nodemcu-firmware/lua_modules/ds18b20

DS18B20 Module

Require

ds18b20 = require("ds18b20")

Release

ds18b20 = nil
package.loaded["ds18b20"]=nil

readTemp()

Scans the bus for DS18B20 sensors, starts a readout (conversion) for all sensors and calls a callback function when all temperatures are available. Powered sensors are read at once first. Parasite-powered sensors are read one by one. The first parasite-powered sensor is read together with all powered sensors.

The module requires ow module.

The also module uses encoder module for printing debug information with more readable representation of sensor address (encoder.toHex()).

Syntax

readTemp(callback, pin)

Parameters

• callback function that receives all results when all conversions finish. The callback function has one parameter - an array addressed by sensor addresses and a value of the temperature (string for integer version).
• pin pin of the one-wire bus. If nil, GPIO0 (3) is used.

Returns

nil

Example

t = require("ds18b20")
pin = 3 -- gpio0 = 3, gpio2 = 4

function readout(temp)
  for addr, temp in pairs(temp) do
    print(string.format("Sensor %s: %s 'C", encoder.toHex(addr), temp))
  end

  -- Module can be released when it is no longer needed
  t = nil
  package.loaded["ds18b20"]=nil
end

-- t:readTemp(readout) -- default pin value is 3
t:readTemp(readout, pin)
if t.sens then
  print("Total number of DS18B20 sensors: "..table.getn(t.sens))
  for i, s in ipairs(t.sens) do
    -- print(string.format("  sensor #%d address: %s%s", i, s.addr, s.parasite == 1 and " (parasite)" or ""))
    print(string.format("  sensor #%d address: %s%s",  i, encoder.toHex(s.addr), s.parasite == 1 and " (parasite)" or "")) -- readable address with Hex encoding is preferred when encoder module is available
  end
end