Merge pull request #10 from atomvm/i2c-improvements

I2c improvements

Author: arpunk

examples/bh1750_example/rebar.config

@@ -5,3 +5,6 @@
 {plugins, [
     atomvm_rebar3_plugin
 ]}.
+{atomvm_rebar3_plugin, [
+    {packbeam, [prune]}
+]}.

examples/bh1750_example/src/bh1750_example.erl

@@ -37,7 +37,7 @@ start() ->
 one_time_loop(BH) ->
     case bh1750:take_reading(BH) of
         {ok, Reading} ->
-            io:format("Luminosity: ~slx\n", [to_string(Reading)]);
+            io:format("Luminosity: ~slx\n", [Reading]);
         ErrorT ->
             io:format("Error taking reading temperature: ~p~n", [ErrorT])
     end,
@@ -47,9 +47,6 @@ one_time_loop(BH) ->
 continuous_loop(BH) ->
     receive
         Reading ->
-            io:format("Luminosity: ~slx\n", [to_string(Reading)])
+            io:format("Luminosity: ~p\n", [Reading])
     end,
     continuous_loop(BH).
-
-to_string({Integral, {Fractional, _}}) ->
-    io_lib:format("~p.~p", [Integral, Fractional]).

examples/bme280_example/rebar.config

@@ -5,3 +5,6 @@
 {plugins, [
     atomvm_rebar3_plugin
 ]}.
+{atomvm_rebar3_plugin, [
+    {packbeam, [prune]}
+]}.

examples/sht3x_example/rebar.config

@@ -5,3 +5,6 @@
 {plugins, [
     atomvm_rebar3_plugin
 ]}.
+{atomvm_rebar3_plugin, [
+    {packbeam, [prune]}
+]}.

src/bh1750.erl

@@ -31,8 +31,24 @@
 
 -behaviour(gen_server).
 
--export([start/1, start/2, stop/1, take_reading/1, reset/1]).
--export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
+-export([
+    start/1,
+    start/2,
+    start_link/1,
+    start_link/2,
+    stop/1,
+    take_reading/1,
+    reset/1
+]).
+
+-export([
+    init/1,
+    handle_call/3,
+    handle_cast/2,
+    handle_info/2,
+    terminate/2,
+    code_change/3]
+).
 
 % -define(TRACE_ENABLED, true).
 -include_lib("atomvm_lib/include/trace.hrl").
@@ -119,6 +135,47 @@ start(I2CBus, Options) ->
         E -> E
     end.
 
+%%-----------------------------------------------------------------------------
+%% @param   SDAPin pin number for I2C SDA channel
+%% @param   SCLPin pin number for the I2C SCL channel
+%% @returns {ok, BH} on success, or {error, Reason}, on failure
+%% @equiv   start_link(SDAPin, SCLPin, [])
+%% @doc     Start the BH1750 driver.
+%% @end
+%%-----------------------------------------------------------------------------
+-spec start_link(I2CBus::i2c_bus:i2c_bus()) -> {ok, BH::bh()} | {error, Reason::term()}.
+start_link(I2CBus) ->
+    start_link(I2CBus, []).
+
+%%-----------------------------------------------------------------------------
+%% @param   SDAPin pin number for I2C SDA channel
+%% @param   SCLPin pin number for the I2C SCL channel
+%% @param   Options additional driver options
+%% @returns {ok, BH} on success, or {error, Reason}, on failure
+%% @doc     Start the BH1750 driver.
+%%
+%% This operation will start the BH driver.  Use the returned reference
+%% in subsequent operations, such as for taking a reading.
+%%
+%% The Options parameter may be used to fine-tune behavior of the sensor,
+%% but the default values should be sufficient for weather-station based
+%% scenarios.
+%%
+%% Notes:  The default oversampling rates for temperature, pressure, and humidity
+%% is `x4'.  A sampling rate of `ignore' is not tested.
+%%
+%% The default `mode' is `forced'.  Other modes are not tested.
+%% @end
+%%-----------------------------------------------------------------------------
+-spec start_link(I2CBus::i2c_bus:i2c_bus(), Options::options()) -> {ok, BH::bh()} | {error, Reason::term()}.
+start_link(I2CBus, Options) ->
+    case gen_server:start_link(?MODULE, {I2CBus, maybe_add_self(Options)}, []) of
+        {ok, Pid} = R ->
+            maybe_start_continuous(Pid, Options),
+            R;
+        E -> E
+    end.
+
 %% @private
 maybe_add_self(Options) ->
     case proplists:get_value(mode, Options) of
@@ -324,23 +381,13 @@ do_take_reading(State) ->
 %% @private
 to_reading(Bin, Mode, MtReg) ->
     <<Reading:16/big-unsigned>> = Bin,
-    X = multiply({1, {2, 10}}, {69, MtReg}),
+    X = 1.2 * (69 / MtReg),
     Y = case Mode of
         high2 ->
-            multiply(X, 2);
+            X * 2;
         _ -> X
     end,
-    divide(Reading, Y).
-
-%% @private
-multiply(A, B) ->
-    rational:simplify(rational:reduce(rational:multiply(A, B))).
-
-%% @private
-divide(0, _B) ->
-    {0, {0, 1}};
-divide(A, B) ->
-    rational:to_decimal(rational:reduce(rational:divide(A, B)), 2).
+    Reading / Y.
 
