LoraWAN源码学习(1)–通道选择详解

文章目录

LoraWAN源码学习(1)--通道选择详解
- 入网通道配置
- 收发通道配置
- 应用层设置通道/缺省通道接口

本篇代码以EU868为例。

入网通道配置

#define EU868_JOIN_CHANNELS       ( uint16_t )( LC( 1 ) | LC( 2 ) | LC( 3 ) )

EU868入网默认打开CH1/2/3(分别对应频点868.1/868.3/868.5MHz)。入网成功后，join accept消息中CFList对通道设置，需要说明的是CFList不会对默认通道做修改，设置通道分别是CH4~8
每个通道占用3个字节，单位：100Hz
下面是join accept中CFList代码解析

//EU868默认3个通道
#define EU868_NUMB_DEFAULT_CHANNELS                 3//CFList 支持修改的通道数，EU868默认最多5个通道
#define EU868_NUMB_CHANNELS_CF_LIST          5void RegionEU868ApplyCFList( ApplyCFListParams_t* applyCFList )
{ChannelParams_t newChannel;ChannelAddParams_t channelAdd;ChannelRemoveParams_t channelRemove;// Setup default datarate rangenewChannel.DrRange.Value = ( DR_5 << 4 ) | DR_0; //设置数据速率范围 DR_0 ~ DR_5 // Size of the optional CF listif( applyCFList->Size != 16 ) //Lorawan规范中CFList是可选项，长度为16字节，具体的定义在【区域参数文档】中{return;}// Last byte is RFU, don't take it into account// EU868 的CFList设置通道不会修改默认通道EU868_NUMB_DEFAULT_CHANNELSfor( uint8_t i = 0, chanIdx = EU868_NUMB_DEFAULT_CHANNELS; chanIdx < EU868_MAX_NB_CHANNELS; i+=3, chanIdx++ ){if( chanIdx < ( EU868_NUMB_CHANNELS_CF_LIST + EU868_NUMB_DEFAULT_CHANNELS ) ){// Channel frequencynewChannel.Frequency = (uint32_t) applyCFList->Payload[i];//每个通道频率占用3个字节，单位：100HznewChannel.Frequency |= ( (uint32_t) applyCFList->Payload[i + 1] << 8 );newChannel.Frequency |= ( (uint32_t) applyCFList->Payload[i + 2] << 16 );newChannel.Frequency *= 100;// Initialize alternative frequency to 0newChannel.Rx1Frequency = 0;}else{newChannel.Frequency = 0;newChannel.DrRange.Value = 0;newChannel.Rx1Frequency = 0;}if( newChannel.Frequency != 0 ){channelAdd.NewChannel = &newChannel;channelAdd.ChannelId = chanIdx;// Try to add all channelsRegionEU868ChannelAdd( &channelAdd );//频率不为0，添加通道}else{channelRemove.ChannelId = chanIdx;RegionEU868ChannelsRemove( &channelRemove );//频率为0，删除通道}}
}

收发通道配置

参数初始化
EU868与入网一样默认打开CH1/2/3(分别对应频点868.1/868.3/868.5`MHz)，且这3个通道必须开启

void RegionEU868InitDefaults( InitDefaultsParams_t* params )
{Band_t bands[EU868_MAX_NB_BANDS] ={EU868_BAND0,EU868_BAND1,EU868_BAND2,EU868_BAND3,EU868_BAND4,};switch( params->Type ){case INIT_TYPE_INIT:{// Initialize bands//初始化bands, 结构为 { DutyCycle, TxMaxPower, LastJoinTxDoneTime, LastTxDoneTime, TimeOff }//实际使用组根据通道Channels[x].Band选择，例如通道0中Band=1，EU868_LC1中定义如下：//{ Frequency [Hz], RX1 Frequency [Hz], { ( ( DrMax << 4 ) | DrMin ) }, Band }//#define EU868_LC1     { 868100000, 0, { ( ( DR_5 << 4 ) | DR_0 ) }, 1 }memcpy1( ( uint8_t* )NvmCtx.Bands, ( uint8_t* )bands, sizeof( Band_t ) * EU868_MAX_NB_BANDS );// ChannelsNvmCtx.Channels[0] = ( ChannelParams_t ) EU868_LC1;//通道参数设置NvmCtx.Channels[1] = ( ChannelParams_t ) EU868_LC2;NvmCtx.Channels[2] = ( ChannelParams_t ) EU868_LC3;// Initialize the channels default maskNvmCtx.ChannelsDefaultMask[0] = LC( 1 ) + LC( 2 ) + LC( 3 ); //缺省使能通道，这3个通道必须开启// Update the channels maskRegionCommonChanMaskCopy( NvmCtx.ChannelsMask, NvmCtx.ChannelsDefaultMask, 1 );//使用缺省使能通道 更新使能通道break;}...case INIT_TYPE_RESTORE_DEFAULT_CHANNELS:{// Restore channels default maskNvmCtx.ChannelsMask[0] |= NvmCtx.ChannelsDefaultMask[0];//这里只是从新使能缺省通道，缺省通道之外的通道不受影响break;}default:{break;}}
}

上边只是协议栈针对每个区域初始化的配置，实际上lorawan每次发射前会调用RegionNextChannel()选择发射的信道及根据上次发射时长和发送占空比(DutyCycle)计算发射关闭时间(dutyCycleTimeOff)，还是以EU868为例。


