Datasheet

NACT(slave2)=PUBLISH
46.6.9.11 Response Data Length
The LIN response data length is the number of data fields (bytes) of the response excluding the checksum.
The response data length can either be configured by the user or be defined automatically by bits 4 and 5 of the
Identifier (compatibility to LIN Specification 1.1). The user can choose between these two modes using the
US_LINMR.DLM:
•
DLM = 0: The response data length is configured by the user via US_LINMR.DLC. The response data length is
equal to (DLC + 1) bytes. DLC can be programmed from 0 to 255, so the response can contain from 1 data byte
up to 256 data bytes.
• DLM = 1: The response data length is defined by the Identifier (US_LINIR.IDCHR) according to the table below.
The US_LINMR.DLC is discarded. The response can contain 2 or 4 or 8 data bytes.
Table 46-13. Response Data Length if DLM = 1
IDCHR[5] IDCHR[4] Response Data Length [Bytes]
0 0 2
0 1 2
1 0 4
1 1 8
Figure 46-43. Response Data Length
User configuration: 1–256 data fields (DLC+1)
Identifier configuration: 2/4/8 data fields
Sync
Break
Sync
Field
Identifier
Field
Checksum
Field
Data
Field
Data
Field
Data
Field
Data
Field
46.6.9.12 Checksum
The last field of a frame is the checksum. The checksum contains the inverted 8-bit sum with carry, over all data
bytes or all data bytes and the protected identifier
. Checksum calculation over the data bytes only is called classic
checksum and it is used for communication with LIN 1.3 slaves. Checksum calculation over the data bytes and the
protected identifier byte is called enhanced checksum and it is used for communication with LIN 2.0 slaves.
The USART can be configured to:
• Send/Check an Enhanced checksum automatically (CHKDIS = 0 & CHKTYP = 0)
• Send/Check a Classic checksum automatically (CHKDIS = 0 & CHKTYP = 1)
• Not send/check a checksum (CHKDIS = 1)
This configuration is made by the Checksum Type (CHKTYP) and Checksum Disable (CHKDIS) fields of US_LINMR.
If the checksum feature is disabled, the user can send it manually all the same, by considering the checksum as a
normal data byte and by adding 1 to the response data length (see Response Data Length).
46.6.9.13 Frame Slot Mode
This mode is useful only for master nodes. It complies with the following rule: each frame slot should be longer than
or equal to t
Frame_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 t
Frame_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 t
Frame_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 t
Frame_Maximum
is calculated as below:
SAM E70/S70/V70/V71 Family
Universal Synchronous Asynchronous Receiver T
ransc...
© 2019 Microchip T
echnology Inc.
Datasheet
DS60001527D-page 1212