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/****************************************************************************
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 *   Copyright (C) 2011 by Claas Anders "CaScAdE" Rathje                    *
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 *   admiralcascade@gmail.com                                               *
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 *   Project-URL: http://www.mylifesucks.de/oss/c-epilepsy/                 *
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 *                                                                          *
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 *   This program is free software; you can redistribute it and/or modify   *
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 *   it under the terms of the GNU General Public License as published by   *
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 *   the Free Software Foundation; either version 2 of the License.         *
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 *                                                                          *
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 *   This program is distributed in the hope that it will be useful,        *
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 *   but WITHOUT ANY WARRANTY; without even the implied warranty of         *
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 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          *
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 *   GNU General Public License for more details.                           *
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 *                                                                          *
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 *   You should have received a copy of the GNU General Public License      *
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 *   along with this program; if not, write to the                          *
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 *   Free Software Foundation, Inc.,                                        *
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 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.              *
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 ****************************************************************************/
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#include "usart0.h"
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volatile uint8_t rxd_buffer_locked = 0;
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volatile uint8_t rxd_buffer[RXD_BUFFER_LEN];
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volatile uint8_t txd_buffer[TXD_BUFFER_LEN];
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volatile uint8_t ReceivedBytes = 0;
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volatile uint8_t *pRxData = 0;
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volatile uint8_t RxDataLen = 0;
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/**
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 * init usart0
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 */
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void usart0_init() {
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    UBRR0H = ((F_CPU / (16UL * USART0_BAUD)) - 1) >> 8;
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    UBRR0L = (F_CPU / (16UL * USART0_BAUD)) - 1;
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    // Enable receiver and transmitter; enable RX interrupt
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    UCSR0B = (1 << RXEN0) | (1 << TXEN0) | (1 << RXCIE0);
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    // set asynchronous mode
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    UCSR0C &= ~(1 << UMSEL01);
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    UCSR0C &= ~(1 << UMSEL00);
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    // no parity
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    UCSR0C &= ~(1 << UPM01);
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    UCSR0C &= ~(1 << UPM00);
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    // 1 stop bit
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    UCSR0C &= ~(1 << USBS0);
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    // 8-bit
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    UCSR0B &= ~(1 << UCSZ02);
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    UCSR0C |= (1 << UCSZ01);
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    UCSR0C |= (1 << UCSZ00);
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    // set direction of RXD0 and TXD0 pins
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    // set RXD0 (PD0) as an input pin
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    PORTD &= ~(1 << PORTD0);
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    DDRD &= ~(1 << DDD0);
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    // set TXD0 (PD1) as an output pin
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    //PORTD |= (1 << PORTD1);
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    //DDRD &= ~(1 << DDD1);
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}
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/**
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 * disable the txd pin of usart0
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 */
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void usart0_DisableTXD(void) {
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    UCSR0B &= ~(1 << TXCIE0); // disable TX-Interrupt
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    UCSR0B &= ~(1 << TXEN0); // disable TX in USART
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    DDRD &= ~(1 << DDD1); // set TXD pin as input
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    PORTD &= ~(1 << PORTD1); // disable pullup on TXD pin
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}
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/**
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 * enable the txd pin of usart0
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 */
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void usart0_EnableTXD(void) {
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    DDRD |= (1 << DDD1); // set TXD pin as output
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    PORTD &= ~(1 << PORTD1); // disable pullup on TXD pin
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    UCSR0B |= (1 << TXEN0); // enable TX in USART
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    UCSR0B |= (1 << TXCIE0); // enable TX-Interrupt
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}
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/**
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 * send a single <character> through usart0
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 */
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void usart0_putc(unsigned char character) {
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    // wait until UDR ready
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    while (!(UCSR0A & (1 << UDRE0)));
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    UDR0 = character;
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}
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/**
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 * send a <string> throught usart0
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 */
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void usart0_puts(char *s) {
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    while (*s) {
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        usart0_putc(*s);
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        s++;
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    }
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}
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/**
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 * send a PGM<string> throught usart0
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 */
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void usart0_puts_pgm(const char* string) {
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    while (pgm_read_byte(string) != 0x00)
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        usart0_putc(pgm_read_byte(string++));
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}
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/**
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 * transmit interrupt handler
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 * unused
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 */
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ISR(USART0_TX_vect, ISR_BLOCK) {
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}
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/*
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 * receive data through usart0
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 * portions taken and adapted from
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 * http://svn.mikrokopter.de/mikrowebsvn/filedetails.php?repname=FlightCtrl&path=%2Fbranches%2FV0.72p+Code+Redesign+killagreg%2Fuart0.c
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 */
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ISR(USART0_RX_vect, ISR_BLOCK) {
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    uint8_t c;
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    // catch the received byte
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    c = UDR0;
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    if (rxd_buffer_locked) return; // if rxd buffer is locked immediately return
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    static uint16_t crc;
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    static uint8_t ptr_rxd_buffer = 0;
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    static uint8_t c1 = 0;
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    static uint8_t c2 = 0;
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    static uint8_t usart_rx_ok = 0;
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    uint8_t crc1, crc2;
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    // the rxd buffer is unlocked
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    if (usart_rx_ok == 0) {
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        // if ((c2 == '#') && (c1 == 'b' || c1 == 'c') && (c == 'D' || c == 'V' || c == 'O')) {
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        if ((c2 == '#') && (c1 == 'b' || c1 == 'c') &&
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#if FCONLY
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            (c == 'V' || c == 'D' || c == 'Q' || c == 'L')) { // version, debug, settings, LCD
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#else
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            (c == 'V' || c == 'O' || c == 'Q')) { // version, OSD, settings
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#endif
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                usart_rx_ok = 1;
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                rxd_buffer[ptr_rxd_buffer++] = c2;
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                crc = c2;
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                rxd_buffer[ptr_rxd_buffer++] = c1;
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                crc += c1;
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                rxd_buffer[ptr_rxd_buffer++] = c;
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                crc += c;
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                c2 = 0;
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                c1 = 0;
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            } else {
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            c2 = c1;
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            c1 = c;
157
        }
158
    } else if (ptr_rxd_buffer < RXD_BUFFER_LEN) { // collect incomming bytes
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        if (c != '\r') { // no termination character
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            rxd_buffer[ptr_rxd_buffer++] = c; // copy byte to rxd buffer
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            crc += c; // update crc
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        } else { // termination character was received
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            // the last 2 bytes are no subject for checksum calculation
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            // they are the checksum itself
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            crc -= rxd_buffer[ptr_rxd_buffer - 2];
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            crc -= rxd_buffer[ptr_rxd_buffer - 1];
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            // calculate checksum from transmitted data
168
            crc %= 4096;
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            crc1 = '=' + crc / 64;
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            crc2 = '=' + crc % 64;
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            // compare checksum to transmitted checksum bytes
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            if ((crc1 == rxd_buffer[ptr_rxd_buffer - 2]) && (crc2 == rxd_buffer[ptr_rxd_buffer - 1])) { // checksum valid
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                rxd_buffer[ptr_rxd_buffer] = '\r'; // set termination character
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                ReceivedBytes = ptr_rxd_buffer + 1; // store number of received bytes
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                rxd_buffer_locked = 1; // lock the rxd buffer
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                if (rxd_buffer[2] == 'R') {
179
                    wdt_enable(WDTO_250MS); // Reset-Commando
180
                }
181
            } else { // checksum invalid
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                rxd_buffer_locked = 0; // unlock rxd buffer
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184
            }
185
            ptr_rxd_buffer = 0; // reset rxd buffer pointer
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            usart_rx_ok = 0;
187
        }
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    } else { // rxd buffer overrun
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        ptr_rxd_buffer = 0; // reset rxd buffer
190
        rxd_buffer_locked = 0; // unlock rxd buffer
191
        usart_rx_ok = 0;
192
 
