UART Communication using PIC Code

  Important :

• UART library routines require you to specify the module you want to use. To select the desired UART module, simply change the letter x in the routine prototype for a number from 1 to 2.
• Switching between the UART modules in the UART library is done by the UART_Set_Active function (UART modules have to be previously initialized).
• Number of UART modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.
  

  Library Routines

  • UARTx_Init
  • UARTx_Data_Ready
  • UARTx_Tx_Idle
  • UARTx_Read
  • UARTx_Read_Text
  • UARTx_Write
  • UARTx_Write_Text
  • UART_Set_Active

  Generic Routines

  • UART_Data_Ready
  • UART_Tx_Idle
  • UART_Read
  • UART_Read_Text
  • UART_Write
  • UART_Write_Text

  UARTx_Init

  Prototype	void UARTx_Init(const unsigned long baud_rate);
  Returns	Nothing.
  Description	Initializes desired hardware UART module with the desired baud rate. Refer to the device data sheet for baud rates allowed for specific Fosc. If you specify the unsupported baud rate, compiler will report an error.
  Requires	You need PIC MCU with hardware UART. UARTx_Init needs to be called before using other functions from UART Library. Parameters :  baud_rate: requested baud rate Refer to the device data sheet for baud rates allowed for specific Fosc.   Note : Calculation of the UART baud rate value is carried out by the compiler, as it would produce a relatively large code if performed on the library level. Therefore, compiler needs to know the value of the parameter in the compile time. That is why this parameter needs to be a constant, and not a variable.
  Example	// Initialize hardware UART1 and establish communication at 9600 bps UART1_Init(9600);

  UARTx_Data_Ready

  Prototype	char UARTx_Data_Ready();
  Returns	1 if data is ready for reading 0 if there is no data in the receive register
  Description	Use the function to test if data in receive buffer is ready for reading.
  Requires	UART HW module must be initialized and communication established before using this function.
  Example	// If data is ready, read it: if (UART1_Data_Ready() == 1) { receive = UART1_Read(); }

  UARTx_Tx_Idle

  Prototype	char UARTx_Tx_Idle();
  Returns	1 if the data has been transmitted 0 otherwise
  Description	Use the function to test if the transmit shift register is empty or not.
  Requires	UART HW module must be initialized and communication established before using this function.
  Example	// If the previous data has been shifted out, send next data: if (UART1_Tx_Idle() == 1) { UART1_Write(_data); }

  UARTx_Read

  Prototype	char UARTx_Read();
  Returns	Returns the received byte.
  Description	Function receives a byte via UART. Use the function UARTx_Data_Ready to test if data is ready first.
  Requires	UART HW module must be initialized and communication established before using this function.
  Example	// If data is ready, read it: if (UART1_Data_Ready() == 1) { receive = UART1_Read(); }

  UARTx_Read_Text

  Prototype	void UARTx_Read_Text(char *Output, char *Delimiter, char Attempts);
  Returns	Nothing.
  Description	Reads characters received via UART until the delimiter sequence is detected. The read sequence is stored in the parameter output; delimiter sequence is stored in the parameter delimiter. This is a blocking call: the delimiter sequence is expected, otherwise the procedure exits (if the delimiter is not found). Parameters :  Output: received text Delimiter: sequence of characters that identifies the end of a received string Attempts: defines number of received characters in which Delimiter sequence is expected. If Attempts is set to 255, this routine will continuously try to detect the Delimiter sequence.
  Requires	UART HW module must be initialized and communication established before using this function.
  Example	Read text until the sequence “OK” is received, and send back what’s been received:  UART1_Init(4800); // initialize UART1 module Delay_ms(100); while (1) { if (UART1_Data_Ready() == 1) { // if data is received UART1_Read_Text(output, "OK", 10); // reads text until 'OK' is found UART1_Write_Text(output); // sends back text } }

  UARTx_Write

  Prototype	void UARTx_Write(char data_);
  Returns	Nothing.
  Description	The function transmits a byte via the UART module. Parameters :  _data: data to be sent
  Requires	UART HW module must be initialized and communication established before using this function.
  Example	unsigned char _data = 0x1E; ... UART1_Write(_data);

  UARTx_Write_Text

  Prototype	void UARTx_Write_Text(char * UART_text);
  Returns	Nothing.
  Description	Sends text via UART. Text should be zero terminated. Parameters :  UART_text: text to be sent
  Requires	UART HW module must be initialized and communication established before using this function.
  Example	Read text until the sequence “OK” is received, and send back what’s been received:  UART1_Init(4800); // initialize UART1 module Delay_ms(100); while (1) { if (UART1_Data_Ready() == 1) { // if data is received UART1_Read_Text(output, "OK", 10); // reads text until 'OK' is found UART1_Write_Text(output); // sends back text } }

  UART_Set_Active

  Prototype	void UART_Set_Active(char (*read_ptr)(), void (*write_ptr)(unsigned char data_), char (*ready_ptr)(), char (*tx_idle_ptr)())
  Returns	Nothing.
  Description	Sets active UART module which will be used by the UART library routines. Parameters :  read_ptr: UARTx_Read handler write_ptr: UARTx_Write handler ready_ptr: UARTx_Data_Ready handler tx_idle_ptr: UARTx_Tx_Idle handler
  Requires	Routine is available only for MCUs with two UART modules. Used UART module must be initialized before using this routine. See UARTx_Init routine
  Example	UART1_Init(9600); // initialize UART1 module UART2_Init(9600); // initialize UART2 module RS485Master_Init(); // initialize MCU as Master UART_Set_Active(&UART1_Read, &UART1_Write, &UART1_Data_Ready, &UART1_Tx_Idle); // set UART1 active RS485Master_Send(dat,1,160); // send message through UART1 UART_Set_Active(&UART2_Read, &UART2_Write, &UART2_Data_Ready, &UART2_Tx_Idle); // set UART2 active RS485Master_Send(dat,1,160); // send through UART2

  UART_Data_Ready

  Prototype	char UART_Data_Ready();
  Returns	1 if data is ready for reading 0 if there is no data in the receive register
  Description	Use the function to test if data in receive buffer is ready for reading. This is a generic routine which uses the active UART module previously activated by the UART_Set_Active routine.
  Requires	UART HW module must be initialized and communication established before using this function.
  Example	// If data is ready, read it: if (UART_Data_Ready() == 1) { receive = UART_Read(); }

  UART_Tx_Idle

  Prototype	char UART_Tx_Idle();
  Returns	1 if the data has been transmitted 0 otherwise
  Description	Use the function to test if the transmit shift register is empty or not. This is a generic routine which uses the active UART module previously activated by the UART_Set_Active routine.
  Requires	UART HW module must be initialized and communication established before using this function.
  Example	// If the previous data has been shifted out, send next data: if (UART_Tx_Idle() == 1) { UART_Write(_data); }

  UART_Read

  Prototype	char UART_Read();
  Returns	Returns the received byte.
  Description	Function receives a byte via UART. Use the function UART_Data_Ready to test if data is ready first. This is a generic routine which uses the active UART module previously activated by the UART_Set_Active routine.
  Requires	UART HW module must be initialized and communication established before using this  function.
  Example	// If data is ready, read it: if (UART_Data_Ready() == 1) { receive = UART_Read(); }

  

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