pybricks.nxtdevices.UltrasonicSensor: Implement in C.

Given the firmware size limitations on NXT, using Python wasn't going to be scalable. With the recent changes to the I2CDevice implementation, we can use instances of it for sensor classes written in C.

This reverts commit a37f46f756cd8453ff8f99193263ac68f9b5a057.
This is reverted instead of dropped so we maintain the logic to import Python classes into the C module in git history for future reference.

Author: laurensvalk

bricks/_common/sources.mk

@@ -70,6 +70,7 @@ PYBRICKS_PYBRICKS_SRC_C = $(addprefix pybricks/,\
 	nxtdevices/pb_type_nxtdevices_soundsensor.c \
 	nxtdevices/pb_type_nxtdevices_temperaturesensor.c \
 	nxtdevices/pb_type_nxtdevices_touchsensor.c \
+	nxtdevices/pb_type_nxtdevices_ultrasonicsensor.c \
 	parameters/pb_module_parameters.c \
 	parameters/pb_type_axis.c \
 	parameters/pb_type_button.c \

bricks/ev3/Makefile

@@ -2,6 +2,5 @@ PBIO_PLATFORM = ev3
 PB_MCU_FAMILY = TIAM1808
 
 PB_LIB_UMM_MALLOC = 1
-PB_FROZEN_MODULES = 1
 
 include ../_common/arm_none_eabi.mk

bricks/ev3/manifest.py

@@ -1,4 +1 @@
-# Common modules
 include("../_common/manifest.py")
-
-freeze_as_mpy("../ev3/modules", "_i2c_sensors.py")

bricks/ev3/modules/_i2c_sensors.py

@@ -13,6 +13,7 @@
 extern const mp_obj_type_t pb_type_nxtdevices_TouchSensor;
 extern const mp_obj_type_t pb_type_nxtdevices_LightSensor;
 extern const mp_obj_type_t pb_type_nxtdevices_ColorSensor;
+extern const mp_obj_type_t pb_type_nxtdevices_UltrasonicSensor;
 
 #if PYBRICKS_PY_EV3DEVDEVICES
 

pybricks/nxtdevices/nxtdevices.h

@@ -5,9 +5,6 @@
 
 #if PYBRICKS_PY_NXTDEVICES
 
-#include "py/builtin.h"
-#include "py/runtime.h"
-
 #include <pybricks/common.h>
 #include <pybricks/nxtdevices/nxtdevices.h>
 
@@ -19,6 +16,7 @@ static const mp_rom_map_elem_t nxtdevices_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_TouchSensor),       MP_ROM_PTR(&pb_type_nxtdevices_TouchSensor)      },
     { MP_ROM_QSTR(MP_QSTR_LightSensor),       MP_ROM_PTR(&pb_type_nxtdevices_LightSensor)      },
     { MP_ROM_QSTR(MP_QSTR_ColorSensor),       MP_ROM_PTR(&pb_type_nxtdevices_ColorSensor)      },
+    { MP_ROM_QSTR(MP_QSTR_UltrasonicSensor),  MP_ROM_PTR(&pb_type_nxtdevices_UltrasonicSensor) },
     #if PYBRICKS_PY_EV3DEVDEVICES
     { MP_ROM_QSTR(MP_QSTR_EnergyMeter),       MP_ROM_PTR(&pb_type_nxtdevices_EnergyMeter)      },
     { MP_ROM_QSTR(MP_QSTR_SoundSensor),       MP_ROM_PTR(&pb_type_nxtdevices_SoundSensor)      },
@@ -32,21 +30,8 @@ const mp_obj_module_t pb_module_nxtdevices = {
     .globals = (mp_obj_dict_t *)&pb_module_nxtdevices_globals,
 };
 
