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| 1 | 6 | kaklik | /*! \file uartsw.c \brief Software Interrupt-driven UART function library. */ |
| 2 | //***************************************************************************** |
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| 3 | // |
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| 4 | // File Name : 'uartsw.c' |
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| 5 | // Title : Software Interrupt-driven UART function library |
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| 6 | // Author : Pascal Stang - Copyright (C) 2002-2004 |
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| 7 | // Created : 7/20/2002 |
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| 8 | // Revised : 4/27/2004 |
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| 9 | // Version : 0.1 |
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| 10 | // Target MCU : Atmel AVR Series (intended for the ATmega16 and ATmega32) |
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| 11 | // Editor Tabs : 4 |
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| 12 | // |
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| 13 | // This code is distributed under the GNU Public License |
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| 14 | // which can be found at http://www.gnu.org/licenses/gpl.txt |
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| 15 | // |
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| 16 | //***************************************************************************** |
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| 17 | |||
| 18 | #include <avr/io.h> |
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| 19 | #include <avr/interrupt.h> |
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| 20 | |||
| 21 | #include "global.h" |
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| 22 | #include "timer.h" |
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| 23 | #include "uartsw.h" |
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| 24 | |||
| 25 | // Program ROM constants |
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| 26 | |||
| 27 | // Global variables |
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| 28 | |||
| 29 | // uartsw transmit status and data variables |
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| 30 | static volatile u08 UartswTxBusy; |
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| 31 | static volatile u08 UartswTxData; |
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| 32 | static volatile u08 UartswTxBitNum; |
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| 33 | |||
| 34 | // baud rate common to transmit and receive |
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| 35 | static volatile u16 UartswBaudRateDiv; |
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| 36 | |||
| 37 | // uartsw receive status and data variables |
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| 38 | static volatile u08 UartswRxBusy; |
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| 39 | static volatile u08 UartswRxData; |
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| 40 | static volatile u08 UartswRxBitNum; |
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| 41 | // receive buffer |
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| 42 | static cBuffer uartswRxBuffer; ///< uartsw receive buffer |
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| 43 | // automatically allocate space in ram for each buffer |
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| 44 | static char uartswRxData[UARTSW_RX_BUFFER_SIZE]; |
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| 45 | |||
| 46 | // functions |
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| 47 | |||
| 48 | //! enable and initialize the software uart |
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| 49 | void uartswInit(void) |
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| 50 | { |
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| 51 | // initialize the buffers |
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| 52 | uartswInitBuffers(); |
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| 53 | // initialize the ports |
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| 54 | sbi(UARTSW_TX_DDR, UARTSW_TX_PIN); |
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| 55 | cbi(UARTSW_RX_DDR, UARTSW_RX_PIN); |
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| 56 | cbi(UARTSW_RX_PORT, UARTSW_RX_PIN); |
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| 57 | // initialize baud rate |
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| 58 | uartswSetBaudRate(9600); |
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| 59 | |||
| 60 | // setup the transmitter |
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| 61 | UartswTxBusy = FALSE; |
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| 62 | // disable OC1A interrupt |
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| 63 | cbi(TIMSK, OCIE1A); |
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| 64 | // attach TxBit service routine to OC1A |
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| 65 | timerAttach(TIMER1OUTCOMPAREA_INT, uartswTxBitService); |
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| 66 | |||
| 67 | // setup the receiver |
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| 68 | UartswRxBusy = FALSE; |
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| 69 | // disable OC1B interrupt |
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| 70 | cbi(TIMSK, OCIE1B); |
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| 71 | // attach RxBit service routine to OC1B |
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| 72 | timerAttach(TIMER1OUTCOMPAREB_INT, uartswRxBitService); |
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| 73 | // attach RxBit service routine to ICP |
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| 74 | timerAttach(TIMER1INPUTCAPTURE_INT, uartswRxBitService); |
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| 75 | // trigger on rising edge |
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| 76 | sbi(TCCR1B, ICES1); |
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| 77 | // enable ICP interrupt |
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| 78 | sbi(TIMSK, TICIE1); |
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| 79 | |||
| 80 | // turn on interrupts |
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| 81 | sei(); |
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| 82 | } |
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| 83 | |||
| 84 | //! create and initialize the uart buffers |
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| 85 | void uartswInitBuffers(void) |
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| 86 | { |
