Atmel Evaluation Kit AT91SAM9G25-EK AT91SAM9G25-EK Data Sheet

813

SAM9G25 [DATASHEET]

11032C–ATARM–25-Jan-13

This mode is useful only for Master nodes. It respects the following rule: each frame slot shall be longer than or equal to
TFrame_Maximum.

If the Frame Slot Mode is enabled (FSDIS = 0) and a frame transfer has been completed, the TXRDY flag is set again
only after TFrame_Maximum delay, from the start of frame. So the Master node cannot send a new header if the frame
slot duration of the previous frame is inferior to TFrame_Maximum.

If the Frame Slot Mode is disabled (FSDIS = 1) and a frame transfer has been completed, the TXRDY flag is set again
immediately.

The TFrame_Maximum is calculated as below:

If the Checksum is sent (CHKDIS = 0):

z

THeader_Nominal = 34 x Tbit

z

TResponse_Nominal = 10 x (NData + 1) x Tbit

z

TFrame_Maximum = 1.4 x (THeader_Nominal + TResponse_Nominal + 1)

z

TFrame_Maximum = 1.4 x (34 + 10 x (DLC + 1 + 1) + 1) x Tbit

z

TFrame_Maximum = (77 + 14 x DLC) x Tbit

If the Checksum is not sent (CHKDIS = 1):

z

THeader_Nominal = 34 x Tbit

z

TResponse_Nominal = 10 x NData x Tbit

z

TFrame_Maximum = 1.4 x (THeader_Nominal + TResponse_Nominal + 1

z

TFrame_Maximum = 1.4 x (34 + 10 x (DLC + 1) + 1) x Tbit

z

TFrame_Maximum = (63 + 14 x DLC) x Tbit

Note:

The term “+1” leads to an integer result for TFrame_Max (LIN Specification 1.3).

This error is generated in Master of Slave node configuration, when the USART is transmitting and if the transmitted
value on the Tx line is different from the value sampled on the Rx line. If a bit error is detected, the transmission is
aborted at the next byte border.

This error is reported by flag LINBE in the Channel Status Register (US_CSR).

Break

Synch

Protected

Identifier

Data N

Checksum

Header

Inter-

frame

space

Response

space

Frame

Frame slot = TFrame_Maximum

Response

TXRDY

Write
US_THR

Write
US_LINID

Data 1

Data 2

Data 3

Data3

Data N-1

Data N

Frame Slot Mode

Disabled

Frame Slot Mode

Enabled

LINTC

Data 1