Split GamePadShift from GamePad to save space on most boards.

18 files changed, 236 insertions, 78 deletions

diff --git a/ports/atmel-samd/boards/pybadge/mpconfigboard.mk b/ports/atmel-samd/boards/pybadge/mpconfigboard.mk
index 8828c17b2..63510b52a 100644
--- a/ports/atmel-samd/boards/pybadge/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/pybadge/mpconfigboard.mk
@@ -14,5 +14,7 @@ CIRCUITPY_AUDIOBUSIO = 0
 # No touch on SAMD51 yet
 CIRCUITPY_TOUCHIO = 0
 
+CIRCUITPY_GAMEPADSHIFT = 1
+
 CHIP_VARIANT = SAMD51J19A
 CHIP_FAMILY = samd51
diff --git a/py/circuitpy_defns.mk b/py/circuitpy_defns.mk
index 41c73430f..be7ff0b11 100644
--- a/py/circuitpy_defns.mk
+++ b/py/circuitpy_defns.mk
@@ -131,6 +131,10 @@ SRC_PATTERNS += frequencyio/%
 endif
 ifeq ($(CIRCUITPY_GAMEPAD),1)
 SRC_PATTERNS += gamepad/%
+	# gamepadshift depends on gamepad
+	ifeq ($(CIRCUITPY_GAMEPADSHIFT),1)
+	SRC_PATTERNS += gamepadshift/%
+	endif
 endif
 ifeq ($(CIRCUITPY_I2CSLAVE),1)
 SRC_PATTERNS += i2cslave/%
@@ -317,8 +321,9 @@ $(filter $(SRC_PATTERNS), \
 	fontio/BuiltinFont.c \
 	fontio/__init__.c \
 	gamepad/GamePad.c \
-	gamepad/GamePadShift.c \
 	gamepad/__init__.c \
+	gamepadshift/GamePadShift.c \
+	gamepadshift/__init__.c \
 	os/__init__.c \
 	random/__init__.c \
 	socket/__init__.c \
diff --git a/py/circuitpy_mpconfig.h b/py/circuitpy_mpconfig.h
index 441dd5bad..3952b5e06 100644
--- a/py/circuitpy_mpconfig.h
+++ b/py/circuitpy_mpconfig.h
@@ -322,6 +322,13 @@ extern const struct _mp_obj_module_t gamepad_module;
 #define GAMEPAD_MODULE
 #endif
 
+#if CIRCUITPY_GAMEPADSHIFT
+extern const struct _mp_obj_module_t gamepadshift_module;
+#define GAMEPADSHIFT_MODULE         { MP_OBJ_NEW_QSTR(MP_QSTR_gamepadshift),(mp_obj_t)&gamepadshift_module },
+#else
+#define GAMEPADSHIFT_MODULE
+#endif
+
 #if CIRCUITPY_I2CSLAVE
 extern const struct _mp_obj_module_t i2cslave_module;
 #define I2CSLAVE_MODULE        { MP_OBJ_NEW_QSTR(MP_QSTR_i2cslave), (mp_obj_t)&i2cslave_module },
@@ -554,6 +561,7 @@ extern const struct _mp_obj_module_t ustack_module;
     ERRNO_MODULE \
     FREQUENCYIO_MODULE \
     GAMEPAD_MODULE \
+      GAMEPADSHIFT_MODULE \
     I2CSLAVE_MODULE \
     JSON_MODULE \
     MATH_MODULE \
diff --git a/py/circuitpy_mpconfig.mk b/py/circuitpy_mpconfig.mk
index 8ea72f0bf..b436929e0 100644
--- a/py/circuitpy_mpconfig.mk
+++ b/py/circuitpy_mpconfig.mk
@@ -102,6 +102,11 @@ CIRCUITPY_GAMEPAD = $(CIRCUITPY_FULL_BUILD)
 endif
 CFLAGS += -DCIRCUITPY_GAMEPAD=$(CIRCUITPY_GAMEPAD)
 