193
    }
194
}
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196
/**
197
 * Decode the recevied Buffer
198
 * portions taken and adapted from
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 * http://svn.mikrokopter.de/mikrowebsvn/filedetails.php?repname=FlightCtrl&path=%2Ftags%2FV0.72p%2Fuart.c
200
 */
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void Decode64(void) {
202
    uint8_t a, b, c, d;
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    uint8_t x, y, z;
204
    uint8_t ptrIn = 3;
205
    uint8_t ptrOut = 3;
206
    uint8_t len = ReceivedBytes - 6;
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208
    while (len) {
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        a = rxd_buffer[ptrIn++] - '=';
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        b = rxd_buffer[ptrIn++] - '=';
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        c = rxd_buffer[ptrIn++] - '=';
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        d = rxd_buffer[ptrIn++] - '=';
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214
        x = (a << 2) | (b >> 4);
215
        y = ((b & 0x0f) << 4) | (c >> 2);
216
        z = ((c & 0x03) << 6) | d;
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218
        if (len--) rxd_buffer[ptrOut++] = x;
219
        else break;
220
        if (len--) rxd_buffer[ptrOut++] = y;
221
        else break;
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        if (len--) rxd_buffer[ptrOut++] = z;
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        else break;
224
    }
225
    pRxData = &rxd_buffer[3];
226
    RxDataLen = ptrOut - 3;
227
}
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229
/**
230
 * request Data through USART in special MK format by adding checksum and
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 * encode data in modified Base64
232
 * portions taken and adapted from
233
 * http://svn.mikrokopter.de/mikrowebsvn/filedetails.php?repname=FlightCtrl&path=%2Ftags%2FV0.72p%2Fuart.c
234
 */
235
void sendMKData(unsigned char cmd, unsigned char addr, unsigned char *snd, unsigned char len) {
236
    unsigned int pt = 0;
237
    unsigned char a, b, c;
238
    unsigned char ptr = 0;
239
 
