C 8 0 5 1 F 9 7 0 D K - U G
10
Rev. 0.1
5.2. Potentiometer (R12)
The potentiometer is available on P5.0. To use the potentiometer, install a shorting block on JP5 to connect P5.0 to
the potentiometer.
The potentiometer is referenced to P0.0, which is the voltage reference pin. Since the voltage reference can only
source ~250 µA, the simplest way to use the potentiometer is to turn on the P0.0 driver and set it to a logic high
using the port registers. The most accurate way to use the potentiometer is to externally connect P0.0 to VDD.
5.3. Capacitive Sense Buttons (CS20-27, CS30-37, CS40-47)
The capacitive sensing buttons demonstrate the C8051F970 Capacitive Sense module for use with buttons and
sliders. More information on the capacitive sense library can be found in 2.3. "Capacitive Sense‚" on page 2.
5.4. Power (SW1, J1, and J2)
The VDD power supply has three power options: on-board +3.3 V or +1.8 V regulator power, battery power, or off.
The
VDD Select
switch (SW1) is used to select between the two options.
The +3.3 V or +1.8 V regulator power option is the upper
VREG
position and allows the board to be powered from
a diode-OR of three power sources: 9 V Power Adapter (P1), the USB connector (J9), or the USB Debug Adapter
(H8). Once the
VDD Select
switch is in the
VREG
position, the VREG Select header (J1) selects b3.3 V
or +1.8 V.
The middle
VBATT
option allows the board to be powered from either two AAA batteries (BH1) or a CR2032 coin
cell (BH2). When the
VDD Select
switch is in the
VBATT
position, J2 selects between a CR2032 or two AAA
batteries
The bottom
OFF
option disconnects the board power.
5.5. Power LED (D6)
The blue power LED provides visual feedback when the board is powered through USB, the 9 V power adapter, or
the USB Debug Adapter. This LED is not tied to the battery power net to conserve energy. The power LED
indicates that power is available on the board and the VDD Power Select switch must be configured properly to
power the MCU.
5.6. Power Measurement Jumper (JP3)
The power measurement jumper (JP3) allows for easy access to measure the VDD current of the MCU. The
shorting block for this header is populated by default. The side labeled VMCU is the side isolated to the
C8051F970 MCU. To measure the supply current, remove the corresponding shorting block and connect a current
measurement device across the unpopulated header.
The voltage supply prior to the jumper is the VDD net, which supplies all of the external LEDs, switches, USB
COM, and reset pull-up. The VDD_MCU net after the jumper
only connects to the MCU.
5.7. Debug Header (H8)
The shrouded 10-pin debug header supports the Silicon Labs USB Debug Adapter. This connector provides a C2
debug connection to the C8051F970 on the target board.
5.8. Reset Button (S3)
The reset push-button switch is to the right of the debug header (H8). Pushing this button will always reset the
MCU. Note that pushing this button while the IDE is connected to the MCU will result in the IDE disconnecting from
the target.
5.9. LED Supply (JP4)
The LED supply separates the LED power from the rest of the board. Disabling the LEDs removes their power
consumption without having to modify firmware.
Not
Recommended
for
New
Designs
