Wireless Presentation

Application

Features

• Establish link between measurement unit and data collection unit

• Transmit RPM speed, measurement data

Hardware Operations

Universal Asynchronous Receiver/Transmitter (UART)

• Transmit data in 8 bits, Low start bit, High stop bit, High Idle

Internal XBee data flow diagram

• Flow control with CTS pin (high to stop when buffer less than 34 bytes of memory)

• Possible to eliminate flow control to simplified programming scheme

XBee configuration

• X-CTU program

• Modem configuration

XBee #1		XBee #1
Channel	13	Channel	13
PAN ID	8788	PAN ID	8788
DH	0	DH	0
DL	10	DL	11
MY	11	MY	10
Baud (BD)	9600	Baud (BD)	9600

Implementation

PIC24 configuration

UART baud rate with BRGH = 0 (16 clock per bit period)

UART baud rate with BRGH = 1 (4 clock per bit period)

Both equation based on F_CY = F_OSC/2; Doze mode and PLL are disabled. 

PIC24 clock diagram

External Oscillator

• Baud rate requires steady oscillating frequency

• Stabilize clock frequency

• Invariant due to temperature 

• Compose of resistor and capacitor

•  The frequency is calculated by 1/T, where T is the time constant is given by multiplying the resistance and capacitance together. 

 External Clock (EC mode)






External Oscillator (LP, XT or HS)

Ceramic Resonators









UART Operation

Arduino Connections

 

• Serial communication interface

• Arduino can direct translate the message using input/output ports

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