Add MPL3115 driver; It's a bit slow (takes ~1s for DataReady to be set), should take a look

src/main.c

@@ -215,8 +215,8 @@ int main() {
     mgos_mpu9250_set_magnetometer_speed(mpu9250, MAG_100_HZ);
   }
   */
-  if (!(baro=mgos_barometer_create_i2c(i2c, 0x60, BARO_MPL115))) {
-    LOG(LL_ERROR, ("Cannot create MPL115 barometer"));
+  if (!(baro=mgos_barometer_create_i2c(i2c, 0x60, BARO_MPL3115))) {
+    LOG(LL_ERROR, ("Cannot create barometer"));
   } else {
     mgos_barometer_set_cache_ttl(baro, 0);
   }

src/mgos_barometer.c

@@ -47,22 +47,31 @@ struct mgos_barometer *mgos_barometer_create_i2c(struct mgos_i2c *i2c, uint8_t i
       sensor->detect = mgos_barometer_mpl3115_detect;
       sensor->create = mgos_barometer_mpl3115_create;
       sensor->read = mgos_barometer_mpl3115_read;
-      sensor->destroy = mgos_barometer_mpl3115_destroy;
+      break;
     default:
       LOG(LL_ERROR, ("Unknown mgos_barometer_type %d", type));
       free(sensor);
       return NULL;
   }
-  if ((sensor->detect) && !sensor->detect(sensor)) {
-    LOG(LL_ERROR, ("Could not detect mgos_barometer_type %d at I2C 0x%02x", type, i2caddr));
-    free(sensor);
-    return NULL;
+  sensor->type=type;
+  if (sensor->detect) {
+    if (!sensor->detect(sensor)) {
+      LOG(LL_ERROR, ("Could not detect mgos_barometer_type %d at I2C 0x%02x", type, i2caddr));
+      free(sensor);
+      return NULL;
+    } else {
+      LOG(LL_DEBUG, ("Successfully detected mgos_barometer_type %d at I2C 0x%02x", type, i2caddr));
+    }
   }
 
-  if ((sensor->create) && !sensor->create(sensor)) {
-    LOG(LL_ERROR, ("Could not create mgos_barometer_type %d at I2C 0x%02x", type, i2caddr));
-    free(sensor);
-    return NULL;
+  if (sensor->create) {
+    if (!sensor->create(sensor)) {
+      LOG(LL_ERROR, ("Could not create mgos_barometer_type %d at I2C 0x%02x", type, i2caddr));
+      free(sensor);
+      return NULL;
+    } else {
+      LOG(LL_DEBUG, ("Successfully created mgos_barometer_type %d at I2C 0x%02x", type, i2caddr));
+    }
   }
 
   return sensor;

src/mgos_barometer_mpl3115.c

@@ -1,21 +1,97 @@
-#include "mgos_barometer_mpl115.h"
+#include "mgos_barometer_mpl3115.h"
 #include "mgos_i2c.h"
 
 // Datasheet:
 // https://cdn-shop.adafruit.com/datasheets/1893_datasheet.pdf
 
 bool mgos_barometer_mpl3115_detect(struct mgos_barometer *dev) {
-  return false;
+  int val;
+
+  if (!dev) {
+    return false;
+  }
+
+  if ((val = mgos_i2c_read_reg_b(dev->i2c, dev->i2caddr, MPL3115_REG_WHOAMI)) < 0) {
+    return false;
+  }
+
+  if (val != 0xC4) {
+    return false;
+  }
+
+  return true;
 }
 
 bool mgos_barometer_mpl3115_create(struct mgos_barometer *dev) {
-  return false;
-}
+  if (!dev) {
+    return false;
+  }
 
-bool mgos_barometer_mpl3115_destroy(struct mgos_barometer *dev){
-  return false;
+
+  // Reset
+  if (!mgos_i2c_write_reg_b(dev->i2c, dev->i2caddr, MPL3115_REG_CTRL1, 0x04)) {
+    return false;
+  }
+  mgos_usleep(20000);
+
+  // Set sample period to 1sec ST[3:0], period 2^ST seconds
+  if (!mgos_i2c_write_reg_b(dev->i2c, dev->i2caddr, MPL3115_REG_CTRL2, 0x00)) {
+    return false;
+  }
+
+  // Set Barometer Mode, OS[2:0], oversampling 2^OS times, continuous sampling
+  if (!mgos_i2c_write_reg_b(dev->i2c, dev->i2caddr, MPL3115_REG_CTRL1, 0x39)) {
+    return false;
+  }
+
+  // Set event flags for temp+pressure
+  if (!mgos_i2c_write_reg_b(dev->i2c, dev->i2caddr, MPL3115_REG_PT_DATA, 0x07)) {
+    return false;
+  }
+
+  dev->has_barometer   = true;
+  dev->has_thermometer = true;
+
+  return true;
 }
 
 bool mgos_barometer_mpl3115_read(struct mgos_barometer *dev) {
-  return false;
+  if (!dev) {
+    return false;
+  }
+
+  uint8_t val = 0;
+  while (!(val & 0x80)) { // Data Ready
+    if ((val = mgos_i2c_read_reg_b(dev->i2c, dev->i2caddr, MPL3115_REG_STATUS)) < 0) {
+      return false;
+    }
+    mgos_usleep(10000);
+  }
+
+  uint32_t pressure;
+  int16_t  temperature;
+  uint8_t  data[5];
+
+  if (!mgos_i2c_read_reg_n(dev->i2c, dev->i2caddr, MPL3115_REG_PRESSURE_MSB, 5, data)) {
+    return false;
+  }
+
+  pressure   = data[0];
+  pressure <<= 8;
+  pressure  |= data[1];
+  pressure <<= 8;
+  pressure  |= data[2];
+  pressure >>= 4;
+
+  temperature   = data[3];
+  temperature <<= 8;
+  temperature  |= data[4];
+  temperature >>= 4;
+  if (temperature & 0x800) {
+    temperature |= 0xF000;
+  }
+
+  dev->pressure    = pressure / 4.0;
+  dev->temperature = temperature / 16.0;
+  return true;
 }

src/mgos_barometer_mpl3115.h

@@ -3,11 +3,18 @@
 #include "mgos.h"
 #include "mgos_barometer_internal.h"
 
-struct mgos_barometer_mpl3115_data {
-  float a0, b1, b2, c12;
-};
+#define MPL3115_REG_STATUS          (0x00)
+#define MPL3115_REG_PRESSURE_MSB    (0x01)
+#define MPL3115_REG_PRESSURE_CSB    (0x02)
+#define MPL3115_REG_PRESSURE_LSB    (0x03)
+#define MPL3115_REG_TEMP_MSB        (0x04)
+#define MPL3115_REG_TEMP_LSB        (0x05)
+#define MPL3115_REG_DR_STATUS       (0x06)
+#define MPL3115_REG_WHOAMI          (0x0C)
+#define MPL3115_REG_PT_DATA         (0x13)
+#define MPL3115_REG_CTRL1           (0x26)
+#define MPL3115_REG_CTRL2           (0x27)
 
 bool mgos_barometer_mpl3115_detect(struct mgos_barometer *dev);
 bool mgos_barometer_mpl3115_create(struct mgos_barometer *dev);
-bool mgos_barometer_mpl3115_destroy(struct mgos_barometer *dev);
 bool mgos_barometer_mpl3115_read(struct mgos_barometer *dev);