AN2432 Freescale Semiconductor / Motorola, AN2432 Datasheet - Page 5

• Manufacturer Part Number: AN2432
• Description: LIN Sample Application for the MC68HC908EY16 Evaluation Board
• Manufacturer: Freescale Semiconductor / Motorola

LIN evaluation board hardware
MOTOROLA
LIN Sample Application for the MC68HC908EY16 Evaluation Board
The third, and most sophisticated, development possibility is to use an MMDS
or MMEVS with an MC68HC908EY16 EM module (M68EML08EY). To use this
option, the MCU should be removed from the board and replaced with the
appropriate target header and cable to interface with the MMDS/MMEVS.
Codewarrior is also suitable for use with this hardware set-up.
The schematic of the MC68HC908EY16 LIN evaluation board is shown in
figure 1. Apart from the MCU itself, two chips are required to facilitate a simple
LIN node. These are the LIN interface, in this case the MC33399 and a 5 volt
regulator. The regulator used on the PCB is a 3-pin 7805. The board also
incorporates an RS232 serial port using an LT1181 interface chip. The port,
with a standard 9-way “D” connector, allows easy connection to the serial port
of a PC to facilitate FLASH programming and software debugging using
Metrowerks (e.g. Codewarrior) or P&E (e.g. ICS and PROG08) utilities. If the
MCU is de-soldered, there is sufficient space around its footprint to fit a target
header for the MMDS/MMEVS development system if this is preferred.
The MC33399 includes an internal 30kohm LIN pull-up so this does not need
to be fitted on the PCB if it is being used as a slave. The capability to add a
1kohm master pull-up is, however, incorporated. The LIN bus is accessible via
a 3-pin header that includes V
volt connection and the optional 1kohm pull-up are reverse polarity protected.
Although the MC68HC908EY16 has an on-chip oscillator, an 8MHz crystal is
included on the board. This can be used for applications which need the
accuracy of a crystal and also allows easier development of those which will
eventually use the on-chip oscillator. The intention is that an application can be
fully written and debugged using an accurate clock prior to modifying it to
incorporate any oscillator trimming of the internal clock that may be required.
This will always be necessary for LIN applications which use the internal
oscillator. Use of the crystal requires removal of the 9.8304MHz oscillator
module and the addition of a link at J2 and between pins 11 and 13 of the
Cyclone/Multilink connector (P4).
11. To develop new LIN applications the source code file LEDemo.c should
Freescale Semiconductor, Inc.
For More Information On This Product,
(e.g. the VCT (Volcano Communications Technologies) LINspector)
should be added.
be removed from the project and replaced with the new application
source file(s). This, and a procedure for creating a completely new
Codewarrior project, are described in detail in appendix I. Creation of a
new project allows development of a different application, with its own
LIN characteristics (message IDs etc.), without interfering with the
supplied demonstration application.
Go to: www.freescale.com
BAT
(12 volts) and ground connections. This 12
LIN evaluation board hardware
AN2432/D
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