HSI calibration

AN3258

12/16

Doc ID 17825 Rev 1

In Figure 5, the software example has been implemented with (LDUM = 0). After the LIN

reception of the LIN header interrupt and the execution of the calibration routine, the LDIV is

loaded with LDIV_NOM by writing the LINUART_BRR1.

Figure 5.

LDIV read/write operations when LDUM = 0

In the case of LDUM = 1 (see Figure 6), the LDUM bit has to set by software before the LIN

checksum reception. In this way, the LDIV_NOM is loaded into LDIV at the end of character

reception.

Figure 6.

LDIV read/write operations when LDUM = 1

LDIV

LDIV_NOM

Baud rate

Read LINUART_BRR1

Write LINUART_BRR2

Update

at end of

synch field

LDIV[3:0]

LDIV[11:4]

LDIV_MEAS

Write LINUART_BRR1

Read LINUART_BRR2

generation

LIN sync field

measurement

Write

LINUART_BRR1

LDIV[15:2]

LDIV[3:0]

LDIV[7:0]

LDIV[15:12]

LDIV[3:0]

LDIV[11:4]

LDIV[15:12]

LDIV

LDIV_NOM

Baud rate

Read LINUART_BRR1

Write LINUART_BRR2

Update

RXNE=1

at end of

synch field

LDIV_MEAS

Write LINUART_BRR1

Read LINUART_BRR2

generation

LIN sync field

measurement

LDUM is reset

LDIV[3:0]

LDIV[11:4]

LDIV[15:12]

LDIV[3:0]

LDIV[11:4]

LDIV[15:12]

LDIV[3:0]

LDIV[11:4]

LDIV[15:12]