Add i2c.init to change the pins and frequency

docs/i2c.rst

@@ -21,6 +21,16 @@ should be described separately in that device's documentation.
 Functions
 =========
 
+.. py:function:: init(freq=100000, sda=pin20, scl=pin19)
+
+    Re-initialize peripheral with the specified clock frequency ``freq`` on the
+    specified ``sda`` and ``scl`` pins.
+
+    .. warning::
+
+        Changing the I²C pins from defaults will make the accelerometer and
+        compass stop working, as they are connected internally to those pins.
+
 
 .. py:function:: read(addr, n, repeat=False)
 

inc/genhdr/qstrdefs.generated.h

@@ -510,6 +510,9 @@ QDEF(MP_QSTR_addr, (const byte*)"\xb6\x04" "addr")
 QDEF(MP_QSTR_n, (const byte*)"\xcb\x01" "n")
 QDEF(MP_QSTR_buf, (const byte*)"\x74\x03" "buf")
 QDEF(MP_QSTR_repeat, (const byte*)"\xf2\x06" "repeat")
+QDEF(MP_QSTR_freq, (const byte*)"\xe5\x04" "freq")
+QDEF(MP_QSTR_sda, (const byte*)"\x53\x03" "sda")
+QDEF(MP_QSTR_scl, (const byte*)"\xf9\x03" "scl")
 QDEF(MP_QSTR_music, (const byte*)"\x04\x05" "music")
 QDEF(MP_QSTR_frequency, (const byte*)"\xa1\x09" "frequency")
 QDEF(MP_QSTR_duration, (const byte*)"\x7b\x08" "duration")

inc/microbit/modmicrobit.h

@@ -190,6 +190,7 @@ MP_DECLARE_CONST_FUN_OBJ(microbit_pin_write_analog_obj);
 MP_DECLARE_CONST_FUN_OBJ(microbit_pin_is_touched_obj);
 MP_DECLARE_CONST_FUN_OBJ(microbit_pin_set_analog_period_obj);
 MP_DECLARE_CONST_FUN_OBJ(microbit_pin_set_analog_period_microseconds_obj);
+MP_DECLARE_CONST_FUN_OBJ(microbit_i2c_init_obj);
 MP_DECLARE_CONST_FUN_OBJ(microbit_i2c_read_obj);
 MP_DECLARE_CONST_FUN_OBJ(microbit_i2c_write_obj);
 MP_DECLARE_CONST_FUN_OBJ(microbit_image_width_obj);

inc/microbit/qstrdefsport.h

@@ -203,6 +203,9 @@ Q(addr)
 Q(n)
 Q(buf)
 Q(repeat)
+Q(freq)
+Q(sda)
+Q(scl)
 
 Q(music)
 Q(frequency)

source/microbit/microbiti2c.cpp

@@ -25,17 +25,62 @@
  */
 
 #include "MicroBit.h"
+#include "i2c_api.h"
+
+
+class mp_I2C : public MicroBitI2C {
+    public:
+        void set_pins(PinName sda, PinName scl);
+};
+
+void mp_I2C::set_pins(PinName sda, PinName scl) {
+    _i2c.sda = sda;
+    _i2c.scl = scl;
+}
+
 
 extern "C" {
 
 #include "py/runtime.h"
 #include "modmicrobit.h"
+#include "microbitobj.h"
+
 
 typedef struct _microbit_i2c_obj_t {
     mp_obj_base_t base;
     MicroBitI2C *i2c;
 } microbit_i2c_obj_t;
 
+STATIC mp_obj_t microbit_i2c_init(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_freq, MP_ARG_INT, {.u_int = 100000} },
+        { MP_QSTR_sda, MP_ARG_OBJ, {.u_obj = mp_const_none } },
+        { MP_QSTR_scl, MP_ARG_OBJ, {.u_obj = mp_const_none } },
+    };
+
+    // parse args
+    microbit_i2c_obj_t *self = (microbit_i2c_obj_t*)pos_args[0];
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+
+    PinName p_sda = MICROBIT_PIN_SDA;
+    PinName p_scl = MICROBIT_PIN_SCL;
+
+    if (args[1].u_obj != mp_const_none) {
+        p_sda = microbit_obj_get_pin_name(args[1].u_obj);
+    }
+    if (args[2].u_obj != mp_const_none) {
+        p_scl = microbit_obj_get_pin_name(args[2].u_obj);
+    }
+    ((mp_I2C*)self->i2c)->set_pins(p_sda, p_scl);
+
+    self->i2c->frequency(args[0].u_int); // also does i2c_reset()
+
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_KW(microbit_i2c_init_obj, 1, microbit_i2c_init);
+
 STATIC mp_obj_t microbit_i2c_read(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_addr,     MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
@@ -85,6 +130,7 @@ STATIC mp_obj_t microbit_i2c_write(mp_uint_t n_args, const mp_obj_t *pos_args, m
 MP_DEFINE_CONST_FUN_OBJ_KW(microbit_i2c_write_obj, 1, microbit_i2c_write);
 
 STATIC const mp_map_elem_t microbit_i2c_locals_dict_table[] = {
+    { MP_OBJ_NEW_QSTR(MP_QSTR_init), (mp_obj_t)&microbit_i2c_init_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_read), (mp_obj_t)&microbit_i2c_read_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_write), (mp_obj_t)&microbit_i2c_write_obj },
 };