STM8S datasheet(354/467 Pages) STMICROELECTRONICS

354 / 467 page

Universal asynchronous receiver transmitter (UART)

RM0016

354/467

DocID14587 Rev 14

LHE is set if one of the following conditions occurs:

•

Break Delimiter is too short

•

Synch Field is different from 55h

•

Framing error in Synch Field or Identifier Field

•

A LIN header reception time-out

Note:

If a LIN header error occurs, the LSF bit in the UART_CR6 register must be cleared by

software

LIN header time-out error

The UART automatically monitors the THEADER_MAX condition given by the LIN protocol.

If the entire Header (up to and including the STOP bit of the LIN Identifier Field) is not

received within the maximum time limit of 57 bit times then a LIN Header Error is signaled

and the LHE bit is set in the UART_SR register.

Figure 134. LIN header reception time-out

The time-out counter is enabled at each break detection. It is stopped in the following

conditions:

•

A LIN Identifier Field has been received

•

An LHE error occurred (other than a time-out error).

•

A software reset of LSF bit (transition from high to low) occurred during the analysis of

the LIN Synch Field

If LHE bit is set due to this error during the LIN Synch Field (if LASE bit = 1) then the UART

goes into a blocked state (the LSF bit is set).

If LHE bit is set due to this error during Fields other than LIN Synch Field or if LASE bit is

reset then the current received Header is discarded and the UART searches for a new

Break Field.

Note on LIN Header time-out limit

According to the LIN specification, the maximum length of a LIN Header which does not

cause a time-out is equal to:

1.4 * (34 + 1) = 49 TBIT_MASTER.

TBIT_MASTER refers to the master baud rate.

STM8S Datasheet(PDF) 354 Page - STMicroelectronics