+ifndef CIRCUITPY_GAMEPADSHIFT
+CIRCUITPY_GAMEPADSHIFT = 0
+endif
+CFLAGS += -DCIRCUITPY_GAMEPADSHIFT=$(CIRCUITPY_GAMEPADSHIFT)
+
 ifndef CIRCUITPY_I2CSLAVE
 CIRCUITPY_I2CSLAVE = $(CIRCUITPY_FULL_BUILD)
 endif
diff --git a/shared-bindings/gamepad/GamePad.c b/shared-bindings/gamepad/GamePad.c
index 8b88471ee..c80aa7f7c 100644
--- a/shared-bindings/gamepad/GamePad.c
+++ b/shared-bindings/gamepad/GamePad.c
@@ -100,7 +100,7 @@ STATIC mp_obj_t gamepad_make_new(const mp_obj_type_t *type, size_t n_args,
         mp_raise_TypeError(translate("argument num/types mismatch"));
     }
     for (size_t i = 0; i < n_args; ++i) {
-        pin_io(args[i]);
+        assert_digitalinout(args[i]);
     }
     gamepad_obj_t* gamepad_singleton = MP_STATE_VM(gamepad_singleton);
     if (!gamepad_singleton ||
@@ -110,7 +110,7 @@ STATIC mp_obj_t gamepad_make_new(const mp_obj_type_t *type, size_t n_args,
         gamepad_singleton = gc_make_long_lived(gamepad_singleton);
         MP_STATE_VM(gamepad_singleton) = gamepad_singleton;
     }
-    gamepad_init(gamepad_singleton, args, n_args);
+    common_hal_gamepad_gamepad_init(gamepad_singleton, args, n_args);
     return MP_OBJ_FROM_PTR(gamepad_singleton);
 }
 
@@ -138,7 +138,7 @@ MP_DEFINE_CONST_FUN_OBJ_1(gamepad_get_pressed_obj, gamepad_get_pressed);
 //|         Disable button scanning.
 //|
 STATIC mp_obj_t gamepad_deinit(mp_obj_t self_in) {
-    gamepad_reset();
+    common_hal_gamepad_gamepad_deinit(self_in);
     return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_1(gamepad_deinit_obj, gamepad_deinit);
diff --git a/shared-bindings/gamepad/GamePad.h b/shared-bindings/gamepad/GamePad.h
index 172c95ace..3bbad4c97 100644
--- a/shared-bindings/gamepad/GamePad.h
+++ b/shared-bindings/gamepad/GamePad.h
@@ -28,6 +28,11 @@
 #ifndef MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPAD_GAMEPAD_H
 #define MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPAD_GAMEPAD_H
 
+#include "shared-module/gamepad/GamePad.h"
+
 extern const mp_obj_type_t gamepad_type;
 
+void common_hal_gamepad_gamepad_init(gamepad_obj_t *gamepad, const mp_obj_t pins[], size_t n_pins);
+void common_hal_gamepad_gamepad_deinit(gamepad_obj_t *gamepad);
+
 #endif // MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPAD_GAMEPAD_H
diff --git a/shared-bindings/gamepad/__init__.c b/shared-bindings/gamepad/__init__.c
index 0806a142e..e61f36cc2 100644
--- a/shared-bindings/gamepad/__init__.c
+++ b/shared-bindings/gamepad/__init__.c
@@ -26,14 +26,12 @@
 #include "py/obj.h"
 #include "py/runtime.h"
 #include "py/mphal.h"
-#include "GamePad.h"
-#include "GamePadShift.h"
-#include "shared-bindings/digitalio/DigitalInOut.h"
+#include "shared-bindings/gamepad/GamePad.h"
 #include "shared-bindings/util.h"
 
 
 // Helper for validating digitalio.DigitalInOut arguments
-digitalio_digitalinout_obj_t *pin_io(mp_obj_t obj) {
+digitalio_digitalinout_obj_t *assert_digitalinout(mp_obj_t obj) {
     if (!MP_OBJ_IS_TYPE(obj, &digitalio_digitalinout_type)) {
         mp_raise_TypeError(translate("argument num/types mismatch"));
     }
@@ -55,12 +53,10 @@ digitalio_digitalinout_obj_t *pin_io(mp_obj_t obj) {
 //|     :maxdepth: 3
 //|
 //|     GamePad
-//|     GamePadShift
 //|
 STATIC const mp_rom_map_elem_t gamepad_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_gamepad) },
     { MP_OBJ_NEW_QSTR(MP_QSTR_GamePad),  MP_ROM_PTR(&gamepad_type)},
-    { MP_OBJ_NEW_QSTR(MP_QSTR_GamePadShift),  MP_ROM_PTR(&gamepadshift_type)},
 };
 STATIC MP_DEFINE_CONST_DICT(gamepad_module_globals,
         gamepad_module_globals_table);
diff --git a/shared-bindings/gamepad/__init__.h b/shared-bindings/gamepad/__init__.h
index 12e38edc4..40cf4e6de 100644
--- a/shared-bindings/gamepad/__init__.h
+++ b/shared-bindings/gamepad/__init__.h
@@ -28,6 +28,8 @@
 #ifndef MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPAD___INIT___H
 #define MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPAD___INIT___H
 
