Add mgos_barometer API

src/mgos_barometer_internal.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "mgos.h"
+#include "mgos_barometer.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Barometer
+typedef bool (*mgos_barometer_mag_detect_fn)(struct mgos_barometer *dev);
+typedef bool (*mgos_barometer_mag_create_fn)(struct mgos_barometer *dev);
+typedef bool (*mgos_barometer_mag_destroy_fn)(struct mgos_barometer *dev);
+typedef bool (*mgos_barometer_mag_read_fn)(struct mgos_barometer *dev);
+
+struct mgos_barometer {
+  struct mgos_i2c *      i2c;
+  uint8_t                i2caddr;
+  enum mgos_barometer_type type;
+  bool has_thermometer;
+  bool has_barometer;
+
+  mgos_barometer_mag_detect_fn detect;
+  mgos_barometer_mag_create_fn  create;
+  mgos_barometer_mag_destroy_fn  destroy;
+  mgos_barometer_mag_read_fn   read;
+
+  void *user_data;
+
+  float pressure; // in Pascals
+  float temperature; // in Celcius
+};
+
+#ifdef __cplusplus
+}
+#endif