LoRaMacStatus_t RegionEU868NextChannel( NextChanParams_t* nextChanParams, uint8_t* channel, TimerTime_t* time, TimerTime_t* aggregatedTimeOff )
{uint8_t nbEnabledChannels = 0;uint8_t delayTx = 0;uint8_t enabledChannels[EU868_MAX_NB_CHANNELS] = { 0 };TimerTime_t nextTxDelay = 0;if( RegionCommonCountChannels( NvmCtx.ChannelsMask, 0, 1 ) == 0 )//计算使能的信道数，为0则恢复默认通道{ // Reactivate default channelsNvmCtx.ChannelsMask[0] |= LC( 1 ) + LC( 2 ) + LC( 3 );}TimerTime_t elapsed = TimerGetElapsedTime( nextChanParams->LastAggrTx );if( ( nextChanParams->LastAggrTx == 0 ) || ( nextChanParams->AggrTimeOff <= elapsed ) ){// Reset Aggregated time off*aggregatedTimeOff = 0;// Update bands Time OFF// 根据NvmCtx.Bands参数计算 发送延时时间【详细计算源码单独一篇讲解】nextTxDelay = RegionCommonUpdateBandTimeOff( nextChanParams->Joined, nextChanParams->DutyCycleEnabled, NvmCtx.Bands, EU868_MAX_NB_BANDS );// Search how many channels are enabled// 获取所有使能的通道，enabledChannels[]存放使能通道的索引，nbEnabledChannels返回使能通道的个数nbEnabledChannels = CountNbOfEnabledChannels( nextChanParams->Joined, nextChanParams->Datarate,NvmCtx.ChannelsMask, NvmCtx.Channels,NvmCtx.Bands, enabledChannels, &delayTx );}
...if( nbEnabledChannels > 0 ){//如果有使能的通道，则随机选择一个，立即发送// We found a valid channel*channel = enabledChannels[randr( 0, nbEnabledChannels - 1 )];//在使能通道数组中随机返回获取一个 使能通道索引*time = 0;return LORAMAC_STATUS_OK;}...return LORAMAC_STATUS_NO_CHANNEL_FOUND;}
}

获取可以发送的通道
1. 发送通道未被使能
2. 未入网情况下，入网通道未使能
3. 数据速率不在范围内
4. 发送占空比关闭时间TimeOff 不为0

static uint8_t CountNbOfEnabledChannels( bool joined, uint8_t datarate, uint16_t* channelsMask, ChannelParams_t* channels, Band_t* bands, uint8_t* enabledChannels, uint8_t* delayTx )
{uint8_t nbEnabledChannels = 0;uint8_t delayTransmission = 0;for( uint8_t i = 0, k = 0; i < EU868_MAX_NB_CHANNELS; i += 16, k++ ){//每一组通道 channelsMask[] 为 16bitfor( uint8_t j = 0; j < 16; j++ ){if( ( channelsMask[k] & ( 1 << j ) ) != 0 )//通道第k组 j位 使能{if( channels[i + j].Frequency == 0 ){ // Check if the channel is enabledcontinue;}if( joined == false ){//没入网if( ( EU868_JOIN_CHANNELS & ( 1 << j ) ) == 0 ){//通道第k组j位 入网通道未使能continue;}}if( RegionCommonValueInRange( datarate, channels[i + j].DrRange.Fields.Min,channels[i + j].DrRange.Fields.Max ) == false ){ // Check if the current channel selection supports the given datarate//检查数据速率DR是否合法，每个通道的DR范围都有独立配置，如下两个通道范围均为 DR_0 ~ DR_5：//{ Frequency [Hz], RX1 Frequency [Hz], { ( ( DrMax << 4 ) | DrMin ) }, Band }//#define EU868_LC1      { 868100000, 0, { ( ( DR_5 << 4 ) | DR_0 ) }, 1 }//#define EU868_LC2      { 868300000, 0, { ( ( DR_5 << 4 ) | DR_0 ) }, 1 }continue;}if( bands[channels[i + j].Band].TimeOff > 0 ){ // Check if the band is available for transmission//检查通道 TimeOff 如果不为0，则需要延时发送，不计入使能通道delayTransmission++; //延时发送通道计数continue;}enabledChannels[nbEnabledChannels++] = i + j; //}}}*delayTx = delayTransmission;return nbEnabledChannels;
}

应用层设置通道/缺省通道接口

LoRaMacStatus_t LoRaMacMibSetRequestConfirm( MibRequestConfirm_t *mibSet )
{...case MIB_CHANNELS_DEFAULT_MASK: {chanMaskSet.ChannelsMaskIn = mibSet->Param.ChannelsMask;chanMaskSet.ChannelsMaskType = CHANNELS_DEFAULT_MASK;if ( RegionChanMaskSet( LoRaMacRegion, &chanMaskSet ) == false ) {status = LORAMAC_STATUS_PARAMETER_INVALID;}break;}case MIB_CHANNELS_MASK: {chanMaskSet.ChannelsMaskIn = mibSet->Param.ChannelsMask;chanMaskSet.ChannelsMaskType = CHANNELS_MASK;if ( RegionChanMaskSet( LoRaMacRegion, &chanMaskSet ) == false ) {status = LORAMAC_STATUS_PARAMETER_INVALID;}break;}...
}

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LoraWAN源码学习(1)--通道选择详解

LoraWAN源码学习(1)–通道选择详解

文章目录

入网通道配置

收发通道配置

应用层设置通道/缺省通道接口

LoraWAN源码学习(1)--通道选择详解相关推荐

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