-void pb_module_nxtdevices_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
-    // Support only load.
-    if (dest[0] != MP_OBJ_NULL) {
-        return;
-    }
-
-    // Load from the frozen _i2c_sensors module.
-    const mp_obj_t import_args[] = { MP_OBJ_NEW_QSTR(MP_QSTR__i2c_sensors) };
-    mp_obj_t module = mp_builtin___import__(MP_ARRAY_SIZE(import_args), import_args);
-    mp_load_method_maybe(module, attr, dest);
-}
-
 #if !MICROPY_MODULE_BUILTIN_SUBPACKAGES
 MP_REGISTER_MODULE(MP_QSTR_pybricks_dot_nxtdevices, pb_module_nxtdevices);
 #endif
-MP_REGISTER_MODULE_DELEGATION(pb_module_nxtdevices, pb_module_nxtdevices_attr);
 
 #endif // PYBRICKS_PY_NXTDEVICES

pybricks/nxtdevices/pb_module_nxtdevices.c

@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2018-2025 The Pybricks Authors
+
+#include "py/mpconfig.h"
+
+#if PYBRICKS_PY_NXTDEVICES
+
+#include "py/mphal.h"
+
+#include <pbdrv/i2c.h>
+#include <pbio/port_interface.h>
+
+#include <pybricks/common.h>
+#include <pybricks/iodevices/iodevices.h>
+#include <pybricks/parameters.h>
+
+#include <pybricks/util_mp/pb_kwarg_helper.h>
+#include <pybricks/util_mp/pb_obj_helper.h>
+#include <pybricks/util_pb/pb_error.h>
+
+// pybricks.nxtdevices.UltrasonicSensor class object
+typedef struct _nxtdevices_UltrasonicSensor_obj_t {
+    mp_obj_base_t base;
+    mp_obj_t *i2c_device_obj;
+} nxtdevices_UltrasonicSensor_obj_t;
+
+// pybricks.nxtdevices.UltrasonicSensor.__init__
+static mp_obj_t nxtdevices_UltrasonicSensor_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    PB_PARSE_ARGS_CLASS(n_args, n_kw, args,
+        PB_ARG_REQUIRED(port));
+
+    nxtdevices_UltrasonicSensor_obj_t *self = mp_obj_malloc(nxtdevices_UltrasonicSensor_obj_t, type);
+    self->i2c_device_obj = pb_type_i2c_device_make_new(port_in, mp_obj_new_int(0x01), false, true, true);
+
+    // NXT Ultrasonic Sensor appears to need some time after initializing I2C pins before it can receive data.
+    mp_hal_delay_ms(100);
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+static mp_obj_t map_distance(const uint8_t *data, size_t len) {
+    return mp_obj_new_int(data[0] * 10);
+}
+
+// pybricks.nxtdevices.UltrasonicSensor.distance
+static mp_obj_t nxtdevices_UltrasonicSensor_distance(mp_obj_t self_in) {
+    nxtdevices_UltrasonicSensor_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    const uint8_t write_data[] = { 0x42 };
+    return pb_type_i2c_device_start_operation(self->i2c_device_obj, write_data, MP_ARRAY_SIZE(write_data), 1, map_distance);
+}
+static MP_DEFINE_CONST_FUN_OBJ_1(nxtdevices_UltrasonicSensor_distance_obj, nxtdevices_UltrasonicSensor_distance);
+
+// dir(pybricks.nxtdevices.UltrasonicSensor)
+static const mp_rom_map_elem_t nxtdevices_UltrasonicSensor_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_distance), MP_ROM_PTR(&nxtdevices_UltrasonicSensor_distance_obj) },
+};
+static MP_DEFINE_CONST_DICT(nxtdevices_UltrasonicSensor_locals_dict, nxtdevices_UltrasonicSensor_locals_dict_table);
+
+// type(pybricks.nxtdevices.UltrasonicSensor)
+MP_DEFINE_CONST_OBJ_TYPE(pb_type_nxtdevices_UltrasonicSensor,
+    MP_QSTR_UltrasonicSensor,
+    MP_TYPE_FLAG_NONE,
+    make_new, nxtdevices_UltrasonicSensor_make_new,
+    locals_dict, &nxtdevices_UltrasonicSensor_locals_dict);
+
+#endif // PYBRICKS_PY_NXTDEVICES