DS18B20

Info: Currently unused, soon to be discontinued.

DS18B20 Functions

This category contains functions specific to DS18B20 temperature sensors.

API Name	Brief Description
api.ds18b20GetTemp(pwrpin, datapin, address)	Returns temperature in millidegrees Celsius from DS18B20.
api.ds18b20Search(pwrpin, datapin, numdev)	Searches for DS18B20 devices on the 1-Wire bus.

api.ds18b20GetTemp(pwrpin, datapin, address)

---

api.ds18b20GetTemp(1, 2)

Returns temperature in millidegrees Celsius (m°C) from DS18B20.

Info: In case of using multiple DS18B20 sensors connected to one data pin, it’s possible to address a specific DS18B20 with its ID.

Warning: Disabled by default, requires firmware and hardware changes.

Arguments

• pwrpin (integer): Power pin number.
• datapin (integer): Data pin number.

Optional

• address (array, optional): Array of numbers used as address (8 bytes). When no array is specified, gets temperature from the first 1-Wire device.

Return

• temperature (integer): Temperature in millidegrees Celsius.

Example

-- Search all devices on the 1-Wire bus
found = api.ds18b20Search(1, 2)
-- `found` contains a table of addresses of found devices or `nil` if no device was found

-- Print count of devices found
if found then
    print("Found " .. #found .. " devices")
    -- Loop over all addresses
    for i = 1, #found, 1 do
        temp = api.ds18b20GetTemp(1, 2, found[i])
        temp = temp / 1000
        print("Teplomer #" .. i .. " " .. temp .. "C")
    end
else
    print("No devices found!")
end

-- Without addressing (one sensor = one data pin)
res1 = api.ds18b20GetTemp(1, 2) -- get temperature from sensor connected to data pin 2
print("Temperature: " .. tostring(res1) .. " mDeg.C")

api.ds18b20Search(pwrpin, datapin, numdev)

---

api.ds18b20Search(1, 2)

Searches for DS18B20 devices on the 1-Wire bus.

Arguments

• pwrpin (integer): Power pin number.
• datapin (integer): Data pin number.

Optional

• numdev (integer, optional): Number of found devices to stop the scan after.

Return

• addresses (integer): nil or array of addresses found on the specified bus.

Example

-- Find addresses of up to 3 sensors
api.ds18b20Search(1, 2, 3)