240
    txd_buffer[pt++] = '#'; // Start-Byte
241
    txd_buffer[pt++] = 'a' + addr; // Adress
242
    txd_buffer[pt++] = cmd; // Command
243
    while (len) {
244
        if (len) {
245
            a = snd[ptr++];
246
            len--;
247
        } else a = 0;
248
        if (len) {
249
            b = snd[ptr++];
250
            len--;
251
        } else b = 0;
252
        if (len) {
253
            c = snd[ptr++];
254
            len--;
255
        } else c = 0;
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        txd_buffer[pt++] = '=' + (a >> 2);
257
        txd_buffer[pt++] = '=' + (((a & 0x03) << 4) | ((b & 0xf0) >> 4));
258
        txd_buffer[pt++] = '=' + (((b & 0x0f) << 2) | ((c & 0xc0) >> 6));
259
        txd_buffer[pt++] = '=' + (c & 0x3f);
260
    }
261
 
262
    // add crc
263
    unsigned int tmpCRC = 0, i;
264
    for (i = 0; i < pt; i++) {
265
        tmpCRC += txd_buffer[i];
266
    }
267
    tmpCRC %= 4096;
268
    txd_buffer[i++] = '=' + tmpCRC / 64;
269
    txd_buffer[i++] = '=' + tmpCRC % 64;
270
    txd_buffer[i++] = '\r';
271
 
272
    usart0_puts((char*)txd_buffer);
273
}
274
 
275
/**
276
 * short script to directly send a request thorugh usart including en- and disabling it
277
 * where <address> is the address of the receipient, <label> is which data set to request
278
 * and <ms> represents the milliseconds delay between data
279
 */
280
void usart0_request_mk_data(uint8_t address, char label, uint8_t ms) {
281
    // re-enable TXD pin
282
    usart0_EnableTXD();
283
 
284
    unsigned char mstenth = ms / 10;
285
    sendMKData(label, address, &mstenth, 1);
286
    // wait until UDR ready
287
    while (!(UCSR0A & (1 << UDRE0)));
288
    // disable TXD pin again
289
    usart0_DisableTXD();
290
}
291
 
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