Demo Board Hardware
©
2008 Microchip Technology Inc.
DS51748A-page 21
The microcontroller uses its on-chip USB engine and transceiver to communicate the
PC side interface application, using the USB mini-B receptacle. The demo board also
uses the USB receptacle for application power as a bus-powered device.
Microcontroller and LED power is provided from the V
BUS
by Q1, an MCP1702 voltage
regulator. Provisions on the board allow for users to add components and create an
externally powered application.
For users interested in using the Touch Sense 2 Demo Board as an experimental
platform, the microcontroller can be reprogrammed through a standard interface. A
six-pin header is provided for connecting the demo board to any MPLAB ICD 2
compatible programmer. Since the ICD interface shares some input lines with the
numeric keypad interface, a separate switch (S13, not shown in the figure) allows users
to connect or disconnect the ICD lines from the scan lines. While this is not strictly
necessary, it does help to reduce the overall capacitance of the touch pads.
4.2
BOARD COMPONENTS
Figure 4-3 identifies the key hardware components for the demo board. Note that the
active components are mounted to the bottom side of the board; only the touch sensors
are on the front side.
FIGURE 4-3:
TOUCH SENSE 2 DEMO BOARD COMPONENT LAYOUT (BOTTOM SIDE)
TABLE 4-1:
BOARD COMPONENTS
Ref
Component
1
PIC24FJ256GB110 Microcontroller (U1)
2
USB mini-B Receptacle (J3)
3
ICSP™ Programming Header (J1)
4
Power Supply (D18, Q1)
5
Piezo Speaker (BZ1)
6
Directional Touch Sensor LEDs (D19-24, D26-27, D38)
7
Directional Touch Sensor Area – Front of Board (ROT1)
8
Numeric Keypad Area – Sensors on Front of Board (S1-12, S21-28, D1-10, D28-37)
9
Touch Slider Area – Sensor on Front of Board (S14, D12-17, D39-64)
10
Power Touch Switch – Sensor on Front of Board (S20, D65)
1
2
4
5
6
8
9
3
7
10
