DEMO908QB8 MARCH 18, 2005
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LED Indicators
Indicators LED1 and LED2 are enabled from HC08 I/O ports by the USER option bank. Each
LED is active low and illuminating when a logic low signal is driven from the respective MCU
I/O port. MCU ports PTB6 and PTB7 drive LED1 and LED2 respectively. The table below
details the user jumper settings.
Potentiometer
A 5k Ω, 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. This device is connected to the MCU on signal PTA0. The table below details the user
jumper settings.
The potentiometer is not available while in monitor mode. Using the potentiometer requires
disabling the MON08 COM signal. This requires removing USB-MON08 Enable jumper ‘D’.
Otherwise results may be unpredictable.
NOTE: User-5 option jumper must be removed to enter monitor mode.
NOTE: USB-MON08 ENABLE-D jumper must be removed to use this function.
Photocell
A photoconductive photocell provides light sensitive, variable resistance input for user applica-
tions. Device resistance is inversely proportional to light intensity incident on the surface of the
device. A rail-to-rail OP amp at U2 boosts the photocell output to useable levels. This signal
is available to the MCU on signal PTA1. The table below details the user jumper settings.
NOTE: User-6 option jumper must be removed to enter monitor mode. The jumper may be
reinstalled after RESET.
Table 5: User Option Jumper Settings
Jumper On Off MCU PORT
User-1 Enable SW1 Disable SW1 PTA5 (U1-4)
User-2 Enable SW2 Disable SW2 PTA4 (U1-5)
User-3 Enable LED1 Disable LED1 PTB6 (U1-3)
User-4 Enable LED2 Disable LED2 PTB7 (U1-2)
User-5 Enable RV1 Disable RV1 PTA0 (U1-13)
User-6 Enable RZ1 Disable RZ1 PTA1 (U1-12)
NOTE: USER-5 and USER-6 must be disabled to enter Monitor mode
