ESP8266 Community Forum

- Mon Dec 29, 2014 1:52 pm #5906

But on the web page I only get 1 temperature which is always the second one like in this case 24.2500, any idea how I can get this code to print out both readings from the 2 sensors on the webpage ?

The script is really crappy - I'll have to spend some time tomorrow and play with it a little more in order to provide the web-interface.
I am just learning lua and its tables, so sorry for that
However, my example was the automated post of data to server TCP port, not sure what web page are you talking about...

- Mon Dec 29, 2014 8:33 pm #5923

Hi Sancho,
But on the web page I only get 1 temperature which is always the second one like in this case 24.2500, any idea how I can get this code to print out both readings from the 2 sensors on the webpage ?

I don't know if this helps, but I use this (which doesn't have the <0C fix, but works otherwise):

Code: Select allt=require("ds18b20")
t.setup(4)
addrs=t.addrs()

node_id = node.chipid()
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))
    sval=t.read(addrs[i],t.C)
    print("SensorID: "..node_id.."."..sid..", Value: "..sval)
    tmr.wdclr()
  end
end



Which produces this when I have three sensors connected:

SensorID: 10280400.28FF30372B04006C, Value: 18.0
SensorID: 10280400.28FF71362B0400C7, Value: 17.9375
SensorID: 10280400.28FF6F092E0400FE, Value: 17.4375

The string.format function seems to use a lot of memory. If there's a better hex conversion for a 64-bit number it would be worth replacing that.

- Tue Dec 30, 2014 4:30 am #5941 Hi Pigs Fly
I saw this code from you in another post i cannot get it to work, tied it on 0.9.2 (219) & 0.9.4 (222) it just produces :
stdin:1: attempt to compare number with nil

Hi Sancho
I don't think the script is crappy, the getTemp() function is working great it gets both my sensor readings perfectly however, although the automated post part again works exactly how I want it to work (its constantly sending the temperature of my second sensor to my web page) my skill is so low that I cannot figure out how get and send both sensor reading (whether in a single POST or 2 separate POSTS) I don't think your suggestion of a separate web interface will personalty help me as I want to incorporate the sensor reading into my own web page,

Finally sorry for the confusion when I said "web page" what i meant was: when I enter http://192.168.0.179:8080/ into chrome browser address bar and press enter it displays on the screen only the second sensor reading, its clear to me that although getTemp successfully reads both my sensors the srv=net.createServer(net.TCP) part of the code is not designed to POST both sensor readings, currently.

- Tue Dec 30, 2014 7:03 am #5952 Thanks for the explanation - now I understand.
The original script of mine was really meant for a single temp sensor. I updated it with the ability to send multiple results:

Code: Select allpin = 4
ow.setup(pin)

function bxor(a,b)
   local r = 0
   for i = 0, 31 do
      if ( a % 2 + b % 2 == 1 ) then r = r + 2^i end
      a = a / 2
      b = b / 2
   end
   return r
end

function getTemp()
      print("Measurement start")
      sensors={}
      temps={}
      counter=0
      addr = ow.reset_search(pin)
      repeat
      tmr.wdclr()
      if (addr ~= nil) then
        crc = ow.crc8(string.sub(addr,1,7))
        if (crc == addr:byte(8)) then
          if ((addr:byte(1) == 0x10) or (addr:byte(1) == 0x28)) then
      sensor = ""
      for j = 1,7 do sensor = sensor .. string.format("%02x", addr:byte(j)) end
                print("Have sensor " .. sensor)
                sensors[counter] = sensor
                ow.reset(pin)
                ow.select(pin, addr)
                ow.write(pin, 0x44, 1)
                tmr.delay(1000 * 1000)
                present = ow.reset(pin)
                ow.select(pin, addr)
                ow.write(pin,0xBE, 1)
                data = nil
                data = string.char(ow.read(pin))
                for i = 1, 8 do data = data .. string.char(ow.read(pin)) end
                crc = ow.crc8(string.sub(data,1,8))
                if (crc == data:byte(9)) then
                   t = (data:byte(1) + data:byte(2) * 256)
         if (t > 32768) then
                    t = (bxor(t, 0xffff)) + 1
                    t = (-1) * t
                   end
         t = t * 625
                   if(addr:byte(1) == 0x10) then
                     -- we have DS18S20, the measurement must change
                     t = t * 8;  -- compensating for the 9-bit resolution only
                     t = t - 2500 + ((10000 * (data:byte(8) - data:byte(7))) / data:byte(8))
                   end
                   print("Got temp: " .. t)
                   temps[counter] = t
                end
          end
        end
      end
      addr = ow.search(pin)
      counter = counter + 1
      until(addr == nil)

    srv=net.createConnection(net.TCP, 0)
    srv:connect(8888, "192.168.11.1")
    srv:on("connection", function(conn)
                             print "We have connection"
                         end
                         )
    for i, sensorID in ipairs(sensors) do
        t1 = temps[i] / 10000
        t2 = (temps[i] >= 0 and temps[i] % 10000) or (10000 - temps[i] % 10000)
        srv:send(wifi.sta.getmac())
        print("Sending: \t" .. sensorID .. "\t" .. t1 .. "." .. string.format("%04d", t2) .. "\n")
        srv:send("\t" .. sensorID .. "\t" .. t1 .. "." .. string.format("%04d", t2) .. "\n")
    end
    srv:on("sent",function(conn)
                      print("Data sent")
                      conn:close()
                  end)
end

function checkIP()
    if wifi.sta.getip() ~= nil then
        tmr.stop(0)
        tmr.wdclr()
        print("Got IP")
        print(wifi.sta.getip())
        print("Starting Temp measurement")
        getTemp()
        tmr.alarm(0,30*1000, 1, getTemp)
    end
end

tmr.alarm(0, 2 * 1000, 1, checkIP)


The new code includes fixes for the measurement using DS18S20 (9bit resolution + compensation based on the documentation).
However, with the new firmware (0.9.4) the sending part is not working for me - I already filed a bug to this thread.