Subversion Repositories FlightCtrl

// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

// This code has been derived from the implementation of Stefan Engelke.

// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

/*

 Copyright (c) 2008 Stefan Engelke <stefan@tinkerer.eu>

 Permission is hereby granted, free of charge, to any person

 obtaining a copy of this software and associated documentation

 files (the "Software"), to deal in the Software without

 restriction, including without limitation the rights to use, copy,

 modify, merge, publish, distribute, sublicense, and/or sell copies

 of the Software, and to permit persons to whom the Software is

 furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be

 included in all copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT

 HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,

 WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

 DEALINGS IN THE SOFTWARE.

 $Id: rcdsl.c 60 2008-08-21 07:50:48Z taser $

 RCDSL.H and RCDSL.C is an INOFFICIAL implementation of the

 communication protocol used by DSL receivers of Act Europe.

 The DSL receivers have a serial communication port to connect

 two receivers in diversity mode. Each receiver is sending the

 received servo signals periodically over this port. This fact

 can be used to connect the receiver to the control unit of the

 model via UART instead of evaluating the PPM signal.

 If you have any questions, fell free to send me an e-mail.

 */

/*

 Connection of DSL to SV1 of FC:

 ( DSL Pin1 is on side of channel 4 )

 1. GND <--> pin 7 (GND)

 2. TXD <--> pin 3 (RXD1 Atmega644p)

 3. RXD <--> pin 4 (TXD1 Atmega644p) optional

 4. 5V  <--> pin 2 (5V)

 Do not connect the receiver via PPM-Sumsignal output the same time.

 Data are send at every 20 ms @ 38400 Baud 8-N-1

 Data Frame: |0xFF|0xFF|0x1F|FREQALLOC|??|RSSI|VBAT|??|CRC|10|CH0D1|CH0D0|CH1D1|CH1D0|CRC| ...etc

 FREQALLOC = 35, 40, 72

 RSSI = 0.. 255 // Received signal strength indicator

 VBAT = 0...255 // supply voltage (0.0V.. 7.8V)

 Servo Pair:   |0x1X|CHXD1|CHXD0|CHX+1D1|CHX+1D0|CRC|

 X is channel index of 1 servo value

 D1D0 is servo value as u16 in range of 7373 (1ms) to 14745 (2ms)

 there are 8 channels submitted, i.e 4 servo pairs

 Frame examples with signel received

 FFFF 1F23F079A304AD 1036012B1E6F 122AFB2AECB2 142B4D2B4404 1636872B33CE

 FFFF 1F23F079A304AD 1036002B1F6F 122AFE2AEBB0 142B4B2B4406 1636872B33CE

 FFFF 1F23F079A304AD 1035FF2B226E 122AFC2AEAB3 142B4E2B4304 1636882B33CD

 FFFF 1F23F079A304AD 1036022B1E6E 122AFB2AEEB0 142B4A2B4506 1636872B33CE

 FFFF 1F23F079A304AD 1036022B1E6E 122AFE2AEBB0 142B4B2B4406 1636882B33CD

 FFFF 1F23F079A304AD 1036012B1E6F 122AFD2AEAB2 142B4E2B4403 1636862B33CF

 FFFF 1F23F079A304AD 1036032B1D6E 122AFD2AEBB1 142B4C2B4504 1636862B33CF

 Frame examples with no signal received

 FFFF 1F23F000A30426

 FFFF 1F23F000A30426

 FFFF 1F23F000A30426

 FFFF 1F23F000A30426

 FFFF 1F23F000A30426

 FFFF 1F23F000A30426

 FFFF 1F23F000A30426

 */

#include <stdlib.h>

#include "dsl.h"

#include "rc.h"

#include "uart0.h"

uint8_t dsl_RSSI = 0;

uint8_t dsl_Battery = 0;

uint8_t dsl_Allocation = 0;

uint8_t PacketBuffer[6];

//uint8_t Jitter = 0; // same measurement as RC_Quality in rc.c

typedef union {

        int16_t Servo[2];

        uint8_t byte[4];

} ChannelPair_t;

ChannelPair_t ChannelPair;

// This function is called, when a new servo signal is properly received.

