lora低功耗模式以及组网简单分析

上面的DIO maping 看懂就比较好理解了，DIO0,DIO1,DIO3,

发送和接收都可以触发中断，cad模式需要使用CADDetected和CADDone。

CADDetected这个中断就是有数据接收了，触发进入接收模式，前导码个数的计算还是比较简单的。

从上图可以看出，若要可靠唤醒 WOR ，发送包的前导码必须大于 T1+2*T2 才能可靠唤醒。

TS=2^SF/BW 这个值是一个字节传输所用的时间，发送前导码的个数对应的的时间要不小于T1+2*T2才能唤醒。

举个例子：SF=9,BW=125K,传输一个码元的时间就是TS=2^SF/BW=2^9/125K=4.1ms/symb，

睡眠时间加上CAD时间除以单个码元的时间就是合理的前导码长度，这个长度在一个周期内足以唤醒模块。就是发包的时间有点久。

        lora_write(0x20,0x03)--前导码长度
        lora_write(0x21,0xec)--前导码长度

目前使用2017年在stm32平台开发的lora dtu,现在移植到lua 的平台。

想要实现实时通信，可以借助运营商基站工作原理（通信原理），蜂窝通信，一回事，使用一组公共信道（收发上行和下行，注册使用），然后从机使用公共信道注册，rssi符合要求，分配一组上行和下行信道给其使用。

local lora = {}
local sys = require "sys"


local spiId = 2
local _nss=13
local _dio0=8
local _dio1=4
local _dio3=5
local MC1={
  BW125=0x70,
  BW250=0x80,
  BW500=0x90,
  BW150=0x00
}

local MC2={
  FSK=0x00,
  SF6=0x60,
  SF7=0x70,
  SF8=0x80,
  SF9=0x90,
  SF10=0xA0,
  SF11=0xB0,
  SF12=0xC0
}

-- MC1["4/5"]=0x02
-- MC1["4/6"]=0x04
-- MC1["4/7"]=0x06
-- MC1["4/8"]=0x08
local _freq=470000000
local _bw=MC1.BW125
local _sf=MC2.SF9


local cspin = gpio.setup(_nss, 1)
local rst = gpio.setup(9, 1)

--收发数据
local function sendRecv(data,len)
    local r = ""
    cspin(0)
    if data then spi.send(spiId,data) end
    if len then r = spi.recv(spiId,len) end
    cspin(1)
    return r
end

local function lora_read(addr)
	return string.byte(sendRecv(string.char(addr),1))
end

local function lora_write(addr,value)
	cspin(0)
	spi.send(spiId,string.char(addr+0x80,value))
	cspin(1)
end
local function setFreq(freqHz)
  --  local FRF_MSB=0x06
  --  local FRF_MID=0x07
  --  local FRF_LSB=0x08

	local frfMsb,frfMid,frfLsb=0x75,0x80,0x00
	local frf=(freqHz/1000*2^11)/125
	frfMsb = (frf>>16)%256 
	frfMid = (frf>>8)%256
	frfLsb = (frf>>0)%256

	lora_write(0x06,frfMsb)
	lora_write(0x07,frfMid)
	lora_write(0x08,frfLsb)
	print(string.format("%0d hz %02X %02X %02X ",freqHz,frfMsb,frfMid,frfLsb))

end


local function setRate(sf,bw,cr,crc,iiq,powe)
  --  local SF10=0xA0
  --  local SF11=0xB0
  --  local SF12=0xC0
  --  local PA_CONFIG=0x09
  --  local MODEM_CONFIG1=0x1D
  --  local MODEM_CONFIG2=0x1E
  --  local MODEM_CONFIG3=0x26
  --  local SYMB_TIMEOUT_LSB=0x1F
  --  local INVERT_IQ=0x33

  local mc1=bit.bor(bw,cr)
  local mc2=bit.bor(sf,crc)
  --local mc3=0x04
  local mc3=0x00 -- no AGC
  if (sf == 0xB0 or sf == 0xC0) then mc3=0x08 end -- MC2.SF11=0xB0, MC2.SF12=0xC0
  local stl=0x08
  if (sf == 0xA0 or sf == 0xB0 or sf == 0xC0) then stl=0x05 end

  local pac 
  if powe > 17 then pac = 0x8F               -- 17dbm
  elseif powe < -3  then pac = 0x20          -- -3dbm
  elseif powe <= 12 then pac = 0x20+powe+3   -- -3dbm .. 12dbm
  else pac = 0x80+powe-2                     -- 13dbm .. 16dbm          
  end
  lora_write(0x09,pac)--发射功率
  lora_write(0x1D,mc1)
  lora_write(0x1E,mc2)
  lora_write(0x26,mc3)
  lora_write(0x1F,stl)
  lora_write(0x33,iiq)
end

