Author: robhamerling
Date: Tue Sep 23 11:58:19 2008
New Revision: 330
Added:
trunk/unvalidated/include/peripheral/usart/serial_hw_int_cts.jal
Log:
Serial library with buffered interrupt driven I/O, and CTS flow control
Added: trunk/unvalidated/include/peripheral/usart/serial_hw_int_cts.jal
==============================================================================
--- (empty file)
+++ trunk/unvalidated/include/peripheral/usart/serial_hw_int_cts.jal Tue
Sep 23 11:58:19 2008
@@ -0,0 +1,290 @@
+-- ===================================================
+-- Title: serial_hw_int_cts.jal. Interrupt driven buffered serial
interface with flow control.
+--
+-- Author: Rob Hamerling, Copyright (c) 2008..2008, all rights reserved.
+--
+-- Adapted-by:
+--
+-- Compiler: =2.4h
+--
+-- This file is part of jallib (http://jallib.googlecode.com)
+-- Released under the BSD license
(http://www.opensource.org/licenses/bsd-license.php)
+--
+-- Description: Serial communications
+-- - receive and transmit data transfer is interrupt driven
+-- - receive and transmit data transfer uses circular buffers
+-- - automatic CTS flow control with spare free space for
FiFo buffer
+--
+-- Sources:
+--
+-- Notes:
+--
+-- The RS232 interface chip may be any converter chip.
+-- A MAX202 or similar with small or no external capacitors is preferred.
+--
+-- The PIC ports use positive logic:
+-- '1' is positive voltage, '0' is ground.
+--
+-- In the RS232 standard:
+-- - Negative voltage ('mark') means OFF for control signals, and
+-- indicates 1 (one) for data signals (start-, data-, stop-bits).
+-- - Positive voltage ('space') means ON for control signals and
+-- 0 (zero) for start-, data- and stop-bits.
+-- - Signal levels: 'mark' = -3V to -15V, 'space' = +3V to +15V
+--
+-- The MAX202 is not only a voltage level CONverter (between TTL and RS232)
+-- but also a signal INverter. You should be aware of the following:
+-- - The inversion of PIC data-in and data-out by the MAX202 is required
+-- to convert data-, start- and stop-bits to/from the corresponding
+-- RS232 polarity. So nothing special has to be done in the program
+-- because the USART of the PIC uses 'inverted' signal levels!
+-- - For CTS the inversion by the MAX202 is NOT desired.
+-- Therefore the program has to use inverted signalling for CTS:
+-- 'FALSE' is used for ON and 'TRUE' for OFF!
+-- As a reminder for this 'inverted' logic the signal is called
+-- serial_cts_inv (e.g. serial_CTS_inv = true means CTS is false!).
+--
+-- Remember also: RxD of RS232-plug connects to TX of PIC via MAX202
+-- TxD of RS232-plug connects to RX of PIC via MAX202
+--
+-- Available procedure/function for application programs:
+--
+-- - serial_setup()
+-- - serial_send_byte(byte out <byte>)
+-- - serial_receive_byte(byte in <byte>) returns bit
+--
+--
+-- =======================================================================
+
+-- Application program must specify _before_ including this library:
+
+-- const SERIAL_XMTBUFSIZE = 32 -- size of transmit buffer
+-- const SERIAL_RCVBUFSIZE = 64 -- size of receive buffer
+-- const SERIAL_DELTA = 17 -- spare receive buffer
space
+--
+-- const SERIAL_BPSRATE = 9600 -- host communications
+-- -- (range 9600..57600)
+--
+-- var bit serial_ctsinv is pin_B4 -- incoming flow ctl
+-- var bit serial_ctsinv_direction is pin_B4_direction
+
+-- Notes: - The pins above are given as example for a 16F88.
+-- - The pins for data transmit and receive are selected
automatically.
