User manual

PIC18 Wireless Development Board

2.1.3 PICtail Port

PICtail Port is a 28-pin interface port that supports Microchip’s RF based daughter

cards. PICtail Port provides the following interfaces to the daughter cards:

• Power supply

• SPI interface

• Interrupt request lines

2.1.4 Push Buttons

PIC18 Wireless Development board contains two push buttons, RB0 and RB2. These

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 Port B pull-ups of the microcontroller before evaluating the button state.

Example 2-1 illustrates a possible solution to evaluate the state of RB2.

EXAMPLE 2-1: CODE EXAMPLE FOR EVALUATING THE STATE OF RB2

2.1.5 Onboard Temperature Sensor

The temperature sensor used is the Microchip’s MC9700A, which is a low-power Linear

Active Thermistor™ IC. To minimize power consumption, the sensor is powered from

a port pin. After powering up, the sensor output can be measured after a minute. The

internal AD converter of the microcontroller is used to measure the temperature value.

2.1.6 Onboard Serial EEPROM

The Onboard Serial EEPROM is a low-power, Microchip’s 25LC256 256K SPI Bus

Serial EEPROM, which shares the SPI interface with the PICtail port. But Onboard

Serial EEPROM has its own active low chip select line connected to the RD5 port pin.

2.1.7 Debug LEDs

The PIC18 Wireless Development Board contains three LEDs for debug purposes. To

conserve battery power, LEDs power can be disconnected by removing the JP201 and

LED power jumper.

Note: 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 pins.

//Initialize RB2

TRISBbits.TRISB2 = 1; // RB2 is an input

ANCON1 |= 0x01; // RB2 is a digital pin

User code

//Evaluating RB2

INTCON2bits.RBPU = 0; // PortB pull ups are enabled

if (PORBbits.RB2 == 0) // RB2 is pushed

{

RB2 PB code...

}

INTCON2bits.RBPU = 1; // PortB pull ups are disabled