ESP8266 Community Forum

- Sun Feb 07, 2016 12:20 pm #40628 I'm looking for help on connecting multiple sensors to the one wire bus. I have three (and would like to add more) temp sensors on the onewire bus and can read one but I don't understand the code examples well enough to find all the sensors. I've searched but not found any example code. Below is what I tried to find all devices on the onewire bus but it only repeatedly finds the same device:

Code: Select allpin = 4
ow.setup(pin)
count = 0
newaddr = nil
addr = nil
addrs = {}
i = 0
ow.reset_search(pin)
repeat
  count = count + 1
  newaddr = ow.search(pin)
  if (newaddr ~= nil) then
     addrs[i]=newaddr
     print("i: ",i,"addr: ",newaddr:byte(1,8))
     i = i + 1
  end
  tmr.wdclr()
until((count > 100))

- Tue Feb 09, 2016 1:05 pm #40807 I have 6x ds18b20 sensors monitoring our hot water tank together with the flow and return pipework.
The data is then uploaded to ThinkSpeak every minute. It can be seen here
https://thingspeak.com/channels/79123

I have attached a lua code snippet which is now stable and working well on my setup.
You can modify it to your needs ie 3x sensors and the temperature data will be returned in t1 to t3

Things to note:
Needs the module ds18b20.lua to run. Download from
https://github.com/StormTrooper/ESP8266 ... s18b20.lua

I use gpio0 just change to suit your setup

Works with Integer firmware but needs the one wire module.
Get the custom firmware from nodemcu-build.com and check the box 1-wire

A drawback was that after first power up 85 deg C is returned. To overcome this I added a 750mSec delay (tmr.delay(750000)) in the ds18b20.lua module at line 85.
This slows the reading time for each sensor, but it works.

Hope this helps

Code: Select all 
-- One Wire DS18B20 function for 6 sensors
-- Jeepers01 February 2016
--
-- call function with getDSdata() as required
-- t1 to t6 sequence is as I had labelled them and not the unique ID sequence
-- Hence the sequence is t1,t5,t6,t2,t3,t4
-- Module ds18b20.lua is required
--
   gpio= {[0]=3,[2]=4,[4]=2,[5]=1,[12]=6,[13]=7,[14]=5,[15]=8,[16]=0}
--
function getDSdata()
    pin=gpio[0] -- connect the signal wire to pin GPIO0
    t=require("ds18b20")
    t.setup(pin) -- gpio0
    addrs=t.addrs()
    node_id = node.chipid()
    print("Total Sensors.: "..table.getn(addrs).." ")
    print("Sensor Type...: "..node_id.." ")
    hex_format="%02X%02X%02X%02X%02X%02X%02X%02X"
    sensor_count=table.getn(addrs)
    if (sensor_count>0) then
      for i=1,sensor_count do
        sid=string.format(hex_format,string.byte(addrs[i],1,9))
        print("t"..i.." Unique ID  : "..sid.." ")
        tmr.wdclr()
      end
    end
      t1 = t.read(addrs[1],t.C)
      t5 = t.read(addrs[2],t.C)
      t6 = t.read(addrs[3],t.C)   
      t2 = t.read(addrs[4],t.C)
      t3 = t.read(addrs[5],t.C)   
      t4 = t.read(addrs[6],t.C)    
      print("Temp t1 Lower.: "..t1.." deg C")
      print("Temp t2 Upper.: "..t2.." deg C")
      print("Temp t3 Middle: "..t3.." deg C")
      print("Temp t4 Top...: "..t4.." deg C")
      print("Temp t5 Flow..: "..t5.." deg C")    
      print("Temp t6 Return: "..t6.." deg C")    
-- Cleanup
    t = nil
    ds18b20 = nil
    package.loaded["ds18b20"]=nil
end


- Tue Sep 13, 2016 4:55 am #55010 Hi. I have already surfed around for days and also tried your example but struggeling with the bus connected device adressing. Even i have connect 3 sensors which are working standalone, i get always 0 from the table number back so it always finds only the first sensor. My firmware is "nodemcu_float_0.9.6-dev_20150704"

Sensor count is always 0

Total Sensors.: 0
Sensor Type...: 13579964
0
Temp t1 Top.: 25.25.2500 deg C
Temp t2 Mid.: 25.25.2500 deg C

What i have tried so far where 1 Sensor is working but more are not recognized :
GPIO with buildin Pullup
GPIO configured as OUTPUT
external Pullup
parasite mode for the sensor
external Power
10 different sensors (all are working)
build in a BUS query delay ...
ds18b20.lua from NodeMCU
your mentioned ds18b20.lua from stormtroppers
result is always same sh** ....

So only thing i can emagine is the Firmware. Any other ideas ? Any help would be much appreciated.
best regards
/Lord Richard of Kerry/

Code: Select all--
   gpio= {[0]=3,[2]=4,[4]=2,[5]=1,[12]=6,[13]=7,[14]=5,[15]=8,[16]=0}
--


function getDSdata()
    pin=gpio[2] -- connect the signal wire to pin 4 /GPIO2
    t=require("ds18b20")
    t.setup(pin) -- gpio2
    addrs=t.addrs()
    node_id = node.chipid()
    print("Total Sensors.: "..table.getn(addrs).." ")
    print("Sensor Type...: "..node_id.." ")
    hex_format="%02X%02X%02X%02X%02X%02X%02X%02X"
    sensor_count=table.getn(addrs)
    if (sensor_count>0) then
      for i=1,sensor_count do
        sid=string.format(hex_format,string.byte(addrs[i],1,9))
        print("t"..i.." Unique ID  : "..sid.." ")
        tmr.wdclr()
      end
    end
      t1 = t.read(addrs[1],t.C)
      t2 = t.read(addrs[2],t.C)
     t3 = t.read(addrs[3],t.C)
      print("Temp t1 Top.: "..t1.." deg C")
      print("Temp t2 Mid.: "..t2.." deg C")
      print("Temp t2 Bottom.: "..t2.." deg C")
   
-- Cleanup
    t = nil
    ds18b20 = nil
    package.loaded["ds18b20"]=nil
end

Code: Select allfunction addrs()
  setup(pin)
  tbl = {}
  ow.reset_search(pin)
  repeat
    tmr.delay(750000)
   addr = ow.search(pin)
    if(addr ~= nil) then
      table.insert(tbl, addr)
    end
    tmr.wdclr()
  until (addr == nil)
  ow.reset_search(pin)
  return tbl
end

UPDATE
Shortly after sending this post i have found a solution ...... Problem is explained in below given thread and sorted by updating to a new firmware https://github.com/nodemcu/nodemcu-firmware/issues/429

Thanks anyway !

- Mon Jan 09, 2017 12:09 pm #60728 Be careful if using module ds18b20.lua from https://github.com/StormTrooper/ESP8266-Temperature-Sensor/blob/master/ds18b20.lua Author used that most probably only for positive temperatures (water temperature? ). If you try to use it for measuring of outdoor temperature you need to implement fix for negative values. Following snippet of code is replacement of lines 98-105.

Code: Select all      if (crc == data:byte(9)) then
        t = (data:byte(1) + data:byte(2) * 256)
        if (t > 32767) then
          t = t - 65535
        end
        if(unit == nil or unit == C) then
           t = t * 625
        elseif(unit == F) then
          t = t * 1125 + 320000
        elseif(unit == K) then
          t = t * 625 + 2731500
        else