 %% @private
 do_start_continuous_reading(State) ->
@@ -385,13 +432,8 @@ do_powerdown(State) ->
 
 %% @private
 send_command(I2CBus, Address, Command) ->
-    % ok = i2c_bus:begin_transmission(I2CBus, Address),
-    % ok = i2c_bus:write_byte(I2CBus, Command),
-    % ok = i2c_bus:end_transmission(I2CBus).
     ?TRACE("sending command to bus ~p using address ~p command ~p ...", [I2CBus, Address, Command]),
-    ok = i2c_bus:enqueue(I2CBus, Address, [
-        fun(Port, _Address) -> ok = i2c:write_byte(Port, Command) end
-    ]).
+    i2c_bus:write_bytes(I2CBus, Address, Command).
 
 %% @private
 get_command(one_time, high) ->
@@ -410,22 +452,10 @@ get_command(continuous, low) ->
 %% @private
 get_sleep_ms(Resolution, MtReg) ->
     Base = get_sleep_ms(Resolution),
-    Sleep = multiply(Base, divide(MtReg, 69)),
-    round_sleep(Sleep).
+    Sleep = Base * (MtReg / 69),
+    erlang:round(Sleep).
 
 %% @private
 get_sleep_ms(high) -> 120;
 get_sleep_ms(high2) -> 120;
 get_sleep_ms(low) -> 16.
-
-%% @private
-round_sleep({I, {_N, _D} = F}) ->
-    I + round_sleep(F);
-round_sleep({0, _D}) ->
-    0;
-round_sleep({N, D}) ->
-    case N > (D bsr 1) of
-        true -> 1;
-        _ -> 0
-    end;
-round_sleep(I) when is_integer(I) -> I.

src/i2c_bus.erl

@@ -46,7 +46,7 @@
 -define(DEFAULT_OPTIONS, #{freq_hz => 400000}).
 
 -record(state, {
-    port
+    i2c
 }).
 
 %%-----------------------------------------------------------------------------
@@ -137,39 +137,38 @@ read_bytes(Bus, Address, Register, Count) ->
 
 %% @hidden
 init(Options) ->
-    Port = i2c:open([
-        {sda, maps:get(sda, Options)},
-        {scl, maps:get(scl, Options)},
+    I2C = i2c:open([
         {clock_speed_hz, maps:get(freq_hz, Options)}
+        | maps:to_list(Options)
     ]),
-    ?TRACE("Port opened. Options: ~p Port: ~p", [Options, Port]),
+    ?TRACE("I2C opened. Options: ~p I2C: ~p", [Options, I2C]),
     State = #state{
-        port = Port
+        i2c = I2C
     },
     {ok, State}.
 
