D E M O 9 S 0 8 S F 4
J U N E 9 , 2 0 0 9
U S E R G U I D E
10
TIMING
Default timing for the DEMO9S08SF4 is provided by the MC9S08SF4 internal timing source
which is active out of RESET. Refer to the MC9S08SF4 Reference Manual for details on
configuring the timing source.
COMMUNICATIONS
The MC9S08SF4 does not support serial communications. No board support for this
functionality is provided.
USER OPTIONS
The DEMO9S08SF4 includes various input and output devices to aid application development
and debug. User I/O includes 2 momentary pushbutton switches, 1 potentiometer, 1
temperature sensor, and 1 piezo buzzer. Each device may be enabled or disabled individually
with the USER1 option header. Each user enable is clearly marked as to functionality.
Pushbutton Switches
Two push button switches provide momentary, active-low input, for user applications. Pull-ups
internal to the MCU must be enabled to provide error free operation. Pushbutton switches
SW1 and SW2 are enabled to the MCU I/O ports by the USER1 option bank. Figure 5 below
shows the user jumper settings and MCU connections.
Potentiometer
A 5k ohm, thumb-wheel type, potentiometer at RV1 provides variable resistance input for user
applications. The output is the result of a voltage divider that changes as the thumb-wheel is
turned. The potentiometer is connected between VDD and GND with the center tap providing
the divider output. Figure 5 below shows the user jumper settings and MCU connection.
Temperature Sensor
A surface-mount, NTC thermistor (B = 3900) is installed at location RZ1. This component
provides a voltage input to the MCU inversely proportional to temperature. Figure 5 below
shows the user jumper settings and MCU connections.
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