local function setChannel(freq,sf)
  --  local HOP_PERIOD=0x24
  --  local FIFO_ADDR_PTR=0x0D
  --  local FIFO_RX_BASE_AD=0x0F
  --  local CR4_5=0x02
  --  local CRC_ON=0x04
  setFreq(freq)
  setRate(sf,_bw,0x02,0x04,0x27,14) -- CR4/5=0x02, CRC_ON=0x04
  lora_write(0x24,0x00)
  lora_write(0x0D,lora_read(0x0F))
end

--射频接收数据
local function RcvData()
    local count = lora_read(0x13)--获取数据长度
    lora_write(0x0D,lora_read(0x10))--指针需要手动清零
	return sendRecv(string.char(0x00),count)--读数据		
end

--DIO0--RxDone------------------------------------------------------
local getCount=0
local function dio0handler()
	lora_write(0x12,0xff)--清除全部的中断标志位
	if lora_read(0x40) == 0x40 then
		print("TxDone")
		if station_Module=="main" then --主站
			Rx_mode("lora")		
		end	
	else
		print("RxDone")
		local data_buff=RcvData()
		local pkt_rssi=lora_read(0x1A)
		local rssi=lora_read(0x1B)
		pkt_rssi=-137+16/15*pkt_rssi
		getCount=getCount+1
		local buff=string.format("rssi:%d,pkt_rssi:%f,getCount:%d.",rssi,pkt_rssi,getCount)
		print(data_buff,#data_buff,buff)
		
		if station_Module=="main" then --主站
			--RFSend(buff,"wor")	
		else
			RFSend(buff,"lora")
		end		
			
	end
	
end
--DIO1--CADDetected------------------------------------------------------
local function dio1handler()
	Rx_mode("wor")
	print("CADDetected")
	lora_write(0x12,0xff)--清除全部的中断标志位
	sys.timerStart(RF_Sleepmode,4000)
end
--DIO3---CADDone------------------------------------------------------
local function dio3handler()
	print("CADDone")
	lora_write(0x12,0xff)--清除全部的中断标志位
	RF_Sleepmode()
	
end

--接收模式
function Rx_mode(flag)

--local REG_LR_OPMODE			= 0x01
--local REG_LR_PREAMBLEMSB      = 0x20 
--local REG_LR_PREAMBLELSB      = 0x21 
--local REG_LR_PAYLOADLENGTH 	= 0x22 
--local RFLR_OPMODE_STANDBY     = 0x01
--local REG_LR_DIOMAPPING1      = 0x40
--local RFLR_DIOMAPPING1_DIO0_00= 0x00
--local REG_LR_FIFOADDRPTR      = 0x0D
--local RFLR_OPMODE_RECEIVER    = 0x05
--local REG_LR_IRQFLAGS		 	= 0x12
	--gpio.close(_dio0)
	gpio.close(_dio1)
	gpio.close(_dio3)
	setConfig(cid,"rxd")
	lora_write(0x01,0x81)  -- set mode LoRa standby
	if flag=="wor" then	
		lora_write(0x20,0x03)--前导码长度
		lora_write(0x21,0xec)--前导码长度
	elseif flag=="lora" then
		lora_write(0x20,0)--前导码长度
		lora_write(0x21,10)--前导码长度
	end		
    lora_write(0x40,0x00)-- 把DIO0-RXDONE标志位写入中断映射寄存器	
    lora_write(0x12,0xff)-- clear interrupt flags                                
    gpio.setup(_dio0,dio0handler,gpio.PULLDOWN,gpio.RISING)  
    lora_write(0x0D,lora_read(0x0E))
	lora_write(0x01, 0x85)--set mode LoRa rxContinuous    

