elct706 microlab session #4 uart usage for bluetooth ...eee.guc.edu.eg/courses/electronics/elct706...

ELCT706 MicroLabSession #4

UART Usage for Bluetooth connection PC - PIC

ELCT 706 Session #4Dr. Mohamed Abdel GhanyEng. Salma HeshamEng. Ahmed Atteya

USART in PIC16F877A

Universal Synchronous/Asynchronous Receiver Transmitter- Can receive and transmit- Can be synchronous or Asynchronous

Synchronous:- Uses a clock and one data signal

Asynchronous:- One pin for transmission and another for reception - Full duplex asynchronous operation (both transmission and reception can occur at the same time)


USART in PIC16F877A

Universal Synchronous/Asynchronous Receiver Transmitter- Can receive and transmit- Can be synchronous or Asynchronous

Synchronous:- Uses a clock and one data signal

Asynchronous:- One pin for transmission and another for reception - Full duplex asynchronous operation (both transmission and reception can occur at the same time)

Most commonly used


UART in PIC16F877A

PIC16F877A has 4 Specific Function 8-bit Registers for USART module: 1. TXSTA2. RCSTA 3. SPBRG4. TXREG

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

TXSTA CSRC TX9 TXEN SYNC - BRGH TRMT TX9D

RCSTA SPEN RX9 SREN CREN - FERR OERR RX9D

SPBRG Baud Rate Generator Register

TXREG USART Transmitter Register


UART Library in MikroC-ProProvides comfortable work with the Asynchronous mode

Library Functions: UART1_Init UART1_Data_Ready UART1_Tx_Idle UART1_Read UART1_Read_Text UART1_Write UART1_Write_Text UART_Set_Active

Built-in UART functions which set the proper bits for the specific UART PIC registers at each required command


UART Library in MikroC-Pro


Library Functions: void UART1_Init(unsigned long baud_rate);

- It Initializes the desired UART module with the given baud rate.For PIC16F877A with 4MHz oscillator, use baud rate = 9600.

-It returns nothing

- Example: UART1_Init(2400);


Library Functions: char UART1_Data_Ready();

- It tests if there is a ready data in receive register for reading. The baud rate of the UART module must be initialized before using this function

- It returns: 1 if data is ready for reading0 if there is no data in the receive register

- Example: if(UART1_Data_Ready()){// do what ever}



Library Functions: char UART1_Tx_Idle();

- It tests if the transmit shift register is empty or not. The baud rate of the UART module must be initialized before using this function

- It returns: 1 if data is ready for reading0 if there is no data in the receive register

- Example: if(UART1_Tx_Idle()){// do what ever}



Library Functions: char UART1_Read();

- It receives one byte through the UART when data is ready in the received register. The baud rate of the UART module must beinitialized before using this function

- It returns the received byte.

- Example: x = UART1_Read(); // x is a char



Library Functions: void UART1_Read_Text(char *Output, char * Delimiter, char Attempts);

- It reads characters via UART until the delimiter sequence is detected. The parameters of this function are:output: contains the received text of successive charactersdelimiter: sequence of characters which defines the end of

the received string.Attempts: defines the number of characters in which the delimiter is expected to be found, otherwise, the procedure will exit anyway.-Example: UART1_Read_Text(output,“OK”,10);

//output is defined previously as char *output;



Library Functions: void UART1_write(char x);

- It transmits one byte through the UART module. The parameter x is the byte to be sent. The baud rate of the UART module must be initialized before using this function.

- It returns nothing.

- Example: char x = 0xFF;UART1_Write(x);



Library Functions: void UART1_Write_Text(char *text);

- It sends text via UART. The parameter text is the text to be sent. The Baud rate of the UART module should be initialized beforeusing this function.

- Example: UART1_Write(“Start”);


Control LEDs from PC/ mobile-phone using the UART module

Task 1Write the MikroC code to use the UART module to control 8 LEDs on Port B through PC/mobilephoneBluetooth such that if: -received data = “Blink” LEDs blink 3 times together with 1 second delay-Received data = “Shift”LEDs get turned ON one after the other- Received data = “ON” LEDs are turned ON- Any other received data LEDs are turned OFF


Easy Bluetooth Connection


Guiding Steps for Using UART Module with Bluetooth Connection

1. Write the MikroC code to control the LEDs on Port B according to the received string Via the UART module. Start by initializing the Baud Rate and wait for 100ms to intialize Send a test text from Bluetooth to PC/Mobile-phone, followed by new line

(0x0A) and a carriage return (0x0D) to reset the cursor position to the start of a new line. Start your while(1) where you check if data ready, then read it and control

the PORTB LEDs based on the received text.

2. Power up your Bluetooth module.3. Pair your Bluetooth module with your PC/ Mobile-phone.4. Open the X-CTU/Bluetooth terminal on PC/Mobile-phone.5. Burn the MikroC program on your PIC and plug it in the circuit.6. Send and receive through the terminal and the LEDs should be

controlled through the received strings.




Test text sent from Bluetooth module to PC based on the

MikroC code

elct706 microlab session #4 uart usage for bluetooth ...eee.guc.edu.eg/courses/electronics/elct706...

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