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Jump frequencies when no frame has been received
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execuc committed Jun 14, 2016
1 parent b758da7 commit 6c7d658
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Showing 5 changed files with 108 additions and 58 deletions.
2 changes: 1 addition & 1 deletion LICENCE
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@@ -1,6 +1,6 @@
The MIT License (MIT)

Copyright (c) 2014 execuc
Copyright (c) 2016 execuc

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
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3 changes: 1 addition & 2 deletions README.md
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Expand Up @@ -81,10 +81,9 @@ Improvements
There are many improvements to do :

* Make more reliable code, first.
* Handle missing frame : for each frequency, transmitter send two frames in 8 ms. If there are lost, received will wait 16 frequency switching * 8ms to get frame. It would be interesting to jump some frequencies to retrieve the channel switching faster.
* Handle signal lost : return to initial state for example.
* Make a better state machine for this protocol with a re-factor of the code and a smaller footprint.
* Reduce execution time. State machine takes 120ms when a frame arrived and 32ms when there are nothing to do.
* Reduce execution time. State machine takes 120us when a frame arrived and 32ms when there are nothing to do.
* Implement this protocol in the multiwii project, if it useful.
* Make an arduino example with some RC servos.

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147 changes: 95 additions & 52 deletions v202_protocol.cpp
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@@ -1,13 +1,19 @@
/* v202_protocol.cpp -- Handle the v202 protocol.
*
* Copyright (C) 2014 execuc
* Copyright (C) 2016 execuc
*
* This software may be modified and distributed under the terms
* of the MIT license. See the LICENSE file for details.
*/

#include "v202_protocol.h"

const uint16_t NORMAL_TIMEOUT = 11;
const uint8_t ERROR_JUMP_FREQ = 1;
const uint8_t ERROR_WAIT_PREV_FREQ = 2;
const uint8_t ERROR_WAIT_ONE_FREQ = 3;
const uint8_t NO_ERROR = 0;

/*****************************************************************/
/*
This portion of code is extracted from https://bitbucket.org/rivig/v202/src
Expand Down Expand Up @@ -49,6 +55,8 @@ v202Protocol::v202Protocol()
mTxid[0]=0;
mTxid[1]=0;
mTxid[2]=0;
mTimeout = 9999;
mErrorTimeoutCode = NO_ERROR;

// Populate frequency for binding
// 0x18 channel is present for the 4 frequencies hopping pattern
Expand Down Expand Up @@ -91,68 +99,107 @@ void v202Protocol::init(nrf24l01p *wireless)
uint8_t v202Protocol::run( rx_values_t *rx_value )
{
uint8_t returnValue = UNKNOWN;
static uint8_t errorCnt = 0;
switch(mState)
{
case BOUND:
{
unsigned long newTime = millis();
bool incrementChannel = false;
returnValue = BOUND_NO_VALUES;
unsigned long newTime = millis();
if( mWireless->rxFlag() )
{
bool incrementChannel = false;
mWireless->resetRxFlag();

uint8_t lastCRC = 0;
while ( !mWireless->rxEmpty() )
{
mWireless->readPayload(mFrame, 16);

if( checkCRC() && checkTXaddr() )
{
// a valid frame has been received
incrementChannel = true;
errorCnt = 0;
// Discard bind frame
if( mFrame[14] != 0xc0 )
{
// Extract values
returnValue = BOUND_NEW_VALUES;
rx_value->throttle = mFrame[0];
rx_value->yaw = mFrame[1] < 0x80 ? -mFrame[1] : mFrame[1] - 0x80;
rx_value->pitch = mFrame[2] < 0x80 ? -mFrame[2] : mFrame[2] - 0x80;
rx_value->roll = mFrame[3] < 0x80 ? -mFrame[3] : mFrame[3] - 0x80;
rx_value->trim_yaw = mFrame[4] - 0x40;
rx_value->trim_pitch = mFrame[5] - 0x40;
rx_value->trim_roll = mFrame[6] - 0x40;
rx_value->flags = mFrame[14];
}
if(incrementChannel && lastCRC == mFrame[15])
continue;

if(!incrementChannel)
{
mRfChNum++;
if( mRfChNum > 15)
mRfChNum = 0;
mWireless->switchFreq(mRfChannels[mRfChNum]);
incrementChannel =true;
mTimeout = NORMAL_TIMEOUT;
mErrorTimeoutCode = NO_ERROR;
}

lastCRC=mFrame[15];

//Serial.println(newTime - mLastSignalTime);
mLastSignalTime = newTime;

// a valid frame has been received
//incrementChannel = true;
// Discard bind frame
if( mFrame[14] != 0xc0 )
{
// Extract values
returnValue = BOUND_NEW_VALUES;
rx_value->throttle = mFrame[0];
rx_value->yaw = mFrame[1] < 0x80 ? -mFrame[1] : mFrame[1] - 0x80;
rx_value->pitch = mFrame[2] < 0x80 ? -mFrame[2] : mFrame[2] - 0x80;
rx_value->roll = mFrame[3] < 0x80 ? -mFrame[3] : mFrame[3] - 0x80;
rx_value->trim_yaw = mFrame[4] - 0x40;
rx_value->trim_pitch = mFrame[5] - 0x40;
rx_value->trim_roll = mFrame[6] - 0x40;
rx_value->flags = mFrame[14];
rx_value->crc = mFrame[15];
}

