/*********************************************************
					Multiprotocol Tx code
               by Midelic and Pascal Langer(hpnuts)
	http://www.rcgroups.com/forums/showthread.php?t=2165676
    https://github.com/pascallanger/DIY-Multiprotocol-TX-Module/edit/master/README.md

	Thanks to PhracturedBlue, Hexfet, Goebish and all protocol developers
				Ported  from deviation firmware 

 This project 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 3 of the License, or
 (at your option) any later version.

 Multiprotocol 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 Multiprotocol.  If not, see <http://www.gnu.org/licenses/>.
*/
#include <avr/eeprom.h>
#include <avr/pgmspace.h>
#include <util/delay.h>
#include "Multiprotocol.h"

//Multiprotocol module configuration file
#include "_Config.h"

//Global constants/variables
uint32_t MProtocol_id;//tx id,
uint32_t MProtocol_id_master;
uint32_t Model_fixed_id=0;
uint32_t fixed_id;
uint8_t  cyrfmfg_id[6];//for dsm2 and devo
uint32_t blink=0;
//
uint16_t counter;
uint8_t  channel;
uint8_t  packet[40];

#define NUM_CHN 16
// Servo data
uint16_t Servo_data[NUM_CHN];
uint8_t  Servo_AUX;

// Protocol variables
uint8_t  rx_tx_addr[5];
uint8_t  phase;
uint16_t bind_counter;
uint8_t  bind_phase;
uint8_t  binding_idx;
uint32_t packet_counter;
uint16_t packet_period;
uint8_t  packet_count;
uint8_t  packet_sent;
uint8_t  packet_length;
uint8_t  hopping_frequency[23];
uint8_t  *hopping_frequency_ptr;
uint8_t  hopping_frequency_no=0;
uint8_t  rf_ch_num;
uint8_t  throttle, rudder, elevator, aileron;
uint8_t  flags;
uint16_t crc;
//
uint32_t state;
uint8_t  len;
uint8_t  RX_num;

// Mode_select variables
uint8_t mode_select;
uint8_t protocol_flags=0,protocol_flags2=0;

// PPM variable
volatile uint16_t PPM_data[NUM_CHN];

// Serial variables
#define RXBUFFER_SIZE 25
#define TXBUFFER_SIZE 12
volatile uint8_t rx_buff[RXBUFFER_SIZE];
volatile uint8_t rx_ok_buff[RXBUFFER_SIZE];
volatile uint8_t tx_buff[TXBUFFER_SIZE];
volatile uint8_t idx = 0;

//Serial protocol
uint8_t sub_protocol;
uint8_t option;
uint8_t cur_protocol[2];
uint8_t prev_protocol=0;

// Telemetry
#define MAX_PKT 27
uint8_t pkt[MAX_PKT];//telemetry receiving packets
#if defined(TELEMETRY)
	uint8_t pktt[MAX_PKT];//telemetry receiving packets
	volatile uint8_t tx_head;
	volatile uint8_t tx_tail;
	uint8_t v_lipo;
	int16_t RSSI_dBm;
	//const uint8_t RSSI_offset=72;//69 71.72 values db
	uint8_t telemetry_link=0; 
	uint8_t telemetry_counter=0;
#endif 

// Callback
typedef uint16_t (*void_function_t) (void);//pointer to a function with no parameters which return an uint16_t integer
void_function_t remote_callback = 0;
static void CheckTimer(uint16_t (*cb)(void));

// Init
void setup()
{
	// General pinout
	DDRD = (1<<CS_pin)|(1<<SDI_pin)|(1<<SCLK_pin)|(1<<CS_pin)|(1<< CC25_CSN_pin);
	DDRC = (1<<CTRL1)|(1<<CTRL2); //output
	//DDRC |= (1<<5);//RST pin A5(C5) CYRF output
	DDRB  = _BV(0)|_BV(1);
	PORTB = _BV(2)|_BV(3)|_BV(4)|_BV(5);//pullup 10,11,12 and bind button
	PORTC = _BV(0);//A0 high pullup

	// Set Chip selects
	CS_on;
	CC25_CSN_on;
	NRF_CSN_on;
	CYRF_CSN_on;
	//	Set SPI lines
	SDI_on;
	SCK_off;

	// Timer1 config
	TCCR1A = 0;
	TCCR1B = (1 << CS11);	//prescaler8, set timer1 to increment every 0.5us(16Mhz) and start timer

