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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
375 of 571
NXP Semiconductors
UM10316
Chapter 22: LPC29xx LIN 0/1
4.9 LIN master-controller time-out register
The LIN master-controller time-out register LTO defines the maximum number of bit times
(TO) within which a response from all the LIN slaves connected to one node should have
completed. The time-out starts as soon as the LIN header is transmitted (the value of the
time-out register is decremented with every bit-time) and a slave response is expected. If
it has been enabled, the slave-not-responding error interrupt NRI is asserted as soon as
the time-out limit is exceeded.
In an application there are two possible ways of configuring the time-out condition:
1. Configure the time-out condition only once, during the initialization phase (applicable
when all expected slave responses have the same or a similar length).
2. Configure the time-out condition prior to each LIN message (applicable when the
expected slave-response length varies).
The time-out period to be programmed can be calculated from the following formula:
where:
T
bit
is the nominal time required to transmit a bit, as defined in LIN physical layer;
N
data
is the number of data fields sent with the slave response.
shows the bit assignment of the LTO register.
Table 311. LIN master-controller checksum register bit description
* = reset value
Bit
Symbol
Access
Value
Description
31 to 8
reserved
R
-
Reserved; do not modify. Read as logic 0
7 to 0
CS
R/W
LIN message checksum. When the LIN master
controller is transmitting the checksum register
contains the hardware- or software-calculated
checksum value depending on the software
checksum bit. When the LIN master controller
is receiving the register contains the received
checksum value from the slave node
00h*
Fig 91. Time-out period for all LIN slave nodes
TO
t
response maximum
(
)
T
bit
-------------------------------------------
1.4
t
response nominal
(
)
T
bit
-----------------------------------------
×
=
=
t
response nominal
(
)
10
N
data
1
+
〈
〉
×
T
bit
×
=
001aaa220
Header
Response
data field(s) + checksum field
data field(s) + checksum field
expected message
complete time frame
minimum frame length
maximum frame length
time-out period
Slave is sending and Master is receiving