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| 87 | // initialize the UART receive buffer |
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| 88 | bufferInit(&uartswRxBuffer, uartswRxData, UARTSW_RX_BUFFER_SIZE); |
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| 89 | } |
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| 90 | |||
| 91 | //! turns off software UART |
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| 92 | void uartswOff(void) |
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| 93 | { |
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| 94 | // disable interrupts |
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| 95 | cbi(TIMSK, OCIE1A); |
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| 96 | cbi(TIMSK, OCIE1B); |
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| 97 | cbi(TIMSK, TICIE1); |
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| 98 | // detach the service routines |
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| 99 | timerDetach(TIMER1OUTCOMPAREA_INT); |
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| 100 | timerDetach(TIMER1OUTCOMPAREB_INT); |
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| 101 | timerDetach(TIMER1INPUTCAPTURE_INT); |
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| 102 | } |
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| 103 | |||
| 104 | void uartswSetBaudRate(u32 baudrate) |
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| 105 | { |
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| 106 | // set timer prescaler |
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| 107 | timer1SetPrescaler(TIMER_CLK_DIV1); |
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| 108 | // calculate division factor for requested baud rate, and set it |
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| 109 | UartswBaudRateDiv = (u16)((F_CPU+(baudrate/2L))/(baudrate*1L)); |
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| 110 | } |
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| 111 | |||
| 112 | //! returns the receive buffer structure |
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| 113 | cBuffer* uartswGetRxBuffer(void) |
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| 114 | { |
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| 115 | // return rx buffer pointer |
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| 116 | return &uartswRxBuffer; |
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| 117 | } |
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| 118 | |||
| 119 | void uartswSendByte(u08 data) |
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| 120 | { |
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| 121 | // wait until uart is ready |
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| 122 | while(UartswTxBusy); |
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| 123 | // set busy flag |
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| 124 | UartswTxBusy = TRUE; |
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| 125 | // save data |
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| 126 | UartswTxData = data; |
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| 127 | // set number of bits (+1 for stop bit) |
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| 128 | UartswTxBitNum = 9; |
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| 129 | |||
| 130 | // set the start bit |
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| 131 | sbi(UARTSW_TX_PORT, UARTSW_TX_PIN); |
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| 132 | // schedule the next bit |
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| 133 | outw(OCR1A, inw(TCNT1) + UartswBaudRateDiv); |
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| 134 | // enable OC1A interrupt |
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| 135 | sbi(TIMSK, OCIE1A); |
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| 136 | } |
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| 137 | |||
| 138 | //! gets a byte (if available) from the uart receive buffer |
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| 139 | u08 uartswReceiveByte(u08* rxData) |
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| 140 | { |
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| 141 | // make sure we have a receive buffer |
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| 142 | if(uartswRxBuffer.size) |
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| 143 | { |
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| 144 | // make sure we have data |
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| 145 | if(uartswRxBuffer.datalength) |
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| 146 | { |
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| 147 | // get byte from beginning of buffer |
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| 148 | *rxData = bufferGetFromFront(&uartswRxBuffer); |
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| 149 | return TRUE; |
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| 150 | } |
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| 151 | else |
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| 152 | { |
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| 153 | // no data |
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| 154 | return FALSE; |
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| 155 | } |
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| 156 | } |
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| 157 | else |
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| 158 | { |
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| 159 | // no buffer |
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| 160 | return FALSE; |
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| 161 | } |
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| 162 | } |
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| 163 | |||
| 164 | void uartswTxBitService(void) |
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| 165 | { |
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| 166 | if(UartswTxBitNum) |
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| 167 | { |
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| 168 | // there are bits still waiting to be transmitted |
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| 169 | if(UartswTxBitNum > 1) |
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| 170 | { |
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| 171 | // transmit data bits (inverted, LSB first) |
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| 172 | if( !(UartswTxData & 0x01) ) |
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| 173 | sbi(UARTSW_TX_PORT, UARTSW_TX_PIN); |
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| 174 | else |
