serial_hw2_int_cts

serial_hw2_int_cts.jal. Interrupt driven buffered serial interface with flow control.

Author Rob Hamerling, Copyright © 2008..2015, all rights reserved.
Adapted-by Karl "Kiste" Seitz
Compiler 2.4q3

Description

Serial communications for the second USART:
  - receive and transmit data transfer is interrupt driven
  - receive and transmit data transfer is buffered (circular buffers)
  - provides automatic CTS flow control with spare free space for FiFo buffer
.
This library supports:
  - Data format: 8 bits data, 1 start-bit, 1 stop bit
  - Acceptable baud rate depends on the oscillator frequency
    (see BAUD RATES tables in the datasheet).
  - Interrupt bits used: TXIE, RCIE, PEIE and GIE.
.
Available procedures/functions for application programs:
.
  - serial_hw2_init()                         -- initialise communications
.
  - serial_send2_byte(byte out )        -- send byte
                                              -- returns the transmitted byte
  - serial_hw2_read(byte out ) return bit  -- receive byte
                                              -- returns TRUE with data,
                                              -- FALSE when no data available
  - serial_hw2_write(byte in )          -- send byte (wait if queue full)
.
  - serial_hw2_data =                   -- send byte, wait if queue full
.
  - serial_hw2_tx_buffer_free()               -- get free bytes in transmit buffer
                                              -- returns number of free bytes
.
  -  = serial_hw2_data                  -- receive byte, wait if queue empty
.
Directions for use of this library in application programs (in this sequence):
.
1. Declare the following constants:
.
     const  serial_hw2_baudrate = 115200     -- line speed must be declared (no default)
.
     const bit serial2_overflow_discard = FALSE -- Transmit buffer overflow:
                                             --   FALSE: wait for free space (blocking)
                                             --   TRUE: discard data (non-blocking)
                                             -- This flag may be dynamically changed
                                             -- but must then be declared as 'var bit'
.
                                             -- Receive buffer overflow data is
                                             -- prevented by CTS flow control, provided
                                             -- the sender has flow control enabled.
                                             -- Otherwise data discarded without notification!
.
   and an alias:
.
     alias serial2_ctsinv  is  pin_B4        -- Incoming data flow control signal
                                             -- Optional, if no CTS flow control needed
                                             -- no dummy needs to be declared.
.
   And optionally you could define one or more of the constants below.
   You should do so if you want different values than shown (= defaults).
   If not defined, the following values are used:
.
     const   SERIAL2_XMTBUFSIZE  = 32        -- size of transmit buffer
     const   SERIAL2_RCVBUFSIZE  = 64        -- size of receive buffer
     const   SERIAL2_DELTA       = 17        -- spare space receive buffer
                                             -- if possible keep SERIAL2_DELTA = 17!
.
   When the physical locations of pin_TX2 and pin_RX2 are configurable for a specific
   PIC, the device file will probably contain names like pin_TX2_RC2 and pin_RX2_RC1
   and another pair with other pin suffixes.
   Depending for which pair of pins the USART is configured aliases
   without suffixes have to be specified, like:
        alias  pin_TX2            is  pin_TX2_RC2
        alias  pin_RX2            is  pin_RX2_RC1
        alias  pin_TX2_direction  is  pin_TX2_RC2_direction
        alias  pin_RX2_direction  is  pin_RX2_RC1_direction
.
2. Include this library.
.
and somewhere before actually using serial communications:
.
3. Prepare pins
      pin_B4_direction = OUTPUT              -- incoming data flow control
   Notes: - pin_TX2 and pin_RX2 are selected automatically
          - direction settings of these pins are taken care of by the library
.
4. Call serial_hw2_init() to initialize serial communications.


Notes

See serial_hw_int_cts library


Dependencies


Summary

Global variables/contants

Procedures

Private

Functions


API details

Global variables/contants

Procedures

  • serial_hw2_data'put(byte in data)

    Put byte in transmit buffer as pseudo variable
    

  • serial_hw2_init()

    Title:     Initialize second serial port
    Arguments: (none)
    Returns:   (nothing)
    
    

  • serial_hw2_write(byte in data)

    Title:     Put a single byte in transmit buffer
    Arguments: Data (byte) to transmit
    Returns    (nothing)
    Notes:     - This is a variant of serial2_send_byte() compatible with
    the procedure in the serial_hardware2 library.
     Spins when byte cannot be put in transmit buffer
    (buffer full condition).
    
    

Private

Functions

  • serial2_send_byte(byte in data) return byte

    Title:     Put a single byte in transmit buffer
    Arguments: Data (byte) to transmit
    Returns:   transmitted byte (or 0x00 when data discarded)
    Notes:     - Activates transmit interrupt handler when data buffered
     When buffer full act as indicated in 'serial2_overflow_discard'
    * TRUE:  discard data (and return 0x00 as data byte)
    * FALSE: wait for free buffer space
    (returns only after data has been stored in buffer)
    
    

  • serial_hw2_data'get() return byte

    Return next byte from receive buffer as pseudo variable
    Spin as long as no data available (buffer empty)
    

  • serial_hw2_tx_buffer_free() return byte

    Title:     Get free space in transmit buffer
    Arguments: (none)
    Returns:   Number of free bytes in transmit buffer
    Notes:     - Useful to check in advance if a string will fit in the buffer
    or if transmitting the string will block.
     Never returns zero. If "1" is returned, regard buffer as full.
    
    

  • serial_hw2_read(byte out data) return bit

    Title:     Return byte (if any) from circular receive buffer of USART
    Arguments: received byte (if any)
    Returns:   - TRUE  when byte returned
     FALSE if no byte available
    Notes:     Sets CTS high when receive buffer has more than 
    bytes free space after delivering byte to caller.
    
    


Related samples

Here are the list of samples which use this library:

16f194716f1947_serial_hw2_int_cts.jal
18f25k2218f25k22_serial_speed_converter.jal
18f631018f6310_serial_speed_converter.jal
18f672218f6722_serial_hw2_int_cts.jal