feat(max86150): MAX86150 Pycardium API

preload/apps/spo2/__init__.py

+import max86150
+import display
+
+
+class SPO2:
+    def __init__(self):
+        self.sensor = None
+        self.RATE = 128
+        self.HISTORY_MAX = self.RATE * 4
+        self.history = []
+        self.update_screen = 0
+        self.disp = display.open()
+        self.DRAW_AFTER_SAMPLES = 5
+        self.histogram_offset = 0
+        self.WIDTH = 160
+        self.SCALE_FACTOR = 30
+        self.OFFSET_Y = 49
+        self.COLOR_BACKGROUND = [0, 0, 0]
+        self.avg = [0] * 10
+        self.avg_pos = 0
+        self.last_sample = 0.0
+        self.filtered_value = 0.0
+
+    def open(self):
+        def callback(datasets):
+            self.update_screen += len(datasets)
+
+            self.update_history(datasets)
+
+            # don't update on every callback
+            if self.update_screen >= self.DRAW_AFTER_SAMPLES:
+                self.draw_histogram()
+
+        self.sensor = max86150.MAX86150(callback)
+        while True:
+            pass
+
+    def update_history(self, datasets):
+        for val in datasets:
+            # get red value (first in tuple)
+            self.avg[self.avg_pos] = val[0]
+            if self.avg_pos < 9:
+                self.avg_pos += 1
+            else:
+                self.avg_pos = 0
+
+            avg_data = sum(self.avg) / 10
+            # DC offset removal
+            self.filtered_value = 0.9 * (
+                self.filtered_value + avg_data - self.last_sample
+            )
+            self.last_sample = avg_data
+            self.history.append(self.filtered_value)
+
+        # trim old elements
+        self.history = self.history[-self.HISTORY_MAX :]
+
+    def draw_histogram(self):
+        self.disp.clear(self.COLOR_BACKGROUND)
+
+        # offset in pause_histogram mode
+        window_end = len(self.history) - self.histogram_offset
+        s_start = max(0, window_end - (self.RATE * 2))
+        s_end = max(0, window_end)
+        s_draw = max(0, s_end - self.WIDTH)
+
+        # get max value and calc scale
+        value_max = max(abs(x) for x in self.history[s_start:s_end])
+        scale = self.SCALE_FACTOR / (value_max if value_max > 0 else 1)
+
+        # draw histogram
+        draw_points = (
+            int(x * scale + self.OFFSET_Y) for x in self.history[s_draw:s_end]
+        )
+
+        prev = next(draw_points)
+        for x, value in enumerate(draw_points):
+            self.disp.line(x, prev, x + 1, value)
+            prev = value
+
+        self.disp.update()
+        self.update_screen = 0
+
+    def close(self):
+        if self.self is not None:
+            self.sensor.close()
+            self.sensor = None
+
+
+if __name__ == "__main__":
+    sensor = SPO2()
+    try:
+        sensor.open()
+    except KeyboardInterrupt as e:
+        sensor.close()
+        raise e

preload/apps/spo2/metadata.json

+{"name":"SPO2","description":"A simple oximetetry monitor.","category":"hardware","author":"card10 contributors","revision":-1,"source":"preload"}

pycardium/meson.build

@@ -9,6 +9,7 @@ modsrc = files(
   'modules/interrupt.c',
   'modules/light_sensor.c',
   'modules/max30001-sys.c',
+  'modules/max86150.c',
   'modules/os.c',
   'modules/personal_state.c',
   'modules/power.c',

pycardium/modules/interrupt.c

@@ -97,6 +97,8 @@ static const mp_rom_map_elem_t interrupt_module_globals_table[] = {
 	  MP_OBJ_NEW_SMALL_INT(EPIC_INT_BHI160_GYROSCOPE) },
 	{ MP_ROM_QSTR(MP_QSTR_MAX30001_ECG),
 	  MP_OBJ_NEW_SMALL_INT(EPIC_INT_MAX30001_ECG) },
+	{ MP_ROM_QSTR(MP_QSTR_MAX86150),
+	  MP_OBJ_NEW_SMALL_INT(EPIC_INT_MAX86150) },
 