-digitalio_digitalinout_obj_t *pin_io(mp_obj_t obj);
+#include "shared-bindings/digitalio/DigitalInOut.h"
+
+digitalio_digitalinout_obj_t *assert_digitalinout(mp_obj_t obj);
 
 #endif // MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPAD___INIT___H
diff --git a/shared-bindings/gamepad/GamePadShift.c b/shared-bindings/gamepadshift/GamePadShift.c
index c24a9162a..94b71036f 100644
--- a/shared-bindings/gamepad/GamePadShift.c
+++ b/shared-bindings/gamepadshift/GamePadShift.c
@@ -28,16 +28,16 @@
 #include "py/mphal.h"
 #include "py/gc.h"
 #include "py/mpstate.h"
-#include "shared-module/gamepad/__init__.h"
-#include "shared-module/gamepad/GamePadShift.h"
+#include "shared-bindings/gamepad/__init__.h"
+#include "shared-bindings/gamepadshift/GamePadShift.h"
+#include "shared-bindings/gamepadshift/__init__.h"
+#include "shared-module/gamepadshift/GamePadShift.h"
 #include "supervisor/shared/translate.h"
-#include "GamePadShift.h"
-#include "__init__.h"
 
-//| .. currentmodule:: gamepad
+//| .. currentmodule:: gamepadshift
 //|
-//| :class:`GamePadShift` -- Scan buttons for presses
-//| =================================================
+//| :class:`GamePadShift` -- Scan buttons for presses through a shift register
+//| ===========================================================================
 //|
 //| .. class:: GamePadShift(data, clock, latch)
 //|
@@ -50,6 +50,9 @@
 //|     is called, at which point the button state is cleared, and the new
 //|     button presses start to be recorded.
 //|
+//|     Only one gamepad (`gamepad.GamePad` or `gamepadshift.GamePadShift`)
+//|     may be used at a time.
+//|
 STATIC mp_obj_t gamepadshift_make_new(const mp_obj_type_t *type, size_t n_args,
         const mp_obj_t *pos_args, mp_map_t *kw_args) {
 
@@ -63,9 +66,9 @@ STATIC mp_obj_t gamepadshift_make_new(const mp_obj_type_t *type, size_t n_args,
     mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args),
                      allowed_args, args);
 
-    digitalio_digitalinout_obj_t *data_pin = pin_io(args[ARG_data].u_obj);
-    digitalio_digitalinout_obj_t *clock_pin = pin_io(args[ARG_clock].u_obj);
-    digitalio_digitalinout_obj_t *latch_pin = pin_io(args[ARG_latch].u_obj);
+    digitalio_digitalinout_obj_t *data_pin = assert_digitalinout(args[ARG_data].u_obj);
+    digitalio_digitalinout_obj_t *clock_pin = assert_digitalinout(args[ARG_clock].u_obj);
+    digitalio_digitalinout_obj_t *latch_pin = assert_digitalinout(args[ARG_latch].u_obj);
 
     gamepadshift_obj_t* gamepad_singleton = MP_STATE_VM(gamepad_singleton);
     if (!gamepad_singleton ||
@@ -76,7 +79,7 @@ STATIC mp_obj_t gamepadshift_make_new(const mp_obj_type_t *type, size_t n_args,
         gamepad_singleton = gc_make_long_lived(gamepad_singleton);
         MP_STATE_VM(gamepad_singleton) = gamepad_singleton;
     }
-    gamepadshift_init(gamepad_singleton, data_pin, clock_pin, latch_pin);
+    common_hal_gamepadshift_gamepadshift_init(gamepad_singleton, data_pin, clock_pin, latch_pin);
     return MP_OBJ_FROM_PTR(gamepad_singleton);
 }
 
