Pic16f877a Datasheet

The 7490 datasheet specifies that this counter contains four masterslave flipflops and additional gating to provide a dividebytwo counter and a threes. Measurement and control of temperature and relative humidity finds applications in numerous areas. These days devices are available which have both temperature and. KSAcxGtWG84/hqdefault.jpg' alt='Pic16f877a Datasheet' title='Pic16f877a Datasheet' />DMX512 RGB LED Wash Light Control Board A full featured driver board to control Red, Green, Blue LEDs. When paired with the correct output board, it. Introduction This little project will demonstrate how you can build NEC protocol based Infrared Remote Control to use with various NEC Protocol IR. Using UART of PIC Microcontroller with MPLAB XC8. UART stands for Universal Asynchronous Receiver Transmitter. It is a very popular serial communication interface which provides Full Duplex communication between two devices. UART uses two data lines for sending TX and receiving RX data. GroundReference of both devices should be made common. PIC16F877A. PIC16F877A PDFdatasheet. PIC16F877APIC16F877A. PDFdatasheet. As the name indicates it is an asynchronous communication interface, which means that it doesnt need to send CLOCK along with data as in synchronous communications. UART is the communication interface used by our old computers RS 2. Some of the Microchips PIC Microcontroller has built in USART Module. USART stands for Universal Synchronous Asynchronous Receiver Transmitter and it can be configured in following modes. UART Asynchronous Full DuplexUSRT Master Synchronous Half DuplexUSRT Slave Synchronous Half DuplexIn this tutorial we will learn how to use UART Mode of USART Module using MPLAB XC8 Compiler. For demonstration we are using PIC 1. F8. 77. A microcontroller. Bitstrips For Windows 8. PIC 1. 6F8. 77. A USART Module. USART Registers. TXSTA Transmit Status and Control Register. TXSTA Transmit Status and Control Register. Bit 0 TX9. D This is the 9th bit of data in the 9 bit transmission mode which is commonly used as a Parity Bit. Bit 1 TRMT  This is the Transmit Shift Register TSR status bit. This can be used to check whether the data written to transmit register is transmitted or not. When the TRS is empty this bit is set and when the TSR is full this bit will be 0. Bit 2 BRGH This is the High Baud Rate Select bit for Asynchronous mode operation and is unused in Synchronous mode. Setting this bit selects High Speed and clearing this bit selects Low Speed baud rates. You will can see the baud rate calculation later in this article. Bit 3 Unimplemented This bit is unimplemented and will read as 0. Bit 4 SYNC This is the USART Mode select bit. Setting this bit selects Synchronous mode while clearing this bit selects Asynchronous mode. Bit 5 TXEN Setting this bit enables the transmission. In the synchronous mode operation CREN and SREN bits of RCSTA register overrides this bit. Bit 6 TX9 When this bit is set it enables the 9 bit transmission otherwise 8 bit transmission is used. Bit 7 CSRC Clock Source Select Bit, this bit has no application in the Asynchronous mode operation of USART module. It is used to select master or slave mode in Synchronous mode operation. RCSTA Receive Status and Control Register. RCSTA Receive Status and Control Register. Bit 0 RX9. D This is the 9th bit of Received Data and is commonly used as Parity Bit. Bit 1 OERR Overrun Error bit. A high at this bit indicates that Overrun error has occured. Bit 2 FERR Framing Error bit. Framing Error while 0 stands for No Framing Error. Bit 3 ADDEN Address Detect Enable bit. This bit is applicable only in Asynchronous 9 bit mode. Setting this bit enables Address Detect. Bit 4 CREN Continuous Receive Enable bit. Setting this bit will enable Continuous Receive. In the Synchronous Mode CREN overrides SREN. Bit 5 SREN Single Receive Enable bit. This bit has no effect on Asynchronous mode and Synchronous Slave mode. Setting this bit will enables Single Receive. This