From 2f22c1faf44d3d93bb3146ff605d20c9d38459b8 Mon Sep 17 00:00:00 2001
From: zofpolkowska <zofpolkowska@gmail.com>
Date: Tue, 5 Feb 2019 15:30:41 +0100
Subject: [PATCH] Add a module with reading temperature example

---
 src/rolnik_device.erl  | 36 +++++++++++++++++++++++++++++++++
 src/rolnik_example.erl | 46 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)
 create mode 100644 src/rolnik_device.erl
 create mode 100644 src/rolnik_example.erl

diff --git a/src/rolnik_device.erl b/src/rolnik_device.erl
new file mode 100644
index 0000000..dffce6b
--- /dev/null
+++ b/src/rolnik_device.erl
@@ -0,0 +1,36 @@
+% @doc
+% @end
+-module(rolnik_device).
+
+% API
+% ds18b20 termometer - connected via one wire
+-export([read_temperature_onewire/1, device_id_onewire/0]).
+% pmod hygro - connected via i2c
+-export([read_temperature_i2c/0, read_humidity_i2c/0]).
+
+
+%--- API -----------------------------------------------------------------------
+
+-spec device_id_onewire() -> [binary()].
+device_id_onewire() ->
+    grisp_onewire:transaction(fun() -> grisp_onewire:search() end).
+
+-spec read_temperature_onewire(ID :: binary()) -> float().
+read_temperature_onewire(ID) ->
+    %% ds18b20 is a digital thermomether
+    onewire_ds18b20:convert(ID, 500),
+    onewire_ds18b20:temp(ID).
+
+read_temperature_i2c() ->
+    grisp_i2c:msgs([16#40, {write, <<16#00>>}]),
+    timer:sleep(20),
+    T = grisp_i2c:msgs([16#40, {read, 2, 16#0800}]),
+    <<Temp:14/unsigned-big,_:2>> = T,
+    (Temp / 16384) * 165 - 40.
+
+read_humidity_i2c() ->
+    grisp_i2c:msgs([16#40, {write, <<16#01>>}]),
+    timer:sleep(20),
+    H = grisp_i2c:msgs([16#40, {read, 2, 16#0800}]),
+    <<Hum:14/unsigned-big,_:2>> = H,
+    (Hum / 16384) * 100.
diff --git a/src/rolnik_example.erl b/src/rolnik_example.erl
new file mode 100644
index 0000000..8dc58c2
--- /dev/null
+++ b/src/rolnik_example.erl
@@ -0,0 +1,46 @@
+% @doc
+% @end
+-module(rolnik_device).
+
+-import(rolnik_device, [device_id_onewire/0,
+                        read_temperature_onewire/1]).
+
+% API
+-export([init/0]).
+
+
+%--- API -----------------------------------------------------------------------
+
+init() ->
+    %% grisp_onewire:search/0 returns a list of IDs of devices connected via one wire,
+    %% provided example assumes there is only one slave connected
+    case device_id_onewire() of
+        [ID] ->
+            InitTemp = read_temperature_onewire(ID),
+            loop(ID, InitTemp);
+        _ ->
+            grisp_led:color(1, blue),
+            grisp_led:color(2, blue)
+    end.
+
+
+%--- Internal ------------------------------------------------------------------
+
+loop(ID, Temp) ->
+    timer:sleep(1000),
+    try read_temperature_onewire(ID) of
+        NewTemp  ->
+            case abs(NewTemp - Temp) of
+                Dif when Dif < 0.5 ->
+                    grisp_led:color(1, green),
+                    grisp_led:color(2, green);
+                _ ->
+                    grisp_led:color(1, red),
+                    grisp_led:color(2, red)
+            end,
+            loop(ID, NewTemp)
+    catch
+        _:_ ->
+            grisp_led:flash(1, red, 500),
+            grisp_led:flash(2, yellow, 500)
+    end.