	// Set servos positions
	for(uint8_t i=0;i<NUM_CHN;i++)
		Servo_data[i]=1500;
	Servo_data[THROTTLE]=PPM_MIN_100;
	memcpy((void *)PPM_data,Servo_data, sizeof(Servo_data));
	
	// Read status of bind button
	if( (PINB & _BV(5)) == 0x00 )
		BIND_BUTTON_FLAG_on;	// If bind button pressed save the status for protocol id reset under hubsan

	// Read status of mode select binary switch
	// after this mode_select will be one of {0000, 0001, ..., 1111}
	mode_select=0x0F - ( ( (PINB>>2)&0x07 ) | ( (PINC<<3)&0x08) );//encoder dip switches 1,2,4,8=>B2,B3,B4,C0
//**********************************
//mode_select=14;	// here to test PPM
//**********************************

	// Update LED
	LED_OFF;
	LED_SET_OUTPUT; 

	// Read or create protocol id
	MProtocol_id_master=random_id(10,false);

	//Init RF modules
	#ifdef	CC2500_INSTALLED
		CC2500_Reset();
	#endif

	//Protocol and interrupts initialization
	if(mode_select != MODE_SERIAL)
	{ // PPM
		mode_select--;
		cur_protocol[0]	=	PPM_prot[mode_select].protocol;
		sub_protocol   	=	PPM_prot[mode_select].sub_proto;
		RX_num			=	PPM_prot[mode_select].rx_num;
		MProtocol_id	=	RX_num + MProtocol_id_master;
		option			=	PPM_prot[mode_select].option;
		if(PPM_prot[mode_select].power)		POWER_FLAG_on;
		if(PPM_prot[mode_select].autobind)	AUTOBIND_FLAG_on;
		mode_select++;

		protocol_init();

		//Configure PPM interrupt
		EICRA |=(1<<ISC11);		// The rising edge of INT1 pin D3 generates an interrupt request
		EIMSK |= (1<<INT1);		// INT1 interrupt enable
#if defined(TELEMETRY)
		PPM_Telemetry_serial_init();		// Configure serial for telemetry
#endif
	}
	else
	{ // Serial
		cur_protocol[0]=0;
		cur_protocol[1]=0;
		prev_protocol=0;
		Mprotocol_serial_init(); // Configure serial and enable RX interrupt
	}
}

// Main
void loop()
{
	if(mode_select==MODE_SERIAL && IS_RX_FLAG_on)	// Serial mode and something has been received
	{
		update_serial_data();	// Update protocol and data
		update_aux_flags();
		if(IS_CHANGE_PROTOCOL_FLAG_on)
		{ // Protocol needs to be changed
			LED_OFF;									//led off during protocol init
			module_reset();								//reset previous module
			protocol_init();							//init new protocol
			CHANGE_PROTOCOL_FLAG_off;					//done
		}
	}
	if(mode_select!=MODE_SERIAL && IS_PPM_FLAG_on)	// PPM mode and a full frame has been received
	{
		for(uint8_t i=0;i<NUM_CHN;i++)
		{ // update servo data without interrupts to prevent bad read in protocols
			cli();	// disable global int
			Servo_data[i]=PPM_data[i];
			sei();	// enable global int
		}
		update_aux_flags();
		PPM_FLAG_off;	// wait for next frame before update
	}
	update_led_status();
	#if defined(TELEMETRY)
	if( ((cur_protocol[0]&0x1F)==MODE_FRSKY) || ((cur_protocol[0]&0x1F)==MODE_HUBSAN) || ((cur_protocol[0]&0x1F)==MODE_FRSKYX) )
		frskyUpdate();
	#endif 
	if (remote_callback != 0)
		CheckTimer(remote_callback); 
}

// Update Servo_AUX flags based on servo AUX positions
static void update_aux_flags(void)
{
	Servo_AUX=0;
	for(uint8_t i=0;i<8;i++)
		if(Servo_data[AUX1+i]>PPM_SWITCH)
			Servo_AUX|=1<<i;
}

