D E M O 9 0 8 L B 8
M A R C H 2 4 , 2 0 0 5
14
Pushbutton Switches
Two push button switches provide momentary, active low input for use in application develop-
ment. Both switches are pulled-up external to the MCU. SW1 and SW2 are enabled to the
HC08 I/O ports by the USER option bank. SW1 and SW2 provide input to HC08 I/O ports
PTB3 and PTB4 respectively.
LED Indicators
Two LED indicators provide visual output indication for use in application development. Both
LED’s are active low and will light when a logic low (0V) is driven from the respective MCU
port. Each LED is individually enabled by the USER option bank. MCU ports PTA2 and PTA3
drive LED1 and LED2 respectively.
RV1 Potentiometer
A 5k
Ω
, thumb-wheel potentiometer at RV1 provides variable resistance input for use in
application development. The device provides a 0 to VDD (+5V typical) output to the PTA1
MCU input when enabled. The POT is enabled by the USER option bank. The POT is
connected to the HC08 I/O port PT1.
RZ1 Photocell
A visible-light sensitive photocell (RZ1) is connected to the internal OP AMP/Comparator at
PTB5. PTB7/Vout and PTB6/V- provide the feedback circuit used to control the OP AMP gain.
Sensor output voltage ranges between .5V to VDD typical and is inversely proportional to
incident light intensity (VDD = Dark).
I/O CONNECTOR J1
Connector J1 is a 28-pin, surface-mount, socket header mounted on the bottom of the board.
The connector is mounted over plated-through holes in the PCB. This socket is a pass-
through type socket designed to allow header insertion from either the top or bottom. This
connector provides maximum flexibility allowing the board to connect directly to an expanded
development environment or to test equipment. Access to all MCU signals is available at con-
nector J1. The figure below details the pin-out for connector J1.
