Add a module with reading temperature example

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.

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.