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