// Update led status based on binding and serial
static void update_led_status(void)
{
	if(blink<millis())
	{
		if(cur_protocol[0]==0)	// No valid serial received at least once
			blink+=BLINK_SERIAL_TIME;					//blink slowly while waiting a valid serial input
		else
			if(remote_callback == 0)
			{ // Invalid protocol
				if(IS_LED_on)							//flash to indicate invalid protocol
					blink+=BLINK_BAD_PROTO_TIME_LOW;
				else
					blink+=BLINK_BAD_PROTO_TIME_HIGH;
			}
			else
				if(IS_BIND_DONE_on)
					LED_OFF;									//bind completed -> led on
				else
					blink+=BLINK_BIND_TIME;				//blink fastly during binding
		LED_TOGGLE;
	}
}

// Protocol scheduler
static void CheckTimer(uint16_t (*cb)(void))
{ 
	uint16_t next_callback;
	uint32_t prev;
	if( (TIFR1 & (1<<OCF1A)) != 0)
	{
		cli();			// disable global int
		OCR1A=TCNT1;	// Callback should already have been called... Use "now" as new sync point.
		sei();			// enable global int
	}
	else
		while((TIFR1 & (1<<OCF1A)) == 0); // wait before callback
	prev=micros();
	next_callback=cb();
	if(prev+next_callback+50 > micros())
	{ // Callback did not took more than requested time for next callback
		if(next_callback>32000)
		{ // next_callback should not be more than 32767 so we will wait here...
			delayMicroseconds(next_callback-2000);
			cli();			// disable global int
			OCR1A=TCNT1+4000;
			sei();			// enable global int
		}
		else
		{
			cli();			// disable global int
			OCR1A+=next_callback*2;		// set compare A for callback
			sei();			// enable global int
		}
		TIFR1=(1<<OCF1A);	// clear compare A=callback flag
	}
}

// Protocol start
static void protocol_init()
{
	uint16_t next_callback=0;		// Default is immediate call back
	remote_callback = 0;

	set_rx_tx_addr(MProtocol_id);
	blink=millis();
	if(IS_BIND_BUTTON_FLAG_on)
		AUTOBIND_FLAG_on;
	if(IS_AUTOBIND_FLAG_on)
		BIND_IN_PROGRESS;			// Indicates bind in progress for blinking bind led
	else
		BIND_DONE;

	CTRL1_on;	//NRF24L01 antenna RF3 by default
	CTRL2_off;	//NRF24L01 antenna RF3 by default
	
	switch(cur_protocol[0]&0x1F)	// Init the requested protocol
	{
#if defined(FLYSKY_A7105_INO)
		case MODE_FLYSKY:
			CTRL1_off;	//antenna RF1
			next_callback = initFlySky();
			remote_callback = ReadFlySky;
			break;
#endif
#if defined(HUBSAN_A7105_INO)
		case MODE_HUBSAN:
			CTRL1_off;	//antenna RF1
			if(IS_BIND_BUTTON_FLAG_on) random_id(10,true); // Generate new ID if bind button is pressed.
			next_callback = initHubsan();
			remote_callback = ReadHubsan;
			break;
#endif
#if defined(FRSKY_CC2500_INO)
		case MODE_FRSKY:
			CTRL1_off;	//antenna RF2
			CTRL2_on;
			next_callback = initFrSky_2way();
			remote_callback = ReadFrSky_2way;
			break;
#endif
#if defined(FRSKYX_CC2500_INO)
		case MODE_FRSKYX:
			CTRL1_off;	//antenna RF2
			CTRL2_on;
			next_callback = initFrSkyX();
			remote_callback = ReadFrSkyX;
			break;
#endif
#if defined(DSM2_CYRF6936_INO)
		case MODE_DSM2:
			CTRL2_on;	//antenna RF4
			next_callback = initDsm2();
			//Servo_data[2]=1500;//before binding
			remote_callback = ReadDsm2;
			break;
#endif
#if defined(DEVO_CYRF6936_INO)
		case MODE_DEVO:
			CTRL2_on;	//antenna RF4
			next_callback = DevoInit();
			remote_callback = devo_callback;
			break;
#endif
#if defined(HISKY_NRF24L01_INO)
		case MODE_HISKY:
			next_callback=initHiSky();
			remote_callback = hisky_cb;
			break;
#endif
#if defined(V2X2_NRF24L01_INO)
		case MODE_V2X2:
			next_callback = initV2x2();
			remote_callback = ReadV2x2;
			break;
#endif
#if defined(YD717_NRF24L01_INO)
		case MODE_YD717:
			next_callback=initYD717();
			remote_callback = yd717_callback;
			break;
#endif
#if defined(KN_NRF24L01_INO)
		case MODE_KN:
			next_callback = initKN();
			remote_callback = kn_callback;
			break;
#endif
#if defined(SYMAX_NRF24L01_INO)
		case MODE_SYMAX:
			next_callback = initSymax();
			remote_callback = symax_callback;
			break;
#endif
#if defined(SLT_NRF24L01_INO)
		case MODE_SLT:
			next_callback=initSLT();
			remote_callback = SLT_callback;
			break;
#endif
#if defined(CX10_NRF24L01_INO)
		case MODE_CX10:
			next_callback=initCX10();
			remote_callback = CX10_callback;
			break;
#endif
#if defined(CG023_NRF24L01_INO)
		case MODE_CG023:
			next_callback=initCG023();
			remote_callback = CG023_callback;
			break;
#endif
#if defined(BAYANG_NRF24L01_INO)
		case MODE_BAYANG:
			next_callback=initBAYANG();
			remote_callback = BAYANG_callback;
			break;
#endif
#if defined(ESKY_NRF24L01_INO)
		case MODE_ESKY:
			next_callback=initESKY();
			remote_callback = ESKY_callback;
			break;
#endif
#if defined(MT99XX_NRF24L01_INO)
		case MODE_MT99XX:
			next_callback=initMT99XX();
			remote_callback = MT99XX_callback;
			break;
#endif
#if defined(MJXQ_NRF24L01_INO)
		case MODE_MJXQ:
			next_callback=initMJXQ();
			remote_callback = MJXQ_callback;
			break;
#endif
	}