 };
 static MP_DEFINE_CONST_DICT(

pycardium/modules/max86150.c

+#include "py/obj.h"
+#include "py/objlist.h"
+#include "py/runtime.h"
+#include "py/builtin.h"
+#include "api/common.h"
+#include "mphalport.h"
+
+#include "epicardium.h"
+
+STATIC mp_obj_t mp_max86150_enable_sensor(size_t n_args, const mp_obj_t *args)
+{
+	struct max86150_sensor_config cfg = { 0 };
+	cfg.sample_buffer_len             = mp_obj_get_int(args[0]);
+	cfg.ppg_sample_rate               = mp_obj_get_int(args[1]);
+
+	int stream_id = epic_max86150_enable_sensor(&cfg, sizeof(cfg));
+
+	if (stream_id < 0) {
+		mp_raise_OSError(-stream_id);
+	}
+
+	return MP_OBJ_NEW_SMALL_INT(stream_id);
+}
+
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(
+	mp_max86150_enable_sensor_obj, 2, 2, mp_max86150_enable_sensor
+);
+
+STATIC mp_obj_t mp_max86150_read_sensor(mp_obj_t stream_id_in)
+{
+	struct max86150_sensor_data buf[256];
+	int stream_id = mp_obj_get_int(stream_id_in);
+
+	int n = epic_stream_read(stream_id, buf, sizeof(buf));
+
+	mp_obj_list_t *list = mp_obj_new_list(0, NULL);
+	for (int i = 0; i < n; i++) {
+		mp_obj_t tuple[3];
+
+		tuple[0] = mp_obj_new_int(buf[i].red);
+		tuple[1] = mp_obj_new_int(buf[i].ir);
+		tuple[2] = mp_obj_new_int(buf[i].ecg);
+
+		mp_obj_list_append(list, mp_obj_new_tuple(3, tuple));
+	}
+
+	return MP_OBJ_FROM_PTR(list);
+}
+
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(
+	mp_max86150_read_sensor_obj, mp_max86150_read_sensor
+);
+
+STATIC mp_obj_t mp_max86150_disable_sensor(void)
+{
+	int ret = epic_max86150_disable_sensor();
+
+	if (ret != 0) {
+		mp_raise_OSError(-ret);
+	}
+
+	return mp_const_none;
+}
+
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(
+	mp_max86150_disable_sensor_obj, mp_max86150_disable_sensor
+);
+
+STATIC const mp_rom_map_elem_t max86150_module_globals_table[] = {
+	{ MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_sys_max86150) },
+	{ MP_ROM_QSTR(MP_QSTR_enable_sensor),
+	  MP_ROM_PTR(&mp_max86150_enable_sensor_obj) },
+	{ MP_ROM_QSTR(MP_QSTR_read_sensor),
+	  MP_ROM_PTR(&mp_max86150_read_sensor_obj) },
+	{ MP_ROM_QSTR(MP_QSTR_disable_sensor),
+	  MP_ROM_PTR(&mp_max86150_disable_sensor_obj) },
+};
+STATIC MP_DEFINE_CONST_DICT(
+	max86150_module_globals, max86150_module_globals_table
+);
+
+const mp_obj_module_t max86150_module = {
+	.base    = { &mp_type_module },
+	.globals = (mp_obj_dict_t *)&max86150_module_globals,
+};
+
+/* clang-format off */
+/* Register the module to make it available in Python */
+MP_REGISTER_MODULE(MP_QSTR_sys_max86150, max86150_module, MODULE_MAX86150_ENABLED);

pycardium/modules/py/max86150.py

+import sys_max86150
+import uerrno
+import interrupt
+
+
+class MAX86150:
+    """
+    The MAX86150 class provides a stram interface to the MAX86150 PPG and ECG.
+
+    .. code-block:: python
+
+        import MAX86150
+        m = max86150.MAX86150()
+        m.read()
+        m.close()
+    """
+
+    def __init__(self, callback=None, sample_buffer_len=128, sample_rate=200):
+        """
+        Initializes the MAX86150 (if it is not already running).
+
+        :param callback: If not None: A callback which is called with the data when ever new data is available
+
+        """
+        self.active = False
+        self.stream_id = -uerrno.ENODEV
+        self.interrupt_id = interrupt.MAX86150
+        self._callback = callback
+        self.sample_rate = sample_rate
+        self.sample_buffer_len = sample_buffer_len
+        self.enable_sensor()
+
+    def enable_sensor(self):
+        """
+        Enables the sensor. Automatically called by __init__.
+        """
+        interrupt.disable_callback(self.interrupt_id)
+        interrupt.set_callback(self.interrupt_id, self._interrupt)
+        self.stream_id = sys_max86150.enable_sensor(
+            self.sample_buffer_len, self.sample_rate
+        )
+
+        self.active = True
+
+        if self._callback:
+            interrupt.enable_callback(self.interrupt_id)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, _et, _ev, _t):
+        self.close()
+
+    def close(self):
+        """
+        Close the currently open connection to the sensor.
+        """
+
+        if self.active:
+            self.active = False
+            sys_max86150.disable_sensor()
+
+            interrupt.disable_callback(self.interrupt_id)
+            interrupt.set_callback(self.interrupt_id, None)
+
+    def read(self):
+        """
+        Read as many samples (signed integer) as currently available.
+        """
+        assert self.active, "Sensor is inactive"
+        return sys_max86150.read_sensor(self.stream_id)
+
+    def _interrupt(self, _):
+        if self.active:
+            data = self.read()
+            if self._callback:
+                self._callback(data)

pycardium/modules/py/meson.build

@@ -7,6 +7,7 @@ python_modules = files(
   'ledfx.py',
   'leds.py',
   'max30001.py',
+  'max86150.py',
   'pride.py',
   'simple_menu.py',
 

pycardium/modules/qstrdefs.h

@@ -181,7 +181,9 @@ Q(CHAOS)
 Q(COMMUNICATION)
 Q(CAMP)
 
+/* required for interrupts */
 Q(MAX30001_ECG)
+Q(MAX86150)
 
 /* ws2812 */
 Q(ws2812)

pycardium/mpconfigport.h

@@ -49,6 +49,7 @@ int mp_hal_trng_read_int(void);
 
 /* Modules */
 #define MODULE_BHI160_ENABLED               (1)
+#define MODULE_MAX86150_ENABLED             (1)
 #define MODULE_BME680_ENABLED               (1)
 #define MODULE_BUTTONS_ENABLED              (1)
 #define MODULE_DISPLAY_ENABLED              (1)