@@ -103,7 +106,7 @@ MP_DEFINE_CONST_FUN_OBJ_1(gamepadshift_get_pressed_obj, gamepadshift_get_pressed
 //|         Disable button scanning.
 //|
 STATIC mp_obj_t gamepadshift_deinit(mp_obj_t self_in) {
-    gamepad_reset();
+    common_hal_gamepadshift_gamepadshift_deinit(self_in);
     return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_1(gamepadshift_deinit_obj, gamepadshift_deinit);
diff --git a/shared-module/gamepad/GamePadShift.c b/shared-bindings/gamepadshift/GamePadShift.h
index 12083a86a..2668ec83f 100644
--- a/shared-module/gamepad/GamePadShift.c
+++ b/shared-bindings/gamepadshift/GamePadShift.h
@@ -24,20 +24,19 @@
  * THE SOFTWARE.
  */
 
-#include "shared-bindings/digitalio/DigitalInOut.h"
-#include "GamePadShift.h"
 
+#ifndef MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPADSHIFT_GAMEPADSHIFT_H
+#define MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPADSHIFT_GAMEPADSHIFT_H
 
-void gamepadshift_init(gamepadshift_obj_t *gamepadshift,
-                       digitalio_digitalinout_obj_t *data_pin,
-                       digitalio_digitalinout_obj_t *clock_pin,
-                       digitalio_digitalinout_obj_t *latch_pin) {
-    common_hal_digitalio_digitalinout_switch_to_input(data_pin, PULL_NONE);
-    gamepadshift->data_pin = data_pin;
-    common_hal_digitalio_digitalinout_switch_to_output(clock_pin, 0,
-                                                       DRIVE_MODE_PUSH_PULL);
-    gamepadshift->clock_pin = clock_pin;
-    common_hal_digitalio_digitalinout_switch_to_output(latch_pin, 1,
-                                                       DRIVE_MODE_PUSH_PULL);
-    gamepadshift->latch_pin = latch_pin;
-}
+#include "shared-module/gamepadshift/GamePadShift.h"
+
+extern const mp_obj_type_t gamepadshift_type;
+
+void common_hal_gamepadshift_gamepadshift_init(gamepadshift_obj_t *gamepadshift,
+                                                digitalio_digitalinout_obj_t *data_pin,
+                                                digitalio_digitalinout_obj_t *clock_pin,
+                                                digitalio_digitalinout_obj_t *latch_pin);
+
+void common_hal_gamepadshift_gamepadshift_deinit(gamepadshift_obj_t *gamepadshift);
+
+#endif // MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPADSHIFT_GAMEPADSHIFT_H
diff --git a/shared-bindings/gamepadshift/__init__.c b/shared-bindings/gamepadshift/__init__.c
new file mode 100644
index 000000000..2d3667726
--- /dev/null
+++ b/shared-bindings/gamepadshift/__init__.c
@@ -0,0 +1,54 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Radomir Dopieralski for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "py/obj.h"
+#include "py/runtime.h"
+#include "py/mphal.h"
+#include "shared-bindings/gamepadshift/GamePadShift.h"
+#include "shared-bindings/digitalio/DigitalInOut.h"
+#include "shared-bindings/util.h"
+
+//| :mod:`gamepadshift` --- Tracks button presses read through a shift register
+//| ===========================================================================
+//|
+//| .. module:: gamepadshift
+//|   :synopsis: Tracks button presses read through a shift register
+//|   :platform: SAMD21, SAMD51
+//|
+//| .. toctree::
+//|     :maxdepth: 3
+//|
+//|     GamePadShift
+//|
+STATIC const mp_rom_map_elem_t gamepadshift_module_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_gamepadshift) },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_GamePadShift),  MP_ROM_PTR(&gamepadshift_type)},
+};
+STATIC MP_DEFINE_CONST_DICT(gamepadshift_module_globals, gamepadshift_module_globals_table);
+
+const mp_obj_module_t gamepadshift_module = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t*)&gamepadshift_module_globals,
+};
diff --git a/shared-bindings/gamepad/GamePadShift.h b/shared-bindings/gamepadshift/__init__.h
index 68c8de876..4b4be756a 100644
--- a/shared-bindings/gamepad/GamePadShift.h
+++ b/shared-bindings/gamepadshift/__init__.h
@@ -25,9 +25,7 @@
  */
 
 
-#ifndef MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPAD_GAMEPADSHIFT_H
-#define MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPAD_GAMEPADSHIFT_H
+#ifndef MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPADSHIFT___INIT___H
+#define MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPADSHIFT___INIT___H
 