	if(next_callback>32000)
	{ // next_callback should not be more than 32767 so we will wait here...
		delayMicroseconds(next_callback-2000);
		next_callback=2000;
	}
	cli();							// disable global int
	OCR1A=TCNT1+next_callback*2;	// set compare A for callback
	sei();							// enable global int
	TIFR1=(1<<OCF1A);				// clear compare A flag
	BIND_BUTTON_FLAG_off;			// do not bind/reset id anymore even if protocol change
}

static void update_serial_data()
{
	if(rx_ok_buff[0]&0x20)						//check range
		RANGE_FLAG_on;
	else
		RANGE_FLAG_off;		
	if(rx_ok_buff[0]&0xC0)						//check autobind(0x40) & bind(0x80) together
		AUTOBIND_FLAG_on;
	else
		AUTOBIND_FLAG_off;
	if(rx_ok_buff[1]&0x80)						//if rx_ok_buff[1] ==1,power is low ,0-power high
		POWER_FLAG_off;	//power low
	else
		POWER_FLAG_on;	//power high
				
	option=rx_ok_buff[2];

	if( ((rx_ok_buff[0]&0x5F) != (cur_protocol[0]&0x5F)) || ( (rx_ok_buff[1]&0x7F) != cur_protocol[1] ) )
	{ // New model has been selected
		prev_protocol=cur_protocol[0]&0x1F;		//store previous protocol so we can reset the module
		cur_protocol[1] = rx_ok_buff[1]&0x7F;	//store current protocol
		CHANGE_PROTOCOL_FLAG_on;				//change protocol
		sub_protocol=(rx_ok_buff[1]>>4)& 0x07;					//subprotocol no (0-7) bits 4-6
		RX_num=rx_ok_buff[1]& 0x0F;
		MProtocol_id=MProtocol_id_master+RX_num;	//personalized RX bind + rx num // rx_num bits 0---3
	}
	else
		if( ((rx_ok_buff[0]&0x80)!=0) && ((cur_protocol[0]&0x80)==0) )	// Bind flag has been set
			CHANGE_PROTOCOL_FLAG_on;			//restart protocol with bind
	cur_protocol[0] = rx_ok_buff[0];			//store current protocol

