Microchip Technology XLP User Manual page 27

3.2.7
Two push button switches (S2 and S3) are provided for user-defined digital inputs.
They are connected to the I/O pins shown in
respective port pin to ground. Using these switches requires the corresponding pin's
internal weak pull-ups to be enabled. When the switches are not required, the pull-ups
can be disabled; this adds the ability to reduce power consumption in software.
TABLE 3-5:
Switch
3.2.8
A 100 k potentiometer (R9) is connected to AN12 for all PIC24F devices. It can be
adjusted from V
On PIC24F K-series Flash devices, the potentiometer also provides a reference volt-
age for the High-Low Voltage Detect (HLVD) module. HLVD is not implemented on
J-series Flash devices.
3.2.9
The board features one yellow and one red LED (D2 and D3) that can serve as
user-defined outputs. D2 is connected to the RB8 port pin for all PIC24F devices. D3
is connected to RB15 on K-series Flash devices only. Ensure the correct device family
is selected on switch, S4.
3.2.10
A 24AA256 256-Kbyte (32 Kbytes x 8) serial EEPROM (U6) is connected to I2C1 for
both PIC24F 20-pin and 28-pin devices. It is used to demonstrate I
It is included for nonvolatile firmware storage, in addition to the internal data EEPROM
of the PIC24F16KA102. The SDA and SCl signals for the I
user at test points near U6 and at take-off points adjacent to the prototype area.
3.2.11
The XLP 16-bit board features two different temperature sensing options. An MCP9700
analog output thermistor (U4) is connected to a PIC
The thermistor's output voltage has a linear correlation to the temperature.
The thermistor is disconnected from the microcontroller by removing jumper, JP5. To
use I/O pins efficiently, the thermistor is multiplexed with Capacitive Touch Pad 3. Avoid
contact with this pad during temperature measurements to minimize effect on
temperature measurement accuracy.
The XLP 16-bit board also implements a conventional junction diode connected to an
analog input to demonstrate low-cost temperature sensing. The Charge Time
Measurement Unit (CTMU) provides a specified current to the diode; an A/D conver-
sion determines the voltage across the diode. This voltage has a linear correlation to
the diode's temperature. For more information on this solution, refer to TB3016, "Using
the PIC
The XLP 16-bit demonstration software implements both the MCP9700 and diode CTMU
measurement solutions via a compile-time option. By default, the MCP9700 is used. Note
that when switching to the diode temperature measurement, it may be necessary to cali-
brate the measurement by changing the diode calibration constants to account for
part-to-part variation in the diode.
 2009-2015 Microchip Technology Inc.
XLP 16-Bit Development Board Hardware
User-Defined Switches
PUSH BUTTON SWITCH INPUT ASSIGNMENTS
Input Ports
28-Pin
S2 RB7/INT0
S3 RB14/CN12
Potentiometer
to V to provide an analog input voltage to the A/D Converter.
DD SS
User-Defined LEDs
Serial EEPROM
Temperature Measurement Options
®
MCU CTMU for Temperature Measurement" (DS93016) for more information.
Table 3-5. When pressed, they pull the
20-Pin
RA6/CN8 Internal weak pull-ups required
N/C
®
MCU A/D Converter input (AN1).
Note
2
C™ bus operation.
2
C bus are available to the
DS50001873C-page 27