BRS)] x [(S0BRL) + 1]
Table 30 : Commonly Used Baud Rates by Reload Value and Deviation Errors (PQFP144 devices)
S0BRS = ‘0’, f
CPU
= 40MHz S0BRS = ‘1’, f
CPU
= 40MHz
Baud Rate (Baud) Deviation Error
Reload Value
(hexa)
Baud Rate (Baud) Deviation Error
Reload Value
(hexa)
5 000 000 0.0% / 0.0% 0000 / 0000 3 333 333 0.0% / 0.0% 0000 / 0000
112 000 +1.5% / -0.8% 002B / 002C 112 000 +2.6% / -0.8% 001C / 001D
56 000 +0.3% / -0.8% 0058 / 0059 56 000 +0.9% / -0.8% 003A / 003B
38 400 +0.2% / -0.6% 0081 / 0082 38 400 +0.9% / -0.2% 0055 / 0056
19 200 +0.2% / -0.2% 0103 / 0104 19 200 +0.4% / -0.2% 00AC / 00AD
9 600 +0.2% / -0.0% 0207 / 0208 9 600 +0.1% / -0.2% 015A / 015B
4 800 +0.1% / -0.0% 0410 / 0411 4 800 +0.1% / -0.1% 02B5 / 02B6
2 400 0.0% / 0.0% 0822 / 0823 2 400 +0.1% / -0.0% 056B / 056C
1 200 0.0% / 0.0% 1045 / 1046 1 200 0.0% / 0.0% 0AD8 / 0AD9
900 0.0% / 0.0% 15B2 / 15B3 600 0.0% / 0.0% 15B2 / 15B3
612 0.0% / 0.0% 1FE8 / 1FE9 407 0.0% / 0.0% 1FFD / 1FFE