Initial checkin of empty MCP9808 driver

src/mgos_mcp9808.c

@@ -0,0 +1,82 @@
+/*
+ * 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.
+ */
+
+#include "mgos.h"
+#include "mgos_mcp9808_internal.h"
+#include "mgos_i2c.h"
+
+// Datasheet:
+// https://cdn-shop.adafruit.com/datasheets/MCP9808.pdf
+
+// Private functions follow
+// Private functions end
+
+// Public functions follow
+struct mgos_mcp9808 *mgos_mcp9808_create(struct mgos_i2c *i2c, uint8_t i2caddr) {
+  struct mgos_mcp9808 *sensor;
+
+  if (!i2c) return NULL;
+
+  sensor=calloc(1, sizeof(struct mgos_mcp9808));
+  if (!sensor) return NULL;
+  sensor->i2caddr=i2caddr;
+  sensor->i2c=i2c;
+  sensor->last_read_time=0;
+
+  // Check for the right chip.
+  if (false) {
+    LOG(LL_INFO, ("MCP9808 created at I2C 0x%02x", i2caddr));
+    return sensor;
+  }
+
+  LOG(LL_ERROR, ("Failed to create MCP9808 at I2C 0x%02x", i2caddr));
+  free(sensor);
+  return NULL;
+}
+
+void mgos_mcp9808_destroy(struct mgos_mcp9808 **sensor) {
+  if (!*sensor) return;
+  free (*sensor);
+  *sensor=NULL;
+  return;
+}
+
+bool mgos_mcp9808_read(struct mgos_mcp9808 *sensor) {
+  double now = mg_time();
+
+  if (!sensor || !sensor->i2c)
+    return false;
+
+  if (now - sensor->last_read_time < MGOS_MCP9808_READ_DELAY) {
+    return true;
+  }
+  // Read out sensor data here 
+  //
+  LOG(LL_DEBUG, ("temperature=%.2fC", sensor->temperature));
+  sensor->last_read_time=now;
+  return true;
+}
+
+float mgos_mcp9808_getTemperature(struct mgos_mcp9808 *sensor) {
+  if (!mgos_mcp9808_read(sensor)) return NAN;
+
+  return sensor->temperature;
+}
+
+bool mgos_mcp9808_i2c_init(void) {
+  return true;
+}
+// Public functions end