Add CCS811 driver

include/mgos_ccs811.h

@@ -0,0 +1,102 @@
+/*
+ * 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_i2c.h"
+
+#define MGOS_CCS811_READ_DELAY    (2)
+
+#ifdef __cplusplus
+extern "C" {
+  #endif
+
+struct mgos_ccs811;
+struct mgos_ccs811_stats {
+  double   last_read_time;       // value of mg_time() upon last call to _read()
+  uint32_t read;                 // calls to _read()
+  uint32_t read_success;         // successful _read()
+  uint32_t read_success_cached;  // calls to _read() which were cached
+  // Note: read_errors := read - read_success - read_success_cached
+  double   read_success_usecs;   // time spent in successful uncached _read()
+};
+
+// Drive modes
+enum mgos_ccs811_drive_mode_t {
+  CCS811_DRIVE_MODE_IDLE  = 0x00,
+  CCS811_DRIVE_MODE_1SEC  = 0x01,
+  CCS811_DRIVE_MODE_10SEC = 0x02,
+  CCS811_DRIVE_MODE_60SEC = 0x03,
+  CCS811_DRIVE_MODE_250MS = 0x04,
+};
+
+/*
+ * Initialize a CCS811 on the I2C bus `i2c` at address specified in `i2caddr`
+ * parameter (default CCS811 is on address 0x5A). The sensor will be polled for
+ * validity, upon success a new `struct mgos_ccs811` is allocated and
+ * returned. If the device could not be found, NULL is returned.
+ */
+struct mgos_ccs811 *mgos_ccs811_create(struct mgos_i2c *i2c, uint8_t i2caddr);
+
+/*
+ * Destroy the data structure associated with a CCS811 device. The reference
+ * to the pointer of the `struct mgos_ccs811` has to be provided, and upon
+ * successful destruction, its associated memory will be freed and the pointer
+ * set to NULL.
+ */
+void mgos_ccs811_destroy(struct mgos_ccs811 **sensor);
+
+/*
+ * The sensor will be polled for its temperature and humidity data. If the poll
+ * has occured in the last `MGOS_CCS811_READ_DELAY` seconds, the cached data is
+ * used (so as not to repeatedly poll the bus upon subsequent calls).
+ */
+bool mgos_ccs811_read(struct mgos_ccs811 *sensor);
+
+/*
+ * Set the drive mode of the CCS811 sensor based on the `mode` argument
+ * Returns true on success, false otherwise.
+ */
+bool mgos_ccs811_setDriveMode(struct mgos_ccs811 *sensor, enum mgos_ccs811_drive_mode_t mode);
+
+/*
+ * Retrieve the current drive mode (which will be one of `enum mgos_ccs811_drive_mode_t`
+ * values into the byte pointed to by `mode`.
+ * Returns true on success, false otherwise.
+ */
+bool mgos_ccs811_getDriveMode(struct mgos_ccs811 *sensor, uint8_t *mode);
+
+/*
+ *
+ * Returns a value on success, NAN otherwise.
+ */
+float mgos_ccs811_get_eco2(struct mgos_ccs811 *sensor);
+
+/*
+ *
+ * Returns a value on success, NAN otherwise.
+ */
+float mgos_ccs811_get_tvoc(struct mgos_ccs811 *sensor);
+
+/*
+ * Initialization function for MGOS -- currently a noop.
+ */
+bool mgos_ccs811_i2c_init(void);
+
+  #ifdef __cplusplus
+}
+#endif