Embedded Security Development Board
5.2.4
PICtail Port
The PICtail port is a 28-pin interface port that supports Microchip’s RF-based daughter
cards. The PICtail port provides the following interfaces to the daughter cards:
• Power Supply
• SPI interface
• Interrupt request lines
• Other digital/analog I/O lines
Note: The user must be careful about the PICtail port pins that share different
functions of the board. The user needs to check the schematics before
assigning functions for any port pin.
There are many Microchip accessory daughter cards, which have PICtail port
connectivity. When not used as one of the components in the Wireless Security Remote
Control Development Kit, the Embedded Security Development Board can be
connected with any daughter board with PICtail port, and perform different
functionalities. Refer to the Microchip web site http://www.microchip.com for accessory
daughter boards with PICtail port.
5.2.5
LCD Display
The Embedded Security Development Board supports 16x2 character LCD display with
backlight. The LCD is controlled by the host microcontroller through the SPI port. For
details about the LCD display, refer to the data sheet of NHD-C0216CZ-FSW-FBW-3V3
by Newhaven Display (http://www.newhavendisplay.com).
5.2.6
Real-Time Clock and Calendar (RTCC) Module
The Embedded Security Development Board RTCC module can be used to set and
track clock and calendar precisely. The RTCC functionality is achieved with the
Microchip MCP795W10. The RTCC module is controlled by the host microcontroller
through the SPI interface. The RTCC module can be powered either by the 3.3V power
from the Embedded Security Development Board, or by a separate coin battery when
external power is not available. For details on operating this RTCC module, refer to the
data sheet of the MCP795W10 at http://www.microchip.com/MCP795W10.
5.2.7
Push Buttons
The Embedded Security Development Board has two sets of push buttons. Each set
consists of four individual push buttons and serves as input to the host and target
application microcontrollers.
The four push buttons for the target application microcontroller are read as a single
analog input. Depending on the different ratios of pull-up and pull-down resister values,
the input analog voltages to the master microcontroller are different. Therefore, through
the ADC on the target application microcontroller, the button that is pressed can be
identified. Such design is used to save I/O pin requirement for the target application
microcontroller. The details of the push buttons design can be found in the schematics
in Appendix C.
The four push buttons for the host microcontroller are four separate digital inputs to the
slave microcontroller, due to the abundant I/O pin availability for the slave
microcontroller. All buttons are assigned to the individual interrupt lines of the
microcontroller and are not driven by external pull-up circuitry to save power
consumption. The user software must enable the PORTB pull-ups of the
microcontroller before evaluating the button state.
2012 Microchip Technology Inc.
DS41646A-page 29
MICROCHIP [ MICROCHIP ]