-extern const mp_obj_type_t gamepadshift_type;
-
-#endif // MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPAD_GAMEPADSHIFT_H
+#endif // MICROPY_INCLUDED_SHARED_BINDINGS_GAMEPADSHIFT___INIT___H
diff --git a/shared-module/gamepad/GamePad.c b/shared-module/gamepad/GamePad.c
index 23addb397..b3e3fabf6 100644
--- a/shared-module/gamepad/GamePad.c
+++ b/shared-module/gamepad/GamePad.c
@@ -24,10 +24,11 @@
  * THE SOFTWARE.
  */
 
+#include "py/mpstate.h"
 #include "shared-bindings/digitalio/DigitalInOut.h"
-#include "GamePad.h"
+#include "shared-bindings/gamepad/GamePad.h"
 
-void gamepad_init(gamepad_obj_t *gamepad,
+void common_hal_gamepad_gamepad_init(gamepad_obj_t *gamepad,
                   const mp_obj_t pins[], size_t n_pins) {
     for (size_t i = 0; i < 8; ++i) {
         gamepad->pins[i] = NULL;
@@ -49,3 +50,7 @@ void gamepad_init(gamepad_obj_t *gamepad,
         gamepad->pins[i] = pin;
     }
 }
+
+void common_hal_gamepad_gamepad_deinit(gamepad_obj_t *self) {
+    MP_STATE_VM(gamepad_singleton) = NULL;
+}
diff --git a/shared-module/gamepad/GamePad.h b/shared-module/gamepad/GamePad.h
index dc8a7e87a..e8bfd9c6b 100644
--- a/shared-module/gamepad/GamePad.h
+++ b/shared-module/gamepad/GamePad.h
@@ -36,10 +36,7 @@ typedef struct {
     digitalio_digitalinout_obj_t* pins[8];
     volatile uint8_t pressed;
     uint8_t pulls;
+    volatile uint8_t last;
 } gamepad_obj_t;
 
-
-void gamepad_init(gamepad_obj_t *gamepad,
-                  const mp_obj_t pins[], size_t n_pins);
-
 #endif  // MICROPY_INCLUDED_GAMEPAD_GAMEPAD_H
diff --git a/shared-module/gamepad/__init__.c b/shared-module/gamepad/__init__.c
index f92042d4b..8a4f4eae9 100644
--- a/shared-module/gamepad/__init__.c
+++ b/shared-module/gamepad/__init__.c
@@ -27,17 +27,17 @@
 #include <stdbool.h>
 
 #include "py/mpstate.h"
-#include "__init__.h"
-#include "GamePad.h"
-#include "GamePadShift.h"
+#include "shared-bindings/gamepad/__init__.h"
 #include "shared-bindings/gamepad/GamePad.h"
-#include "shared-bindings/gamepad/GamePadShift.h"
+
+#if CIRCUITPY_GAMEPADSHIFT
+#include "shared-bindings/gamepadshift/GamePadShift.h"
+#endif
 
 #include "shared-bindings/digitalio/DigitalInOut.h"
 
 
 void gamepad_tick(void) {
-    static uint8_t last = 0;
     uint8_t current = 0;
     uint8_t bit = 1;
 
@@ -59,24 +59,15 @@ void gamepad_tick(void) {
             bit <<= 1;
         }
         current ^= self->pulls;
-        self->pressed |= last & current;
-    } else if (MP_OBJ_IS_TYPE(MP_OBJ_FROM_PTR(singleton), &gamepadshift_type)) {
+        self->pressed |= self->last & current;
+        self->last = current;
+    }
+    #if CIRCUITPY_GAMEPADSHIFT
+    else if (MP_OBJ_IS_TYPE(MP_OBJ_FROM_PTR(singleton), &gamepadshift_type)) {
         // buttons connected to a shift register
-        gamepadshift_obj_t *self = singleton;
-
-        common_hal_digitalio_digitalinout_set_value(self->latch_pin, 1);
-        for (int i = 0; i < 8; ++i) {
-            common_hal_digitalio_digitalinout_set_value(self->clock_pin, 0);
-            if (common_hal_digitalio_digitalinout_get_value(self->data_pin)) {
-                current |= bit;
-            }
-            common_hal_digitalio_digitalinout_set_value(self->clock_pin, 1);
-            bit <<= 1;
-        }
-        common_hal_digitalio_digitalinout_set_value(self->latch_pin, 0);
-        self->pressed |= last & current;
+        gamepadshift_tick(singleton);
     }
-    last = current;
+    #endif
 }
 