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| 175 | cbi(UARTSW_TX_PORT, UARTSW_TX_PIN); |
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| 176 | // shift bits down |
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| 177 | UartswTxData = UartswTxData>>1; |
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| 178 | } |
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| 179 | else |
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| 180 | { |
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| 181 | // transmit stop bit |
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| 182 | cbi(UARTSW_TX_PORT, UARTSW_TX_PIN); |
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| 183 | } |
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| 184 | // schedule the next bit |
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| 185 | outw(OCR1A, inw(OCR1A) + UartswBaudRateDiv); |
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| 186 | // count down |
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| 187 | UartswTxBitNum--; |
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| 188 | } |
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| 189 | else |
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| 190 | { |
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| 191 | // transmission is done |
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| 192 | // clear busy flag |
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| 193 | UartswTxBusy = FALSE; |
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| 194 | } |
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| 195 | } |
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| 196 | |||
| 197 | void uartswRxBitService(void) |
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| 198 | { |
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| 199 | // this function runs on either: |
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| 200 | // - a rising edge interrupt |
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| 201 | // - OC1B |
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| 202 | if(!UartswRxBusy) |
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| 203 | { |
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| 204 | // this is a start bit |
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| 205 | // disable ICP interrupt |
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| 206 | cbi(TIMSK, TICIE1); |
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| 207 | // schedule data bit sampling 1.5 bit periods from now |
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| 208 | outw(OCR1B, inw(TCNT1) + UartswBaudRateDiv + UartswBaudRateDiv/2); |
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| 209 | // clear OC1B interrupt flag |
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| 210 | sbi(TIFR, OCF1B); |
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| 211 | // enable OC1B interrupt |
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| 212 | sbi(TIMSK, OCIE1B); |
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| 213 | // set start bit flag |
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| 214 | UartswRxBusy = TRUE; |
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| 215 | // reset bit counter |
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| 216 | UartswRxBitNum = 0; |
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| 217 | // reset data |
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| 218 | UartswRxData = 0; |
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| 219 | } |
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| 220 | else |
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| 221 | { |
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| 222 | // start bit has already been received |
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| 223 | // we're in the data bits |
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| 224 | |||
| 225 | // shift data byte to make room for new bit |
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| 226 | UartswRxData = UartswRxData>>1; |
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| 227 | |||
| 228 | // sample the data line |
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| 229 | if( !(inb(UARTSW_RX_PORTIN) & (1<<UARTSW_RX_PIN)) ) |
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| 230 | { |
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| 231 | // serial line is low |
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| 232 | // record '1' bit (data inverted) |
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| 233 | UartswRxData |= 0x80; |
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| 234 | } |
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| 235 | |||
| 236 | // increment bit counter |
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| 237 | UartswRxBitNum++; |
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| 238 | // schedule next bit sample |
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| 239 | outw(OCR1B, inw(OCR1B) + UartswBaudRateDiv); |
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| 240 | |||
| 241 | // check if we have a full byte |
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| 242 | if(UartswRxBitNum >= 8) |
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| 243 | { |
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| 244 | // save data in receive buffer |
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| 245 | bufferAddToEnd(&uartswRxBuffer, UartswRxData); |
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| 246 | // disable OC1B interrupt |
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| 247 | cbi(TIMSK, OCIE1B); |
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| 248 | // clear ICP interrupt flag |
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| 249 | sbi(TIFR, ICF1); |
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| 250 | // enable ICP interrupt |
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| 251 | sbi(TIMSK, TICIE1); |
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| 252 | // clear start bit flag |
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| 253 | UartswRxBusy = FALSE; |
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| 254 | } |
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| 255 | } |
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| 256 | } |
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| 257 | |||
| 258 | /* |
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| 259 | void uartswRxBitService(void) |
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| 260 | { |
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| 261 | u16 thisBitTime; |
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| 262 | u08 bitperiods; |
