Add: Temperature Measurement

dev.fish

@@ -0,0 +1,15 @@
+#!/usr/bin/env fish
+
+
+set -gx MIX_TARGET "host"
+set -gx NERVES_NETWORK_SSID "not used"
+set -gx NERVES_NETWORK_PSK "not used"
+set -gx MIX_ENV "dev"
+set -gx MIX_HOST "0.0.0.0"
+set -gx MIX_PORT 4000
+set -gx PORT 4000
+
+
+
+
+

ui/assets/js/leds.js

@@ -39,4 +39,9 @@ channel.on("button-released", payload => {
   $("#push-button-1").html("Button 1 released")
 })
 
+channel.on("temperature", payload => {
+  console.log("Temperature Measurement received", payload)
+  $("#temperature").html(`${payload.celcius} ˚C`)
+})
+
 

ui/lib/ui/application.ex

@@ -12,7 +12,8 @@ defmodule Ui.Application do
       supervisor(UiWeb.Endpoint, []),
       # Start your own worker by calling: Ui.Worker.start_link(arg1, arg2, arg3)
       # worker(Ui.Worker, [arg1, arg2, arg3]),
-      worker(Ui.SwitchListener, [])
+      worker(Ui.SwitchListener, []),
+      worker(Ui.Temperature, [])
     ]
 
     # See https://hexdocs.pm/elixir/Supervisor.html

ui/lib/ui/switch_listener.ex

@@ -85,4 +85,12 @@ defmodule Ui.SwitchListener do
     end)
   end
 
+  defp read_sensor(pid, channel) do
+    {channel_value, _} = Integer.parse("#{channel + 40}", 16)
+    I2c.write(pid, <<channel_value>>)
+    I2c.read(pid, 1)
+    <<value>> = I2c.read(pid, 1)
+    value
+  end
+
 end

ui/lib/ui/temperatur.ex

@@ -0,0 +1,44 @@
+defmodule Ui.Temperature do
+
+  alias ElixirALE.I2C
+
+  def start_link() do
+    if System.get_env("MIX_TARGET") != "host" do
+      {:ok, sensors} = I2C.start_link("i2c-1", 0x48)
+      spawn(fn -> loop(%{sensors: sensors}) end)
+    else
+      spawn(fn -> loop(%{sensors: -1}) end)
+    end
+    {:ok, self()}
+  end
+
+  def loop(%{sensors: sensors} = state) do
+    celcius = read_celcius(sensors,0)
+    UiWeb.Endpoint.broadcast("nerves:lobby", "temperature", %{ celcius: celcius })
+    :timer.sleep(1000)
+    loop(state)
+  end
+
+  defp read_celcius(sensors,register) do
+    advalue = read_sensor(sensors,register)
+    volt = advalue*3.3/255.0;
+
+    rt = 10*volt / (3.3-volt)
+    temp_k = 1/(1/(273.15+25) + :math.log(rt/10)/3950)
+    temp_c = temp_k - 273.15
+    to_string(:io_lib.format("~6.2f~n", [temp_c]))
+  end
+
+   defp read_sensor(pid, channel) when pid == -1 do
+     channel_value = Enum.random((0..255))
+   end
+   defp read_sensor(pid, channel) do
+    {channel_value, _} = Integer.parse("#{channel + 40}", 16)
+    I2C.write(pid, <<channel_value>>)
+    I2C.read(pid, 1)
+    <<value>> = I2C.read(pid, 1)
+    value
+  end
+
+
+end

ui/lib/ui_web/templates/leds/index.html.eex

@@ -47,6 +47,8 @@ PUSH-BUTTON:
         <div data-led="red" class="led-button">Red <span id="red-led"></span></div>
         <div data-led="off" class="led-button">All Off</div>
         <div id="push-button-1" class="push-button">Push Button 1 released</div>
+        <hr>
+        <h1 id="temperature"></h1>
       </div>
     </div>
   </div>