end
--发送数据
function RFSend(SendBuf,flag)
--local REG_LR_OPMODE			= 0x01
--local REG_LR_PREAMBLEMSB      = 0x20 
--local REG_LR_PREAMBLELSB      = 0x21 
--local REG_LR_PAYLOADLENGTH 	= 0x22 
--local REG_LR_FIFOADDRPTR      = 0x0D 
--local REG_LR_IRQFLAGS         = 0x12 
--local REG_LR_IRQFLAGSMASK     = 0x11 
--local REG_LR_DIOMAPPING1      = 0x40
--local RFLR_IRQFLAGS_TXDONE    = 0x08
	setConfig(cid,"txd")
	gpio.close(_dio0)
	gpio.close(_dio1)
	gpio.close(_dio3)
	lora_write(0x01,0x81)	 
	if flag=="wor" then	
		lora_write(0x20,0x03)--前导码长度
		lora_write(0x21,0xec)--前导码长度
	elseif flag=="lora" then
		lora_write(0x20,0)--前导码长度
		lora_write(0x21,10)--前导码长度
	end		
	lora_write(0x40,0x40)--RFLR_DIOMAPPING1_DIO0_01
	lora_write(0x12,0xff)	--clear interrupt flags
	gpio.setup(_dio0,dio0handler,gpio.PULLDOWN,gpio.RISING)
	lora_write(0x0D,lora_read(0x0E)) 
	lora_write(0x22,#SendBuf)  --发送数据的长度
	sendRecv(string.char(0x00+0x80)..SendBuf)
	lora_write(0x01,0x83)--send
	print("RFSend",SendBuf)

end

function RF_Sleepmode()
	lora_write(0x01,0x81)     
    lora_write(0x12,0xff)                          
    lora_write(0x01,0x80)--sleep 
	gpio.close(_dio0)
	gpio.close(_dio1)
	gpio.close(_dio3)
	print("RF_Sleepmode")
	--esp32.enterLightSleep(esp32.RTC, 4 * 1000 * 1000)
	--RF_CAD_Sample()
	sys.timerStart(RF_CAD_Sample ,4000)
end
-- 说明: DIO1--CADDetected    DIO3---CADDone
-- 说明     :   采样时间约为(2^SF+32)/BW
function RF_CAD_Sample()
--local RFLR_DIOMAPPING1_DIO3_00    =   0x00
--local RFLR_DIOMAPPING1_DIO1_10    =   0x20 
	gpio.close(_dio0)
	gpio.setup(_dio1,dio1handler,gpio.PULLDOWN,gpio.RISING)
	gpio.setup(_dio3,dio3handler,gpio.PULLDOWN,gpio.RISING)
	setConfig(cid,"rxd")
    lora_write(0x01,0x81)
    lora_write(0x20,0x1f)--设置前导码长度为最长
    lora_write(0x21,0x48)
    lora_write(0x40,0x20)--dio3:CadDone.dio1:CadDetected  RFLR_DIOMAPPING1_DIO3_00 | RFLR_DIOMAPPING1_DIO1_10  
    lora_write(0x01,0x87)--cad 
	lora_write(0x12,0xff)--clear interrupt flags
	print("RF_CAD_Sample")
	
end
station_Module="main1"
cid = 99991234
function setConfig(cid,rxtx)
	local RFoffset=(cid % 250)* 200000
	local RF=420000000
	if rxtx=="rxd" then--接收
		if station_Module=="main" then --主站
			RF=420000000 + RFoffset
		else
			RF=470000000 + RFoffset
		end
	else --发送
		if station_Module=="main" then
			RF=470000000 + RFoffset
		else
			RF=420000000 + RFoffset
		end
	end
	setChannel(RF,MC2.SF9)
end
function lora.sxInit()

    rst(0)
	local result = spi.setup(spiId, _nss,0,0,8,10000)
    print("open",result)
    if result ~= 0 then--返回值为0，表示打开成功
        print("spi open error",result)
    end
	rst(1)
	if lora_read(0x42) == 0x12 and lora_read(0x44)==0x2D then
		print("start init")
	else 
		print("Unknown radio")
		--return
	end
--local REG_LR_MODEMCONFIG3    =     0x26
--local REG_LR_MODEMCONFIG1    =    0x1D 
--local REG_LR_MODEMCONFIG2    =    0x1E 
--local REG_LR_PREAMBLELSB     = 0x21	
--local REG_LR_PARAMP          =  0x0A
	lora_write(0x01,0x00)--设置为SLEEP模式   
	lora_write(0x01,0x80)--并且设置为LORA模式
	lora_write(0x01,0x81)--设置为STANDBY模式
	lora_write(0x4D,0x07)--最大发射功率20dmb开启
	lora_write(0x0A,0x02)-- 上升，下降的斜率设置为1000US    
	lora_write(0x0B,bit.bor(0x20,0x1B))--过流保护开启，最大承载电流为240MA  

	if station_Module == "main" then --主节点
		sys.timerLoopStart(RFSend,8000,"HELLO WORLD 0000000000000 12355555555558844442222111","wor")
		print("lora init  主节点 ok")
	else --低功耗从机
		--setChannel(_freq,MC2.SF9)
		sys.timerStart(RF_Sleepmode,500)
		print("lora init  从机 ok")
	end
	
end

return lora

以上代码可以直接使用，

下面是接线图