M 5 2 2 3 3 D E M O
S E P T E M B E R 2 5 , 2 0 0 6
17
Table 7: User Option Connections
OPTION
MCU PORT
MCU PIN
SW1
IRQ4
57
SW2
IRQ7
58
LED1
DTIN0
22
LED2
DTIN1
23
LED3
DTIN2
18
LED4
DTIN3
19
RV1
AN0
25
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 switch operation. Pushbutton
switches SW1 and SW2 are connected to MCU I/O ports IRQ4* and IRQ7* respectively.
User LED’s
Four green LED’s are provided for use in application development and debug. Each LED is
configured active-high. Indicators LED1 through LED4 are enabled by the LED_EN option
header. A 3S buffer between the MCU port and the user LED’s provides the drive current
necessary to control the LED’s.
Figure 8: LED_EN Option Header
LED_EN
▪
▪
ON
User LED’s enabled active-high
LED_EN
▪
▪
OFF
User LED’s disabled
Potentiometer
A 5k ohm, single-turn, thumb-wheel type, potentiometer at RV1 provides continuous, 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. This center tap is connected to the MCU on input
AN0. The potentiometer may be disconnected from AN0 by means of the POT_EN option
header.