	// decode channel values
	volatile uint8_t *p=rx_ok_buff+2;
	uint8_t dec=-3;
	for(uint8_t i=0;i<NUM_CHN;i++)
	{
		dec+=3;
		if(dec>=8)
		{
			dec-=8;
			p++;
		}
		p++;
		Servo_data[i]=((((*((uint32_t *)p))>>dec)&0x7FF)*5)/8+860;	//value range 860<->2140 -125%<->+125%
	}
	RX_FLAG_off;								//data has been processed
}

static void module_reset()
{
	if(remote_callback)
	{		// previous protocol loaded
		remote_callback = 0;
		switch(prev_protocol)
		{
			case MODE_FLYSKY:
			case MODE_HUBSAN:
				A7105_Reset();
				break;
			case MODE_FRSKY:
			case MODE_FRSKYX:
				CC2500_Reset();
				break;
			case MODE_DSM2:
			case MODE_DEVO:
				CYRF_Reset();
				break;
			default:	// MODE_HISKY, MODE_V2X2, MODE_YD717, MODE_KN, MODE_SYMAX, MODE_SLT, MODE_CX10, MODE_CG023, MODE_BAYANG, MODE_ESKY, MODE_MT99XX, MODE_MJXQ
				NRF24L01_Reset();
				break;
		}
	}
}

// Channel value is converted to 8bit values full scale
uint8_t convert_channel_8b(uint8_t num)
{
	return (uint8_t) (map(limit_channel_100(num),PPM_MIN_100,PPM_MAX_100,0,255));	
}

// Channel value is converted to 8bit values to provided values scale
uint8_t convert_channel_8b_scale(uint8_t num,uint8_t min,uint8_t max)
{
	return (uint8_t) (map(limit_channel_100(num),PPM_MIN_100,PPM_MAX_100,min,max));	
}

// Channel value is converted sign + magnitude 8bit values
uint8_t convert_channel_s8b(uint8_t num)
{
	uint8_t ch;
	ch = convert_channel_8b(num);
	return (ch < 128 ? 127-ch : ch);	
}

// Channel value is converted to 10bit values
uint16_t convert_channel_10b(uint8_t num)
{
	return (uint16_t) (map(limit_channel_100(num),PPM_MIN_100,PPM_MAX_100,1,1023));
}

// Channel value is multiplied by 1.5
uint16_t convert_channel_frsky(uint8_t num)
{
	return Servo_data[num] + Servo_data[num]/2;
}

// Channel value is converted for HK310
void convert_channel_HK310(uint8_t num, uint8_t *low, uint8_t *high)
{
	uint16_t temp=0xFFFF-(4*Servo_data[num])/3;
	*low=(uint8_t)(temp&0xFF);
	*high=(uint8_t)(temp>>8);
}

// Channel value is limited to PPM_100
uint16_t limit_channel_100(uint8_t ch)
{
	if(Servo_data[ch]>PPM_MAX_100)
		return PPM_MAX_100;
	else
		if (Servo_data[ch]<PPM_MIN_100)
			return PPM_MIN_100;
	return Servo_data[ch];
}

#if defined(TELEMETRY)
void Serial_write(uint8_t data)
{
	cli();	// disable global int
	if(++tx_head>=TXBUFFER_SIZE)
		tx_head=0;
	tx_buff[tx_head]=data;
	sei();	// enable global int
	UCSR0B |= (1<<UDRIE0);//enable UDRE interrupt
}
#endif

static void Mprotocol_serial_init()
{
	#include <util/setbaud.h>	
	UBRR0H = UBRRH_VALUE;
	UBRR0L = UBRRL_VALUE;
	//Set frame format to 8 data bits, even parity, 2 stop bits
	UCSR0C |= (1<<UPM01)|(1<<USBS0)|(1<<UCSZ01)|(1<<UCSZ00);
	while ( UCSR0A & (1 << RXC0) )//flush receive buffer
		UDR0;
	//enable reception and RC complete interrupt
	UCSR0B |= (1<<RXEN0)|(1<<RXCIE0);//rx enable and interrupt
	UCSR0B |= (1<<TXEN0);//tx enable
}

#if defined(TELEMETRY)
static void PPM_Telemetry_serial_init()
{
	//9600 bauds
	UBRR0H = 0x00;
	UBRR0L = 0x67;
	//Set frame format to 8 data bits, none, 1 stop bit
	UCSR0C |= (1<<UCSZ01)|(1<<UCSZ00);
	UCSR0B |= (1<<TXEN0);//tx enable
}
#endif

