Datasheet

www.tektronix.com/oscilloscopes 25
Debugging Serial Buses in Embedded System Designs
Header Components:
Break Field – the break field is used to signal the beginning
of a new frame. It activates and instructs all slave devices to
listen to the remainder of the header.
Sync Field – the sync field is used by the slave devices to
determine the baud rate being used by the master node
and synchronize themselves accordingly.
Identifier Field – the identifier specifies which slave device is
to take action.
Response Components:
Data – the specified slave device responds with one to eight
bytes of data.
Checksum – computed field used to detect errors in data
transmission. The LIN standard has evolved through several
versions that have used two different forms of checksums.
Classic checksums are calculated only over the data bytes
and are used in version 1.x LIN systems. Enhanced check-
sums are calculated over the data bytes and the identifier
field and are used in version 2.x LIN systems.
Working with LIN
LIN support on Tektronix oscilloscopes is also available via
several different serial triggering and analysis options (see
Appendix A). Using the front panel Bus buttons we can define
a LIN bus by simply entering the basic parameters of the
bus such as the LIN version being used, the bit rate, polarity,
threshold, and where to sample the data (as a percent of bit
time). The LIN setup menu along with a decoded LIN frame is
shown in Figure 34.
Figure 34. LIN bus setup menu and decoded frame.