+
+-- =======================================================================
+
+-- Circular buffers for communications with PC via UART:
+
+var byte _serial_xmtbuf[SERIAL_XMTBUFSIZE] -- circular output buffer
+var byte _serial_rcvbuf[SERIAL_RCVBUFSIZE] -- circular input buffer
+
+-- Offsets in circular buffers:
+
+var byte _serial_offsetxmthead -- offset next byte from
appl
+var byte _serial_offsetxmttail -- offset next byte to
port
+var byte _serial_offsetrcvhead -- offset next byte from
port
+var byte _serial_offsetrcvtail -- offset next byte to
appl
+
+
+-- =======================================================================
+-- - UART - serial transmit interrupt handling
+-- =======================================================================
+
+procedure _serial_transmit_interrupt_handler() is
+
+ pragma interrupt
+
+ var byte x;
+
+ if ((PIR1_TXIF == TRUE) & (PIE1_TXIE == TRUE)) then -- UART xmit
interrupt
+ if (_serial_offsetxmttail != _serial_offsetxmthead) then -- data in
xmit buffer
+ x = _serial_xmtbuf[_serial_offsetxmttail] -- next
byte to xmit
+ _serial_offsetxmttail = _serial_offsetxmttail + 1 -- next
position
+ if (_serial_offsetxmttail >= SERIAL_XMTBUFSIZE) then -- beyond
buffer
+ _serial_offsetxmttail = 0 -- wrap to begin
+ end if
+ if (_serial_offsetxmttail == _serial_offsetxmthead) then -- last
byte xmt'd
+ PIE1_TXIE = FALSE -- disable xmit interrupts
+ end if
+ TXREG = x -- actually xmit byte
+ end if
+ end if
+
+end procedure
+
+
+-- =======================================================================
+-- - UART - serial receive interrupt handling
+-- =======================================================================
+
+procedure _serial_receive_interrupt_handler() is
+
+ pragma interrupt
+
+ var byte x;
+
+ if (PIR1_RCIF == TRUE) then -- UART receive interrupt
+
+ if ((RCSTA_OERR == TRUE) | (RCSTA_FERR == TRUE)) then --
frame/overr error
+ x = RCREG -- flush hardware buffer
+ while RCSTA_OERR == TRUE loop -- overrun state
+ RCSTA_CREN = FALSE -- disable UART
+ RCSTA_CREN = TRUE -- re-enable UART
+ x = RCREG -- \ flush hardware
buffers
+ x = RCREG -- /
+ end loop -- until no more overrun
+ _serial_offsetrcvtail = 0 -- \ flush circular buffer
+ _serial_offsetrcvhead = 0 -- /
+ serial_ctsinv = FALSE -- ensure CTS true
+
+ else -- data without errors
+ _serial_rcvbuf[_serial_offsetrcvhead] = RCREG -- move byte
to rcv buffer
+ x = _serial_offsetrcvhead + 1 -- update offset
+ if x >= SERIAL_RCVBUFSIZE then -- buffer overflow
+ x = 0 -- wrap
+ end if
+ if (x != _serial_offsetrcvtail) then -- buffer not yet full
+ _serial_offsetrcvhead = x -- update offset
+ end if -- (else discard byte,
+ -- CTS flow control has
failed)
+ if (serial_ctsinv == FALSE) then -- CTS is TRUE
+ if _serial_offsetrcvhead > _serial_offsetrcvtail then --
offset difference
+ x = SERIAL_RCVBUFSIZE - _serial_offsetrcvhead +
_serial_offsetrcvtail
+ else
+ x = _serial_offsetrcvtail - _serial_offsetrcvhead
+ end if
+ if (x < SERIAL_DELTA) then -- circular buffer almost
full
+ serial_ctsinv = TRUE -- set CTS FALSE
+ end if
+ end if
+ end if
+
+ end if
+
+end procedure
+
+
+-- --------------------------------------------------------------
+-- Return byte (if any) from circular receive buffer for UART
+--
+-- input: nothing
+--
+-- output: received byte (if any)
+--
+-- returns: true when byte returned
+-- false if no byte available
+--
+-- notes: - Rises CTS when receive buffer has more than <DELTA>
+-- bytes free space after delivering byte to caller.