// Parameters: servo  - servo number (0-9)

//             signal - servo signal between 7373 (1ms) and 14745 (2ms)

void dsl_new_signal(uint8_t channel, int16_t signal) {

        int16_t tmp;

        uint8_t index = channel + 1; // mk channels start with 1

        //RC_Quality    = (212 * (uint16_t)dsl_RSSI) / 128; // have to be scaled approx. by a factor of 1.66 to get 200 at full level

        //if(RC_Quality > 255) RC_Quality = 255;

        // signal from  DSL-receiver is between 7373 (1ms) und 14745 (2ms).

        signal -= 11059; // shift to neutral

        signal /= 24; // scale to mk rc resolution

        if (abs(signal-PPM_in[index]) < 6) {

                if (RC_Quality < 200)

                        RC_Quality += 10;

                else

                        RC_Quality = 200;

        }

        // calculate exponential history for signal

        tmp = (3 * (PPM_in[index]) + signal) / 4;

        if (tmp > signal + 1)

                tmp--;

        else if (tmp < signal - 1)

                tmp++;

        // calculate signal difference on good signal level

        if (RC_Quality >= 195)

                PPM_diff[index] = ((tmp - PPM_in[index]) / 3) * 3; // cut off lower 3 bit for noise reduction

        else

                PPM_diff[index] = 0;

        PPM_in[index] = tmp; // update channel value

        if (index == 4) {

                NewPpmData = 0;

        }

}

// This function is called within dsl_parser(), when a complete

// data packet with valid checksum has been received.

void dsl_decode_packet(void) {

        uint8_t i;

        // check for header condition

        if ((PacketBuffer[0] & 0xF0) == 0x10) {

                if (PacketBuffer[0] == 0x1F) // separate status frame

                {

                        dsl_Allocation = PacketBuffer[1]; // Get frequency allocation

                        // ??                   = PacketBuffer[2];

                        dsl_RSSI = PacketBuffer[3]; // Get signal quality

                        dsl_Battery = PacketBuffer[4]; // Get voltage of battery supply

                        // ??                   = PacketBuffer[5];

                        if (dsl_RSSI == 0) {

                                RC_Quality = 0;

                                for (i = 0; i < 5; i++) {

                                        PPM_diff[i] = 0;

                                        PPM_in[i] = 0;

                                }

                        }

                } else // probably a channel pair

                {

                        i = PacketBuffer[0] & 0x0F; // last 4 bits of the header indicates the channel pair

                        if (i < 10)// maximum 12 channels

                        {

                                // big to little endian

                                ChannelPair.byte[1] = PacketBuffer[1];

                                ChannelPair.byte[0] = PacketBuffer[2];

                                ChannelPair.byte[3] = PacketBuffer[3];

                                ChannelPair.byte[2] = PacketBuffer[4];

                                dsl_new_signal(i, ChannelPair.Servo[0]);

                                dsl_new_signal(i + 1, ChannelPair.Servo[1]);

                        }

                }

        } // EOF header condition

}

// this function should be called within the UART RX ISR

void dsl_parser(uint8_t c) {

        static uint8_t last_c = 0;

        static uint8_t crc = 0;

        static uint8_t cnt = 0;

        static uint8_t packet_len = 0;

        // check for sync condition

        if ((c == 0xFF) && (last_c == 0xFF)) {

                cnt = 0; // reset byte counter

                crc = 0; // reset checksum

                return;

        }

        if (cnt == 0) // begin of a packet

        {

                if (c == 0x1F)

                        packet_len = 5; // a status packet has 5 bytes + crc

                else

                        packet_len = 4; // a channel pair packet has 4 bytes + crc

        }

        if (cnt > packet_len) // packet complete, crc byte received

        {

                // calculate checksum

                crc = ~crc;

                if (crc == 0xFF)

                        crc = 0xFE;

                // if crc matches decode the packet

                if (c == crc)

                        dsl_decode_packet();

                // handle next packet

                cnt = 0;

                crc = 0;

        } else // collect channel data bytes

        {

                PacketBuffer[cnt++] = c;

                crc += c;

        }

        // store last byte for sync check

        last_c = c;

}