C8051F850-DK-UG Datasheet, PDF (10/36 Pages) Silicon Laboratories – UDP C8051F850 MCU CARD USER’S GUIDE FOR C8051F85X/86X MCUS

C8051F850-DK-UG
5.1. Push-Button Switches and LEDs (S1-2, DS5-6)
The UDP C8051F850 MCU Card has two push-button switches and two LEDs. The two LEDs connect to P1.0 and
P1.1, and the two switches connect to P1.7 and P2.1. The switches are normally open and pull the pin voltage to
ground when pressed. The LEDs connect to VDD through a current-limiting resistor and turn on when the
corresponding port pin is low.
The header J27 can be used to disconnect the switches and LEDs from the GPIO pins.
Table 1. Switch and LED Pin Descriptions
MCU Pin
PB1.0
PB1.1
PB1.7
PB2.1
Function
Red LED DS5 (LED1)
Red LED DS6 (LED2)
Switch S1
Switch S2
5.2. Analog Terminals (J34)
Several of the C8051F850 port pins used for analog functions are connected to the J34 terminal block. Refer to
Table 2 for the J34 terminal block connections.
Table 2. Terminal Block Pin Descriptions (J34)
Terminal Pin
1
2
3
4
5
6
MCU I/O
VREF / P0.0
GND
ADC0.9 / P1.1
ADC0.12 / P1.4
ADC0.10 / P1.2
ADC0.13 / P1.5
5.3. Potentiometer (R13)
The potentiometer is available on P1.2 (ADC0.10). To use the potentiometer, install a shorting block on J27 pins 9
and 10 to connect P1.2 to the potentiometer.
5.4. Voltage and Ground Reference (J32)
The C8051F850 has options to use an external voltage reference on the P0.0 / VREF pin and an external analog
ground reference on the P0.1 / AGND pin. The J32 header allows an external supply to clip to pin 1 for AGND and
pin 2 for VREF. These signals can then be connected to the MCU by populating a shorting block between pins 3
and 5 for AGND and pins 4 and 6 for VREF. Populating this shorting block for VREF connects P0.0 to the required
capacitors for the external reference.
MCU Pin
P0.0
P0.1
Table 3. Terminal Block Pin Descriptions (J25)
Analog Signal
VREF
AGND
Description
Clip external source to J32 pin 2, apply shorting block
between pins 4 and 6 to connect to the MCU
Clip external ground to J32 pin 1, apply shorting block
between pins 3 and 5 to connect to the MCU
10
Rev. 0.2