Wrap the soft PWM library

klajo · Aug 25, 2012 · 354a251 · 354a251
1 parent 5a82d6d
commit 354a251
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Showing 4 changed files with 68 additions and 2 deletions.
diff --git a/README.md b/README.md
@@ -44,6 +44,7 @@ Functionality
 * read from, write to and control pins
 * control and write to LCDs
 * shift in/out bits (untested)
+* soft PWM
 
 Caveats
 -------

diff --git a/c_src/wpi.c b/c_src/wpi.c
@@ -22,11 +22,16 @@
 #include <wiringPi.h>
 #include <lcd.h>
 #include <wiringShift.h>
+#include <softPwm.h>
+
+static ERL_NIF_TERM atom_ok;
+static ERL_NIF_TERM atom_error;
 
 static int
 load(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info)
 {
     atom_ok = enif_make_atom(env, "ok");
+    atom_error = enif_make_atom(env, "error");
     return wiringPiSetup(); // returns -1 in case of error ==> loading fails
 }
 
@@ -221,6 +226,46 @@ shift_out_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
     return atom_ok;
 }
 
+// soft PWM
+static ERL_NIF_TERM
+soft_pwm_create_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    int pin, init_value, range, result;
+    ERL_NIF_TERM atom_fail, err_code;
+    if (!enif_get_int(env, argv[0], &pin)        ||
+        !enif_get_int(env, argv[1], &init_value) ||
+        !enif_get_int(env, argv[2], &range))
+    {
+        return enif_make_badarg(env);
+    }
+    result = softPwmCreate(pin, init_value, range);
+    if (result)
+    {
+        atom_fail = enif_make_atom(env, "failed_to_init_pwm_pin");
+        err_code = enif_make_int(env, result);
+        return enif_make_tuple2(env,
+                                atom_error,
+                                enif_make_tuple2(env, atom_fail, err_code));
+    }
+    else
+    {
+        return atom_ok;
+    }
+}
+
+static ERL_NIF_TERM
+soft_pwm_write_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    int pin, value;
+    if (!enif_get_int(env, argv[0], &pin) ||
+        !enif_get_int(env, argv[1], &value))
+    {
+        return enif_make_badarg(env);
+    }
+    softPwmWrite(pin, value);
+    return atom_ok;
+}
+
 static ErlNifFunc nif_funcs[] =
     {
         // the basics: pins and stuff
@@ -238,7 +283,10 @@ static ErlNifFunc nif_funcs[] =
         {"lcd_puts_nif",            3, lcd_puts_nif},
         // shift
         {"shift_in_nif",            3, shift_in_nif},
-        {"shift_out_nif",           4, shift_out_nif}
+        {"shift_out_nif",           4, shift_out_nif},
+        // soft pwm
+        {"soft_pwm_create_nif",     3, soft_pwm_create_nif},
+        {"soft_pwm_write_nif",      2, soft_pwm_write_nif}
     };
 
 ERL_NIF_INIT(wpi, nif_funcs, load, NULL, NULL, NULL)
diff --git a/rebar.config b/rebar.config
@@ -1 +1 @@
-{port_env, [{"LDFLAGS", "$LDFLAGS -lwiringPi"}]}.
+{port_env, [{"LDFLAGS", "$LDFLAGS -lwiringPi -lpthread"}]}.
diff --git a/src/wpi.erl b/src/wpi.erl
@@ -41,6 +41,10 @@
 -export([shift_in/3]).
 -export([shift_out/4]).
 
+%% soft PWM
+-export([soft_pwm_create/3]).
+-export([soft_pwm_write/2]).
+
 -define(nif_stub,
         erlang:nif_error({nif_not_loaded, module, ?MODULE, line, ?LINE})).
 
@@ -205,3 +209,16 @@ shift_out(DataPin, ClockPin, Order, Value)
 
 shift_in_nif(_DataPin, _ClockPin, _Order)          -> ?nif_stub.
 shift_out_nif(_DataPin, _ClockPin, _Order, _Value) -> ?nif_stub.
+
+-spec soft_pwm_create(wpi_pin_number(), integer(), integer()) -> ok.
+soft_pwm_create(Pin, InitValue, Range) when is_integer(Pin),
+                                            is_integer(InitValue),
+                                            is_integer(Range) ->
+    soft_pwm_create_nif(Pin, InitValue, Range).
+
+-spec soft_pwm_write(wpi_pin_number(), integer()) -> ok.
+soft_pwm_write(Pin, Value) when is_integer(Pin), is_integer(Value) ->
+    soft_pwm_write_nif(Pin, Value).
+
+soft_pwm_create_nif(_Pin, _InitValue, _Range) -> ?nif_stub.
+soft_pwm_write_nif(_Pin, _Value)              -> ?nif_stub.