bit will cleared after the reception is complete. Bit 6 RX9 Setting this bit enables 9 bit reception otherwise it will be in 8 bit reception mode. Bit 7 SPEN Serial Port Enable bit. Setting this bit enables serial port and configures RC7, RC6 as serial port pins. USART Baud Rate Generator BRGBaud Rate Generator provides the required clock for the data transmission and reception. USART module has a dedicated 8 bit baud rate generator which supports both Synchronous and Asynchronous modes. The 8 bit SPBRG register controls the time period of this free running timer. In Asynchronous mode BRGH, 2nd bit of TXSTA register also controls the generated baud rate but in Synchronous mode it is ignored. Baud Rate can be calculated from the following equations, where FOSC is the clock frequency of the microcontroller. PIC USART Baud Rate Formula. MPLAB XC8 Programming. Initializing UARTchar UARTInitconst long int baudrate. XTALFREQ baudrate6. SPBRG for Low Baud Rate. If High Baud Rage Required. XTALFREQ baudrate. SPBRG for High Baud Rate. BRGH 1 Setting High Baud Rate. SPBRG x Writing SPBRG Register. SYNC 0 Setting Asynchronous Mode, ie UART. SPEN 1 Enables Serial Port. TRISC7 1 As Prescribed in Datasheet. TRISC6 1 As Prescribed in Datasheet. CREN 1 Enables Continuous Reception. TXEN 1 Enables Transmission. Returns 1 to indicate Successful Completion. Returns 0 to indicate UART initialization failed. Note 6th and 7th bit of TRISC registers are set as prescribed in the datasheet. Sending Data Through UARTWriting a Charactervoid UARTWritechar data. TRMT. TXREG data. Checking Transmit Registerchar UARTTXEmpty. Writing Textvoid UARTWriteTextchar ext. UARTWritetexti. The following function can be used to write a string or array of characters to UART. It is accomplished by continuous use of character writing function UARTWrite. Receiving Data Through UARTData Received or Not. The following function can be used to check whether the data is ready to read from the Receive Register. It uses the flag bit RCIF which will be set when the data reception is completed. UARTDataReady. Reading a Character. The following function wait till the reception is complete and reads 8 bit data from the Receive Register. UARTRead. while RCIF. RCREG. Reading Text. The following function can be used to read a desired length of text or sequence of characters continuously. UARTReadTextchar utput, unsigned int length. Outputi UARTRead. For simplifying the program readability we put all the above functions to a header file uart. Thus you just need to include this header file and use required functions. For demonstrating the working of these functions we are using the following example. PIC to PIC Communication using UARTIn this example we are controlling LEDs connected to a PIC using Switches connected to another PIC Microcontroller. For the sake of explanation call these microcontrollers Slave and Master respectively. In the circuit diagram given below a DIP 8 Switch is connected to PORTB of the Master Microcontroller which is configured as Input Port. When a Switch is turned ON, the corresponding pin will be Grounded LOW. Data Read from the PORTB of Master Microcontroller is send to Slave Microcontroller using UART interface. The Slave Microcontroller writes the received data to its PORTB which is configured as Output. Thus LEDs connected to Slave Microcontroller will Glow depending upon the status of the DIP Switch connected to the Master Microcontroller. Circuit Diagram. Note 1 TX of Master Microcontroller is connected to RX of Slave Microcontroller and RX of Master Microcontroller is connected to the TX of Slave Microcontroller. Note 2 Instead of using PULL UP or PULL DOWN resistors along with switch, we are using INTERNAL PULL UP of PORTB which is enabled in the program. MPLAB XC8 Codes. Master Codedefine XTALFREQ 8. BEGIN CONFIG. pragma config FOSC HS. WDTE OFF. pragma config PWRTE OFF. BOREN ON. pragma config LVP OFF. CPD OFF. pragma config WRT OFF. CP OFF. TRISB 0x. FF PORTB as Input.