C8051F52X_12 Datasheet, PDF (166/221 Pages) Silicon Laboratories – 8/4/2 kB ISP Flash MCU Family

C8051F52x/F53x
Table 17.1. Baud-Rate Calculation Variable Ranges
Factor
prescaler
multiplier
divider
Range
0…3
0…31
200…511
Important: The minimum system clock (SYSCLK) to operate the LIN peripheral is 8 MHz.
Use the following equations to calculate the values for the variables for the baud-rate equation:
multiplier = -------2---0---0---0---0------- – 1
baud_rate
prescaler = ln -_--_m-----_u---_l--_t--_i--_p---_l--_i--_e---_r----+---^S--1--^Y--_-^S--_--^C---_b-^L--_a--^K--_u---_d---_----_r--_a----_t--_e----_-----2---0---0-
 ---1---- – 1
ln2
divider
=
-----------------------------------------------^S----^Y---^S----^C----^L----^K-------------------------------------------------
2^{prescaler + 1}  multiplier + 1  baud_rate
It is important to note that in all these equations, the results must be rounded down to the nearest integer.
The following example shows the steps for calculating the baud rate values for a Master node running at
24.5 MHz and communicating at 19200 bits/sec. First, calculate the multiplier:
multiplier = ^{2----0---0---0---0-} – 1 = 0.0417  0
19200
Next, calculate the prescaler:
prescaler
=
l n _---0----+-----1---2-_--4-_--5---10---90---20---00---00-----_----2---0---0--
 ---1---- – 1
ln2
=
1.674  1
Finally, calculate the divider:
divider
=
-------------------2---4---5---0---0---0---0---0--------------------
2^{1 + 1}  0 + 1  19200
=
319.010  319
These values lead to the following baud rate:
baud_rate
=
----------------2---4---5---0---0---0---0---0-----------------
2^{1 + 1}  0 + 1  319

19200.63
166
Rev. 1.4