// Convert 32b id to rx_tx_addr
static void set_rx_tx_addr(uint32_t id)
{ // Used by almost all protocols
	rx_tx_addr[0] = (id >> 24) & 0xFF;
	rx_tx_addr[1] = (id >> 16) & 0xFF;
	rx_tx_addr[2] = (id >>  8) & 0xFF;
	rx_tx_addr[3] = (id >>  0) & 0xFF;
	rx_tx_addr[4] = 0xC1;	// for YD717: always uses first data port
}

static uint32_t random_id(uint16_t adress, uint8_t create_new)
{
	uint32_t id;
	uint8_t txid[4];

	if (eeprom_read_byte((uint8_t*)(adress+10))==0xf0 && !create_new)
	{  // TXID exists in EEPROM
		eeprom_read_block((void*)txid,(const void*)adress,4);
		id=(txid[0] | ((uint32_t)txid[1]<<8) | ((uint32_t)txid[2]<<16) | ((uint32_t)txid[3]<<24));
	}
	else
	{ // if not generate a random ID
		randomSeed((uint32_t)analogRead(A6)<<10|analogRead(A7));//seed
		//
		id = random(0xfefefefe) + ((uint32_t)random(0xfefefefe) << 16);
		txid[0]=  (id &0xFF);
		txid[1] = ((id >> 8) & 0xFF);
		txid[2] = ((id >> 16) & 0xFF);
		txid[3] = ((id >> 24) & 0xFF);
		eeprom_write_block((const void*)txid,(void*)adress,4);
		eeprom_write_byte((uint8_t*)(adress+10),0xf0);//write bind flag in eeprom.
	}
	return id;
}

/**************************/
/**************************/
/**  Interrupt routines  **/
/**************************/
/**************************/

//PPM
ISR(INT1_vect)
{	// Interrupt on PPM pin
	static int8_t chan=-1;
	static uint16_t Prev_TCNT1=0;
	uint16_t Cur_TCNT1;

	Cur_TCNT1=TCNT1-Prev_TCNT1; // Capture current Timer1 value
	if(Cur_TCNT1<1000)
		chan=-1;				// bad frame
	else
		if(Cur_TCNT1>4840)
		{
			chan=0;				// start of frame
			PPM_FLAG_on;		// full frame present (even at startup since PPM_data has been initialized)
		}
		else
			if(chan!=-1)		// need to wait for start of frame
			{  //servo values between 500us and 2420us will end up here
				uint16_t a = Cur_TCNT1>>1;
				if(a<PPM_MIN) a=PPM_MIN;
				else if(a>PPM_MAX) a=PPM_MAX;
				PPM_data[chan]=a;
				if(chan++>=NUM_CHN)
					chan=-1;	// don't accept any new channels
			}
	Prev_TCNT1+=Cur_TCNT1;
}

//Serial RX
ISR(USART_RX_vect)
{	// RX interrupt
	if((UCSR0A&0x1C)==0)			// Check frame error, data overrun and parity error
	{ // received byte is ok to process
		if(idx==0)
		{	// Let's try to sync at this point
			if(UDR0==0x55)			// If 1st byte is 0x55 it looks ok
			{
				idx++;
				OCR1B=TCNT1+6500L;		// Full message should be received within timer of 3250us
				TIFR1=(1<<OCF1B);		// clear OCR1B match flag
				TIMSK1 |=(1<<OCIE1B);	// enable interrupt on compare B match
			}
		}
		else
		{
			rx_buff[(idx++)-1]=UDR0;	// Store received byte
			if(idx>RXBUFFER_SIZE)
			{	// A full frame has been received
				TIMSK1 &=~(1<<OCIE1B);		// disable interrupt on compare B match
				if(!IS_RX_FLAG_on)
				{ //Good frame received and main has finished with previous buffer
					for(idx=0;idx<RXBUFFER_SIZE;idx++)
						rx_ok_buff[idx]=rx_buff[idx];	// Duplicate the buffer
					RX_FLAG_on;		//flag for main to process servo data
				}
				idx=0; // start again
			}
		}
	}
	else
	{
		idx=UDR0;	// Dummy read
		idx=0;		// Error encountered discard full frame...
	}
}

//Serial timer
ISR(TIMER1_COMPB_vect)
{	// Timer1 compare B interrupt
	idx=0;
}

#if defined(TELEMETRY)
//Serial TX
ISR(USART_UDRE_vect)
{	// Transmit interrupt
	uint8_t t = tx_tail;
	if(tx_head!=t)
	{
		if(++t>=TXBUFFER_SIZE)//head 
		t=0;
		UDR0=tx_buff[t];
		tx_tail=t;
	}
	if (t == tx_head)
		UCSR0B &= ~(1<<UDRIE0); // Check if all data is transmitted . if yes disable transmitter UDRE interrupt
}
#endif