D E M O 9 S 1 2 X D T 5 1 2
J U L Y 1 8 , 2 0 0 8
16
POT
A single-turn, 3/8 inch, 5K ohm trimmer potentiometer (POT) has been provided as user, ana-
log input. The part is decoupled to minimize noise during adjustment. The POT connects to
analog input PAD05/AN05 on the MCU. The figure below shows the USER enable position
and associated signal for the potentiometer.
LIGHT SENSOR
A 4mm photocell light sensor exhibiting 23K – 33K ohms of output resistance has been pro-
vided. Output resistance is inversely related to incident light intensity. A gain stage (U5) am-
plifies the sensor output before connecting to the MCU. The SENSOR connects to analog in-
put PAD04/AN04 on the MCU. The figure below shows the USER enable position and associ-
ated signal for the Light Sensor
User Signals
The following table shows the connections for each user I/O device.
Table 6: User I/O
USER
Ref Des
Signal
Device
1
SW1
PP0/KWP0/PWM0/MISO1
Push Button Switch
2
SW2
PP1/KWP1/PWM1/MOSI1
Push Button Switch
3
SW3-1
PB0
4-pos DIP Switch
4
SW3-2
PB1
4-pos DIP Switch
5
SW3-3
PB2
4-pos DIP Switch
6
SW3-4
PB3
4-pos DIP Switch
7
LED1
PB4
Green LED
8
LED2
PB5
Green LED
9
LED3
PB6
Green LED
10
LED4
PB7
Green LED
11
RV1
PAD05/AN05
Potentiometer
12
RZ1
PAD04/AN04
Light Sensor
USER ENABLE
The User option header block enables or disables each User I/O device individually. User I/O
includes 4 green LEDs, 2 push button switches, one 4-position DIP switch, a Light Sensor, and
a potentiometer. Installing a shunt enables the associated option. Removing a shunt disables
the associated option. The table below shows the configuration option for each USER I/O.
