AN2573 Freescale Semiconductor / Motorola, AN2573 Datasheet - Page 3

• Manufacturer Part Number: AN2573
• Description: LINkits LIN Evaluation Boards
• Manufacturer: Freescale Semiconductor / Motorola

Hardware
MOTOROLA
Slaves can be added or removed from the bus without powering down or
resetting the boards. When the master recognizes a new slave, it indicates this
by sweeping the LED display once from 0 to 7. It then adds this slave to its
display sequence. When it loses a slave, it shows this by sweeping the LEDs
from 7 to 0 and removing it from the display sequence.
Out of reset, each slave responds with two bytes of data using its default ID.
When in normal mode (not ID configuration mode), the push-button increments
the LEDs through a binary cycle of 1–15, skipping zero. This 4-bit number is
displayed on the slave’s LEDs and also on the top (rightmost) four bits of the
master’s LED display. It is transferred to the master using the lower four bits of
the first data byte of the slave’s response.
The simple user interface uses a single push-button switch and four LEDs, and
it allows the ID to be changed to any of the three configurable IDs (or back to
the default ID). This configuration mode is entered by holding the button down
for three seconds. In this mode, the LEDs flash and indicate the current ID. The
button then allows cycling through the four configurable IDs (first LED for ID
--xx xx01, second for --xx xx10, third for --xx xx11, and fourth for --xx xx00). If
the button is not pressed for three seconds, the mode returns to normal.
The sleep feature of the boards can be seen by switching off the master’s LIN
activity while the slaves are connected and running. After five seconds, the
boards (GR60 and EY16 only) will go to sleep as represented by all the LEDs
switching off. This feature is not supported by the QY4 slave.
The allocation of the four alternative IDs for each slave type shown in
allows as many as eight slaves of one type to be used without reallocating any
other IDs. These alternative IDs are, however, not supported by the
programmed demonstration application.
Figure 1
board. This constitutes the complete LIN node and also shows the function of
the three jumpers on the board. These jumpers are only required when using
the board to program or debug application software and should not be inserted
when running the demonstration program (a fourth jumper, J3, — only on the
QY4 slave — should be inserted when running the demonstration program).
When in the debug mode, additional hardware is required to connect the
LINkits board to the PC containing the development environment. For clarity,
these interfaces are not shown in
shows the two 20-way connectors, P1 and P2. These allow access to all of the
MCU’s pins and facilitate the addition of a “top-board” incorporating user
application hardware. Given the different resources and pin-outs of the various
Freescale Semiconductor, Inc.
For More Information On This Product,
shows the main circuit diagram of the MC68HC908EY16 LINkits slave
LINkits LIN Evaluation Boards
Go to: www.freescale.com
Figure
1. The complete circuit diagram also
Table 1
AN2573/D
Hardware
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