 %% @hidden
 handle_call({enqueue, Address, Operations}, _From, State) ->
-    Reply = try_enqueue_operations(State#state.port, Address, Operations),
+    Reply = try_enqueue_operations(State#state.i2c, Address, Operations),
     {reply, Reply, State};
 handle_call({write_bytes, Address, Bytes}, _From, State) ->
-    ?TRACE("Writing bytes ~p to address ~p i2c ~p", [Bytes, Address, State#state.port]),
-    Reply = i2c:write_bytes(State#state.port, Address, Bytes),
+    ?TRACE("Writing bytes ~p to address ~p i2c ~p", [Bytes, Address, State#state.i2c]),
+    Reply = i2c:write_bytes(State#state.i2c, Address, Bytes),
     ?TRACE("Reply: ~p", [Reply]),
     {reply, Reply, State};
 handle_call({write_bytes, Address, Register, Bytes}, _From, State) ->
-    ?TRACE("Writing bytes ~p to address ~p register ~p i2c ~p", [Bytes, Address, Register, State#state.port]),
-    Reply = i2c:write_bytes(State#state.port, Address, Register, Bytes),
+    ?TRACE("Writing bytes ~p to address ~p register ~p i2c ~p", [Bytes, Address, Register, State#state.i2c]),
+    Reply = i2c:write_bytes(State#state.i2c, Address, Register, Bytes),
     ?TRACE("Reply: ~p", [Reply]),
     {reply, Reply, State};
 handle_call({read_bytes, Address, Count}, _From, State) ->
-    ?TRACE("Reading bytes off address ~p count ~p i2c ~p", [Address, Count, State#state.port]),
-    Reply = i2c:read_bytes(State#state.port, Address, Count),
+    ?TRACE("Reading bytes off address ~p count ~p i2c ~p", [Address, Count, State#state.i2c]),
+    Reply = i2c:read_bytes(State#state.i2c, Address, Count),
     ?TRACE("Reply: ~p", [Reply]),
     {reply, Reply, State};
 handle_call({read_bytes, Address, Register, Count}, _From, State) ->
-    ?TRACE("Reading bytes off address ~p register ~p count ~p i2c ~p", [Address, Register, Count, State#state.port]),
-    Reply = i2c:read_bytes(State#state.port, Address, Register, Count),
+    ?TRACE("Reading bytes off address ~p register ~p count ~p i2c ~p", [Address, Register, Count, State#state.i2c]),
+    Reply = i2c:read_bytes(State#state.i2c, Address, Register, Count),
     ?TRACE("Reply: ~p", [Reply]),
     {reply, Reply, State};
 handle_call(Request, _From, State) ->
@@ -186,7 +185,7 @@ handle_info(_Info, State) ->
 %% @hidden
 terminate(_Reason, State) ->
     io:format("Closing I2C ... ~n"),
-    i2c:close(State#state.port),
+    i2c:close(State#state.i2c),
     ok.
 
 %% @hidden
@@ -203,21 +202,23 @@ maybe_add_defaults(Options) ->
     maps:merge(?DEFAULT_OPTIONS, Options).
 
 %% @private
-try_enqueue_operations(Port, Address, Operations) ->
-    case i2c:begin_transmission(Port, Address) of
+try_enqueue_operations(I2C, Address, Operations) ->
+    ?TRACE("Enqueing on I2C ~p at address ~p", [I2C, Address]),
+    case i2c:begin_transmission(I2C, Address) of
         ok ->
             try
                 lists:foreach(
                     fun(Operation) ->
-                        Operation(Port, Address)
+                        ?TRACE("Executing on I2C ~p at address ~p", [I2C, Address]),
+                        Operation(I2C, Address)
                     end,
                     Operations
                 )
             catch
                 _:E ->
                     {error, E}
             after
-                i2c:end_transmission(Port)
+                i2c:end_transmission(I2C)
             end;
         E ->
             {error, E}

src/sht3x.erl

@@ -248,18 +248,7 @@ do_take_reading(State) ->
     %%
     {MSB, LSB} = create_measurement_command(State#state.options),
     ?TRACE("measurement_command: ~p", [{MSB, LSB}]),
-    ok = i2c_bus:enqueue(
-        I2CBus, ?SHT31_BASE_ADDR, [
-            fun(Port, _Address) ->
-                ?TRACE("writing ~p", [MSB]),
-                ok = i2c:write_byte(Port, MSB)
-            end,
-            fun(Port, _Address) ->
-                ?TRACE("writing ~p", [LSB]),
-                ok = i2c:write_byte(Port, LSB)
-            end
-        ]
-    ),
+    ok = i2c_bus:write_bytes(I2CBus, ?SHT31_BASE_ADDR, <<MSB:8, LSB:8>>),
     timer:sleep(20),
     %%
     %% Read the data in memory.