+--
+-- -----------------------------------------------
+
+function serial_receive_byte(byte out data) return bit is
+
+ var byte x -- for buffer management
+
+ if (_serial_offsetrcvtail == _serial_offsetrcvhead) then -- receive
buffer empty
+ return false -- no data available
+ end if
+
+ data = _serial_rcvbuf[_serial_offsetrcvtail] -- first available byte
+ _serial_offsetrcvtail = _serial_offsetrcvtail + 1
+ if (_serial_offsetrcvtail >= SERIAL_RCVBUFSIZE) then -- buffer overflow
+ _serial_offsetrcvtail = 0 -- wrap
+ end if
+ if (serial_ctsinv == TRUE) then -- CTS is FALSE
+ if (_serial_offsetrcvhead > _serial_offsetrcvtail) then
+ x = SERIAL_RCVBUFSIZE - _serial_offsetrcvhead +
_serial_offsetrcvtail
+ else
+ x = _serial_offsetrcvtail - _serial_offsetrcvhead -- offset
difference
+ end if
+ if (x >= SERIAL_DELTA) then -- enough free space now
+ serial_ctsinv = FALSE -- make CTS TRUE
+ end if
+ end if
+
+ return true -- byte available
+
+end function
+
+
+-- --------------------------------------------------------------
+-- Put a single byte in circular transmit buffer for UART
+--
+-- input: byte to transmit
+--
+-- returns: transmitted byte
+--
+-- notes: - Initiates transmission (interrupt handler)
+-- when not currently transmitting
+-- - spin when transmit buffer full
+-- (wait for free buffer space)
+--
+-- -----------------------------------------------
+
+function serial_send_byte(byte in data) return byte is
+
+ var byte new_serial_offset -- offset in circular
buffer
+
+ if (_serial_offsetxmthead == _serial_offsetxmttail & -- nothing
buffered
+ PIR1_TXIF == true) then -- and UART not busy
+ PIE1_TXIE = FALSE -- disable xmt interrupt
+ TXREG = data -- transmit byte
immediately
+ else -- use circular buffer
+ _serial_xmtbuf[_serial_offsetxmthead] = data -- put byte in buffer
+ new_serial_offset = _serial_offsetxmthead + 1 -- offset next char
+ if (new_serial_offset >= SERIAL_XMTBUFSIZE) then -- beyond buffer
boundary
+ new_serial_offset = 0 -- wrap to begin
+ end if
+ while (new_serial_offset == _serial_offsetxmttail) loop -- buffer
full!
+ -- nothing -- spin until something
xmit'd
+ end loop
+ PIE1_TXIE = TRUE -- (re-)enable xmit
interrupts
+ _serial_offsetxmthead = new_serial_offset -- update offset now
+ end if
+
+ return data -- transmitted byte!
+
+end function
+
+
+-- -----------------------------------------------------------------------
+-- Serial_Setup - procedure to initialize serial communications
+-- -----------------------------------------------------------------------
+
+procedure serial_setup() is
+
+ serial_ctsinv_direction = output -- input: UART CTS->PC
+
+ _serial_offsetxmthead = 0 -- offset next byte from
appl
+ _serial_offsetxmttail = 0 -- offset next byte to port
+ _serial_offsetrcvhead = 0 -- offset next byte from
port
+ _serial_offsetrcvtail = 0 -- offset next byte to appl
+
+ RCSTA = 0b0000_0000 -- reset
+ RCSTA_SPEN = enabled -- serial port enable
+ RCSTA_CREN = enabled -- continuous receive
enable
+
+ TXSTA = 0b0000_0000 -- reset (8 bit, asyn)
+ TXSTA_TXEN = enabled -- UART transmit enabled
+ TXSTA_BRGH = true -- high baud rate
+ SPBRG = (target_clock / 16 / SERIAL_BPSRATE * 10 - 5)
/ 10
+
+ PIE1_RCIE = enabled -- UART receive int. enable
+ -- (PIE1_TXIE dynamically)
+ INTCON_PEIE = enabled -- periferal
+ INTCON_GIE = enabled -- general
+
+ serial_ctsinv = false -- CTS true: accept PC data
+
+end procedure
+
+
+-- -----------------------------------------------------------------------
+-- Initialize serial communications
+-- -----------------------------------------------------------------------
+
+serial_setup()
+
+-- =======================================================================
+
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