serial_hw2_int_cts
serial_hw2_int_cts.jal. Interrupt driven buffered serial interface with flow control.
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Author
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Rob Hamerling, Copyright © 2008..2020, all rights reserved.
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Adapted-by
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Karl "Kiste" Seitz, Rob Jansen
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Compiler
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2.5r4
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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
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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.
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Available procedures/functions for application programs:
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- serial_hw2_init() -- initialise communications
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- 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)
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- serial_hw2_data = -- send byte, wait if queue full
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- serial_hw2_tx_buffer_free() -- get free bytes in transmit buffer
-- returns number of free bytes
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- = serial_hw2_data -- receive byte, wait if queue empty
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Directions for use of this library in application programs (in this sequence):
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1. Declare the following constants:
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const serial_hw2_baudrate = 115200 -- line speed must be declared (no default)
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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'
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-- Receive buffer overflow data is
-- prevented by CTS flow control, provided
-- the sender has flow control enabled.
-- Otherwise data discarded without notification!
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and an alias:
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alias serial2_ctsinv is pin_B4 -- Incoming data flow control signal
-- Optional, if no CTS flow control needed
-- no dummy needs to be declared.
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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:
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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!
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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
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2. Include this library.
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and somewhere before actually using serial communications:
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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
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4. Call serial_hw2_init() to initialize serial communications.
Notes
See serial_hw_int_cts library
Dependencies
Private
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serial_hw2_data'put(byte in data)
Put byte in transmit buffer as pseudo variable
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serial_hw2_init()
Title: Initialize second serial port
Arguments: (none)
Returns: (nothing)
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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
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serial_hw2_data_ready() return bit
generic function to check if transmit buffer is empty
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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)
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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.
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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.
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serial_hw2_data_available() return bit
generic function to check if a byte is received
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serial_hw2_data'get() return byte
Return next byte from receive buffer as pseudo variable
Spin as long as no data available (buffer empty)
Here are the list of samples which use this library: