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Initial Arduino IDE based on Processing.
This commit is contained in:
David A. Mellis
371
build/shared/lib/avrlib/uartsw.c
Executable file
371
build/shared/lib/avrlib/uartsw.c
Executable file
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/*! \file uartsw.c \brief Software Interrupt-driven UART function library. */
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//*****************************************************************************
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//
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// File Name : 'uartsw.c'
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// Title : Software Interrupt-driven UART function library
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// Author : Pascal Stang - Copyright (C) 2002-2004
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// Created : 7/20/2002
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// Revised : 4/27/2004
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// Version : 0.1
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// Target MCU : Atmel AVR Series (intended for the ATmega16 and ATmega32)
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// Editor Tabs : 4
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//
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// This code is distributed under the GNU Public License
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// which can be found at http://www.gnu.org/licenses/gpl.txt
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//
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//*****************************************************************************
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include <avr/signal.h>
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#include "global.h"
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#include "timer.h"
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#include "uartsw.h"
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// Program ROM constants
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// Global variables
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// uartsw transmit status and data variables
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static volatile u08 UartswTxBusy;
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static volatile u08 UartswTxData;
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static volatile u08 UartswTxBitNum;
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// baud rate common to transmit and receive
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static volatile u16 UartswBaudRateDiv;
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// uartsw receive status and data variables
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static volatile u08 UartswRxBusy;
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static volatile u08 UartswRxData;
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static volatile u08 UartswRxBitNum;
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// receive buffer
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static cBuffer uartswRxBuffer; ///< uartsw receive buffer
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// automatically allocate space in ram for each buffer
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static char uartswRxData[UARTSW_RX_BUFFER_SIZE];
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// functions
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//! enable and initialize the software uart
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void uartswInit(void)
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{
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// initialize the buffers
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uartswInitBuffers();
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// initialize the ports
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sbi(UARTSW_TX_DDR, UARTSW_TX_PIN);
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cbi(UARTSW_RX_DDR, UARTSW_RX_PIN);
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cbi(UARTSW_RX_PORT, UARTSW_RX_PIN);
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// initialize baud rate
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uartswSetBaudRate(9600);
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// setup the transmitter
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UartswTxBusy = FALSE;
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// disable OC1A interrupt
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cbi(TIMSK, OCIE1A);
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// attach TxBit service routine to OC1A
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timerAttach(TIMER1OUTCOMPAREA_INT, uartswTxBitService);
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// setup the receiver
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UartswRxBusy = FALSE;
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// disable OC1B interrupt
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cbi(TIMSK, OCIE1B);
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// attach RxBit service routine to OC1B
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timerAttach(TIMER1OUTCOMPAREB_INT, uartswRxBitService);
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// attach RxBit service routine to ICP
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timerAttach(TIMER1INPUTCAPTURE_INT, uartswRxBitService);
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// trigger on rising edge
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sbi(TCCR1B, ICES1);
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// enable ICP interrupt
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sbi(TIMSK, TICIE1);
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// turn on interrupts
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sei();
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}
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//! create and initialize the uart buffers
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void uartswInitBuffers(void)
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{
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// initialize the UART receive buffer
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bufferInit(&uartswRxBuffer, uartswRxData, UARTSW_RX_BUFFER_SIZE);
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}
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//! turns off software UART
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void uartswOff(void)
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{
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// disable interrupts
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cbi(TIMSK, OCIE1A);
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cbi(TIMSK, OCIE1B);
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cbi(TIMSK, TICIE1);
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// detach the service routines
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timerDetach(TIMER1OUTCOMPAREA_INT);
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timerDetach(TIMER1OUTCOMPAREB_INT);
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timerDetach(TIMER1INPUTCAPTURE_INT);
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}
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void uartswSetBaudRate(u32 baudrate)
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{
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// set timer prescaler
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timer1SetPrescaler(TIMER_CLK_DIV1);
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// calculate division factor for requested baud rate, and set it
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UartswBaudRateDiv = (u16)((F_CPU+(baudrate/2L))/(baudrate*1L));
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}
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//! returns the receive buffer structure
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cBuffer* uartswGetRxBuffer(void)
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{
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// return rx buffer pointer
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return &uartswRxBuffer;
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}
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void uartswSendByte(u08 data)
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{
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// wait until uart is ready
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while(UartswTxBusy);
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// set busy flag
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UartswTxBusy = TRUE;
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// save data
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UartswTxData = data;
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// set number of bits (+1 for stop bit)
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UartswTxBitNum = 9;
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// set the start bit
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#ifdef UARTSW_INVERT
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sbi(UARTSW_TX_PORT, UARTSW_TX_PIN);
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#else
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cbi(UARTSW_TX_PORT, UARTSW_TX_PIN);
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#endif
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// schedule the next bit
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outw(OCR1A, inw(TCNT1) + UartswBaudRateDiv);
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// enable OC1A interrupt
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sbi(TIMSK, OCIE1A);
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}
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//! gets a byte (if available) from the uart receive buffer
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u08 uartswReceiveByte(u08* rxData)
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{
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// make sure we have a receive buffer
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if(uartswRxBuffer.size)
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{
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// make sure we have data
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if(uartswRxBuffer.datalength)
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{
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// get byte from beginning of buffer
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*rxData = bufferGetFromFront(&uartswRxBuffer);
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return TRUE;
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}
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else
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{
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// no data
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return FALSE;
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}
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}
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else
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{
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// no buffer
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return FALSE;
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}
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}
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void uartswTxBitService(void)
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{
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if(UartswTxBitNum)
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{
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// there are bits still waiting to be transmitted
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if(UartswTxBitNum > 1)
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{
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// transmit data bits (inverted, LSB first)
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#ifdef UARTSW_INVERT
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if( !(UartswTxData & 0x01) )
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#else
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if( (UartswTxData & 0x01) )
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#endif
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sbi(UARTSW_TX_PORT, UARTSW_TX_PIN);
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else
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cbi(UARTSW_TX_PORT, UARTSW_TX_PIN);
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// shift bits down
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UartswTxData = UartswTxData>>1;
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}
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else
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{
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// transmit stop bit
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#ifdef UARTSW_INVERT
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cbi(UARTSW_TX_PORT, UARTSW_TX_PIN);
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#else
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sbi(UARTSW_TX_PORT, UARTSW_TX_PIN);
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#endif
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}
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// schedule the next bit
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outw(OCR1A, inw(OCR1A) + UartswBaudRateDiv);
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// count down
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UartswTxBitNum--;
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}
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else
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{
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// transmission is done
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// clear busy flag
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UartswTxBusy = FALSE;
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}
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}
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void uartswRxBitService(void)
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{
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// this function runs on either:
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// - a rising edge interrupt
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// - OC1B
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if(!UartswRxBusy)
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{
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// this is a start bit
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// disable ICP interrupt
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cbi(TIMSK, TICIE1);
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// schedule data bit sampling 1.5 bit periods from now
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outw(OCR1B, inw(TCNT1) + UartswBaudRateDiv + UartswBaudRateDiv/2);
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// clear OC1B interrupt flag
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sbi(TIFR, OCF1B);
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// enable OC1B interrupt
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sbi(TIMSK, OCIE1B);
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// set start bit flag
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UartswRxBusy = TRUE;
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// reset bit counter
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UartswRxBitNum = 0;
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// reset data
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UartswRxData = 0;
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}
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else
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{
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// start bit has already been received
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// we're in the data bits
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// shift data byte to make room for new bit
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UartswRxData = UartswRxData>>1;
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// sample the data line
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#ifdef UARTSW_INVERT
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if( !(inb(UARTSW_RX_PORTIN) & (1<<UARTSW_RX_PIN)) )
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#else
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if( !(inb(UARTSW_RX_PORTIN) & (1<<UARTSW_RX_PIN)) )
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#endif
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{
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// serial line is marking
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// record '1' bit
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UartswRxData |= 0x80;
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}
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// increment bit counter
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UartswRxBitNum++;
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// schedule next bit sample
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outw(OCR1B, inw(OCR1B) + UartswBaudRateDiv);
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// check if we have a full byte
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if(UartswRxBitNum >= 8)
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{
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// save data in receive buffer
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bufferAddToEnd(&uartswRxBuffer, UartswRxData);
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// disable OC1B interrupt
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cbi(TIMSK, OCIE1B);
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// clear ICP interrupt flag
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sbi(TIFR, ICF1);
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// enable ICP interrupt
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sbi(TIMSK, TICIE1);
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// clear start bit flag
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UartswRxBusy = FALSE;
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}
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}
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}
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/*
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void uartswRxBitService(void)
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{
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u16 thisBitTime;
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u08 bitperiods;
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u08 i;
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// bit transition was detected
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// record bit's edge time
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thisBitTime = inw(ICR1);
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cbi(PORTB, 0);
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if(!UartswRxStartBit)
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{
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// this is a start bit
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// switch to falling-edge trigger
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cbi(TCCR1B, ICES1);
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// record bit time
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UartswRxBitTime = thisBitTime;
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// set start bit flag
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UartswRxStartBit = TRUE;
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// reset bit counter
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UartswRxBitNum = 0;
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// reset data
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UartswRxData = 0;
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}
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else
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{
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// start bit has already been received
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// we're in the data bits
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// how many bit periods since last edge?
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bitperiods = (thisBitTime - UartswRxBitTime + UartswBaudRateDiv/2)/UartswBaudRateDiv;
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// set last edge time
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UartswRxBitTime = thisBitTime;
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if(bitperiods > 10)
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{
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// switch to trigger on rising edge
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sbi(TCCR1B, ICES1);
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// clear start bit flag
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UartswRxStartBit = FALSE;
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}
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else
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{
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if( inb(TCCR1B) & (1<<ICES1) )
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{
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// just triggered on a rising edge
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// previous bits were zero
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// shift in the data (data bits are inverted)
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for(i=0; i<bitperiods; i++)
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{
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UartswRxData = UartswRxData<<1;
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UartswRxData |= 0x01;
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}
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// switch to trigger on falling edge
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cbi(TCCR1B, ICES1);
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}
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else
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{
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// just triggered on a falling edge
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// previous bits were one
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// shift in the data (data bits are inverted)
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for(i=0; i<bitperiods; i++)
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{
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UartswRxData = UartswRxData<<1;
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}
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// switch to trigger on rising edge
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sbi(TCCR1B, ICES1);
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}
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// increment bit counter
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UartswRxBitNum += bitperiods;
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// check if we have a full byte + start bit
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if(bitperiods > 8)
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{
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// save data in receive buffer
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bufferAddToEnd(&uartswRxBuffer, UartswRxData);
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// switch to trigger on rising edge
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sbi(TCCR1B, ICES1);
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// clear start bit flag
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UartswRxStartBit = FALSE;
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}
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}
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}
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// turn off debug LEDs
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delay(10);
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sbi(PORTB, 0);
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sbi(PORTB, 1);
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}
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*/
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