 void gamepad_reset(void) {
diff --git a/shared-module/gamepadshift/GamePadShift.c b/shared-module/gamepadshift/GamePadShift.c
new file mode 100644
index 000000000..1dadfb9b2
--- /dev/null
+++ b/shared-module/gamepadshift/GamePadShift.c
@@ -0,0 +1,64 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Radomir Dopieralski for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/mpstate.h"
+#include "shared-bindings/digitalio/DigitalInOut.h"
+#include "shared-module/gamepadshift/GamePadShift.h"
+
+void common_hal_gamepadshift_gamepadshift_init(gamepadshift_obj_t *gamepadshift,
+                                                digitalio_digitalinout_obj_t *data_pin,
+                                                digitalio_digitalinout_obj_t *clock_pin,
+                                                digitalio_digitalinout_obj_t *latch_pin) {
+    common_hal_digitalio_digitalinout_switch_to_input(data_pin, PULL_NONE);
+    gamepadshift->data_pin = data_pin;
+    common_hal_digitalio_digitalinout_switch_to_output(clock_pin, 0,
+                                                       DRIVE_MODE_PUSH_PULL);
+    gamepadshift->clock_pin = clock_pin;
+    common_hal_digitalio_digitalinout_switch_to_output(latch_pin, 1,
+                                                       DRIVE_MODE_PUSH_PULL);
+    gamepadshift->latch_pin = latch_pin;
+}
+
+void common_hal_gamepadshift_gamepadshift_deinit(gamepadshift_obj_t *gamepadshift) {
+    MP_STATE_VM(gamepad_singleton) = NULL;
+}
+
+void gamepadshift_tick(gamepadshift_obj_t *self) {
+    uint8_t current = 0;
+    uint8_t bit = 1;
+    common_hal_digitalio_digitalinout_set_value(self->latch_pin, 1);
+    for (int i = 0; i < 8; ++i) {
+        common_hal_digitalio_digitalinout_set_value(self->clock_pin, 0);
+        if (common_hal_digitalio_digitalinout_get_value(self->data_pin)) {
+            current |= bit;
+        }
+        common_hal_digitalio_digitalinout_set_value(self->clock_pin, 1);
+        bit <<= 1;
+    }
+    common_hal_digitalio_digitalinout_set_value(self->latch_pin, 0);
+    self->pressed |= self->last & current;
+    self->last = current;
+}
diff --git a/shared-module/gamepad/GamePadShift.h b/shared-module/gamepadshift/GamePadShift.h
index 05235f318..ccbf5ca06 100644
--- a/shared-module/gamepad/GamePadShift.h
+++ b/shared-module/gamepadshift/GamePadShift.h
@@ -24,8 +24,8 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_GAMEPAD_GAMEPADSHIFT_H
-#define MICROPY_INCLUDED_GAMEPAD_GAMEPADSHIFT_H
+#ifndef MICROPY_INCLUDED_GAMEPADSHIFT_GAMEPADSHIFT_H
+#define MICROPY_INCLUDED_GAMEPADSHIFT_GAMEPADSHIFT_H
 
 #include <stdint.h>
 
@@ -37,12 +37,9 @@ typedef struct {
     digitalio_digitalinout_obj_t* clock_pin;
     digitalio_digitalinout_obj_t* latch_pin;
     volatile uint8_t pressed;
+    volatile uint8_t last;
 } gamepadshift_obj_t;
 
+void gamepadshift_tick(gamepadshift_obj_t *self);
 
-void gamepadshift_init(gamepadshift_obj_t *gamepadshift,
-                       digitalio_digitalinout_obj_t *data_pin,
-                       digitalio_digitalinout_obj_t *clock_pin,
-                       digitalio_digitalinout_obj_t *latch_pin);
-
-#endif  // MICROPY_INCLUDED_GAMEPAD_GAMEPADSHIFT_H
+#endif  // MICROPY_INCLUDED_GAMEPADSHIFT_GAMEPADSHIFT_H
diff --git a/shared-module/gamepadshift/__init__.c b/shared-module/gamepadshift/__init__.c
new file mode 100644
index 000000000..c3bb83e34
--- /dev/null
+++ b/shared-module/gamepadshift/__init__.c
@@ -0,0 +1,27 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Scott Shawcroft
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+// Nothing now.