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| 263 | u08 i; |
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| 264 | |||
| 265 | // bit transition was detected |
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| 266 | // record bit's edge time |
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| 267 | thisBitTime = inw(ICR1); |
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| 268 | |||
| 269 | cbi(PORTB, 0); |
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| 270 | |||
| 271 | if(!UartswRxStartBit) |
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| 272 | { |
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| 273 | // this is a start bit |
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| 274 | // switch to falling-edge trigger |
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| 275 | cbi(TCCR1B, ICES1); |
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| 276 | // record bit time |
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| 277 | UartswRxBitTime = thisBitTime; |
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| 278 | // set start bit flag |
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| 279 | UartswRxStartBit = TRUE; |
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| 280 | // reset bit counter |
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| 281 | UartswRxBitNum = 0; |
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| 282 | // reset data |
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| 283 | UartswRxData = 0; |
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| 284 | } |
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| 285 | else |
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| 286 | { |
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| 287 | // start bit has already been received |
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| 288 | // we're in the data bits |
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| 289 | |||
| 290 | // how many bit periods since last edge? |
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| 291 | bitperiods = (thisBitTime - UartswRxBitTime + UartswBaudRateDiv/2)/UartswBaudRateDiv; |
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| 292 | // set last edge time |
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| 293 | UartswRxBitTime = thisBitTime; |
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| 294 | |||
| 295 | if(bitperiods > 10) |
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| 296 | { |
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| 297 | // switch to trigger on rising edge |
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| 298 | sbi(TCCR1B, ICES1); |
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| 299 | // clear start bit flag |
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| 300 | UartswRxStartBit = FALSE; |
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| 301 | } |
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| 302 | else |
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| 303 | { |
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| 304 | |||
| 305 | |||
| 306 | if( inb(TCCR1B) & (1<<ICES1) ) |
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| 307 | { |
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| 308 | // just triggered on a rising edge |
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| 309 | // previous bits were zero |
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| 310 | // shift in the data (data bits are inverted) |
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| 311 | for(i=0; i<bitperiods; i++) |
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| 312 | { |
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| 313 | UartswRxData = UartswRxData<<1; |
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| 314 | UartswRxData |= 0x01; |
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| 315 | } |
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| 316 | // switch to trigger on falling edge |
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| 317 | cbi(TCCR1B, ICES1); |
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| 318 | } |
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| 319 | else |
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| 320 | { |
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| 321 | // just triggered on a falling edge |
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| 322 | // previous bits were one |
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| 323 | // shift in the data (data bits are inverted) |
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| 324 | for(i=0; i<bitperiods; i++) |
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| 325 | { |
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| 326 | UartswRxData = UartswRxData<<1; |
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| 327 | } |
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| 328 | // switch to trigger on rising edge |
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| 329 | sbi(TCCR1B, ICES1); |
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| 330 | } |
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| 331 | |||
| 332 | // increment bit counter |
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| 333 | UartswRxBitNum += bitperiods; |
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| 334 | |||
| 335 | // check if we have a full byte + start bit |
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| 336 | if(bitperiods > 8) |
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| 337 | { |
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| 338 | // save data in receive buffer |
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| 339 | bufferAddToEnd(&uartswRxBuffer, UartswRxData); |
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| 340 | // switch to trigger on rising edge |
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| 341 | sbi(TCCR1B, ICES1); |
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| 342 | // clear start bit flag |
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| 343 | UartswRxStartBit = FALSE; |
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| 344 | } |
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| 345 | } |
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| 346 | } |
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| 347 | |||
| 348 | // turn off debug LEDs |
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| 349 | delay(10); |
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| 350 | sbi(PORTB, 0); |
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| 351 | sbi(PORTB, 1); |
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| 352 | } |
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| 353 | */ |
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