SPRUIW9C October 2021 – March 2024 TMS320F280033 , TMS320F280034 , TMS320F280034-Q1 , TMS320F280036-Q1 , TMS320F280036C-Q1 , TMS320F280037 , TMS320F280037-Q1 , TMS320F280037C , TMS320F280037C-Q1 , TMS320F280038-Q1 , TMS320F280038C-Q1 , TMS320F280039 , TMS320F280039-Q1 , TMS320F280039C , TMS320F280039C-Q1
The transmission baud rate of any node is configured by the CPU at the beginning; this defines the bit time Tbit. The bit time is derived from the fields P and M in the baud rate selection register (BRSR). There is an additional 3-bit fractional divider value, field U in the BRSR register, which further fine-tunes the data-field baud rate.
The ranges for the prescaler values in the BRSR register are:
P = 0, 1, 2, 3, . . . , 224 - 1
M = 0, 1, 2, . . . , 15
U = 0, 1, 2, 3, 4, 5, 6, 7
The P, M, and U values in the BRSR register are user programmable. The P and M dividers can be used for both SCI mode and LIN mode to select a baud rate. The U value is an additional 3-bit value determining that “aTVCLK“ (with a = 0, 1) is added to each Tbit as explained in Section 30.3.1.4.2. If the ADAPT bit is set and the LIN slave is in adaptive baud rate mode, then all these divider values are automatically obtained during header reception when the synchronization field is measured.
The LIN protocol defines baud rate boundaries as:
All transmitted bits are shifted in and out at Tbit periods.