}

}
if(incrementChannel)
{
mRfChNum++;
if( mRfChNum > 15)
mRfChNum = 0;
mWireless->switchFreq(mRfChannels[mRfChNum]);
}
}
else if(errorCnt == 0 && (newTime - mLastSignalTime) > 10)
{
errorCnt++;
mLastSignalTime = newTime;
mRfChNum++;
if( mRfChNum > 15)
mRfChNum = 0;
mWireless->switchFreq(mRfChannels[mRfChNum]);
}
else if( errorCnt >= 1 && (newTime - mLastSignalTime) > 140)
{
mLastSignalTime = newTime;
mRfChNum++;
}


if(incrementChannel == false && uint16_t(newTime - mLastSignalTime) > mTimeout)
{
mErrorTimeoutCode++;

mLastSignalTime = millis();
//Serial.print("e ");Serial.print(mRfChNum);Serial.print(" ");Serial.println(newTime - mLastSignalTime);
uint8_t freq_jump =0;
if(mErrorTimeoutCode == ERROR_JUMP_FREQ)
{
freq_jump = uint16_t(newTime - mLastSignalTime) / 8 + 1;
mTimeout = freq_jump * 8 + 6;
//Serial.print("1 ");
}
else if(mErrorTimeoutCode == ERROR_WAIT_PREV_FREQ)
{
freq_jump = 10;
mTimeout = 120;
//Serial.print("2 ");
}
else //if(mErrorTimeoutCode == ERROR_WAIT_ONE_FREQ)
{
freq_jump = random(1, 15);
mTimeout = 250;
//Serial.print("3 ");
}


mRfChNum+=freq_jump;
if( mRfChNum > 15)
mRfChNum = 0;
mRfChNum = mRfChNum % 16;
mWireless->switchFreq(mRfChannels[mRfChNum]);

}


//Serial.print(mRfChNum);Serial.print(" ");Serial.println(mTimeout);

}

if(mErrorTimeoutCode > 0)
returnValue = ERROR_SIGNAL_LOST;


}
break;
// Initial state
Expand Down Expand Up @@ -205,8 +252,6 @@ uint8_t v202Protocol::run( rx_values_t *rx_value )

// Wait on the first frequency of TX
case WAIT_FIRST_SYNCHRO:
{
unsigned long newTime = millis();
returnValue = BIND_IN_PROGRESS;
if( mWireless->rxFlag() )
{
Expand All @@ -215,11 +260,10 @@ uint8_t v202Protocol::run( rx_values_t *rx_value )
while ( !mWireless->rxEmpty() )
{
mWireless->readPayload(mFrame, 16);
if( checkCRC() )
if( checkCRC() && mFrame[14] != 0xc0 && checkTXaddr())
{
incrementChannel = true;
mState = BOUND;
mLastSignalTime = newTime;
}
}

Expand All @@ -233,10 +277,9 @@ uint8_t v202Protocol::run( rx_values_t *rx_value )
}
}
break;
}
// Not implement for the moment
case SIGNAL_LOST:
returnValue = BIND_IN_PROGRESS;
returnValue = ERROR_SIGNAL_LOST;
break;

default:
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5 changes: 4 additions & 1 deletion v202_protocol.h
View file
@@ -1,6 +1,6 @@
/* v202_protocol.h -- Handle the v202 protocol.
*
* Copyright (C) 2014 execuc
* Copyright (C) 2016 execuc
*
* This software may be modified and distributed under the terms
* of the MIT license. See the LICENSE file for details.
Expand All @@ -22,6 +22,7 @@ typedef struct __attribute__((__packed__)) {
int8_t trim_pitch;
int8_t trim_roll;
uint8_t flags;
uint8_t crc;
} rx_values_t;


Expand Down Expand Up @@ -64,6 +65,8 @@ class v202Protocol
uint8_t mRfChNum;
uint8_t mFrame[16];
uint8_t mState;
uint8_t mErrorTimeoutCode;
uint16_t mTimeout;
unsigned long mLastSignalTime;
};
#endif /* V202_PROTOCOL_H_ */
9 changes: 7 additions & 2 deletions v202_rx.ino
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@@ -1,6 +1,6 @@
/* v202_rx.ino -- An arduino sketch to test the protocol v202
*
* Copyright (C) 2014 execuc
* Copyright (C) 2016 execuc
*
* This software may be modified and distributed under the terms
* of the MIT license. See the LICENSE file for details.
Expand Down Expand Up @@ -58,13 +58,18 @@ void loop()
Serial.print("\t"); Serial.print(rxValues.trim_yaw);
Serial.print("\t"); Serial.print(rxValues.trim_pitch);
Serial.print("\t"); Serial.print(rxValues.trim_roll);
Serial.print("\t"); Serial.println(rxValues.flags);
Serial.print("\t"); Serial.print(rxValues.flags);
Serial.print("\t"); Serial.println(rxValues.crc);
//time = newTime;
break;

case BOUND_NO_VALUES:
//Serial.print(newTime - time); Serial.println(" : ----"); // 32ms for 16Mhz
break;

case ERROR_SIGNAL_LOST:
//Serial.print(newTime - time); Serial.println(" : ----")
break;

default:
break;
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