Add mgos_barometer API

src/mgos_barometer_mpl115.c

@@ -0,0 +1,62 @@
+#include "mgos_barometer_mpl115.h"
+#include "mgos_i2c.h"
+
+bool mgos_barometer_mpl115_create(struct mgos_barometer *dev) {
+  struct mgos_barometer_mpl115_data *mpl115_data;
+
+  if (!dev) return false;
+  uint8_t data[8];
+  if (!mgos_i2c_read_reg_n(dev->i2c, dev->i2caddr, MPL115_REG_COEFF_BASE, 8, data))
+    return false;
+
+  mpl115_data=calloc(1, sizeof(struct mgos_barometer_mpl115_data));
+  if (!mpl115_data) return false;
+
+  mpl115_data->a0=(float)(((uint16_t) data[0] << 8) | data[1]) / 8.0;
+  mpl115_data->b1=(float)(((uint16_t) data[2] << 8) | data[3]) / 8192.0;
+  mpl115_data->b2=(float)(((uint16_t) data[4] << 8) | data[5]) / 16384.0;
+  mpl115_data->c12=(float)((((uint16_t) (data[6] << 8) | data[7])) >> 2) / 4194304.0;
+  dev->user_data=mpl115_data;
+  LOG(LL_DEBUG, ("Calibration data: a0=%.4f b1=%.4f b2=%.4f c12=%.4f", mpl115_data->a0, mpl115_data->b1, mpl115_data->b2, mpl115_data->c12));
+
+  dev->has_barometer=true;
+  dev->has_thermometer=true;
+  return true;
+}
+
+bool mgos_barometer_mpl115_destroy(struct mgos_barometer *dev) {
+  if (!dev) return false;
+  if (dev->user_data) {
+    free(dev->user_data);
+    dev->user_data=NULL;
+  }
+  return true;
+}
+
+bool mgos_barometer_mpl115_read(struct mgos_barometer *dev) {
+  struct mgos_barometer_mpl115_data *mpl115_data;
+  uint16_t Padc, Tadc;
+  float Pcomp;
+
+  if (!dev) return false;
+  mpl115_data=(struct mgos_barometer_mpl115_data *) dev->user_data;
+  if (!mpl115_data) return false;
+
+  if (!mgos_i2c_write_reg_b(dev->i2c, dev->i2caddr, MPL115_REG_START, 0x00))
+    return false;
+
+  mgos_usleep(4000);
+  uint8_t data[4];
+  if (!mgos_i2c_read_reg_n(dev->i2c, dev->i2caddr, MPL115_REG_PRESSURE, 4, data))
+    return false;
+  Padc=(((uint16_t) data[0] << 8) | data[1]) >> 6;
+  Tadc=(((uint16_t) data[2] << 8) | data[3]) >> 6;
+
+  Pcomp= mpl115_data->a0 + (mpl115_data->b1 + mpl115_data->c12 * Tadc ) * Padc + mpl115_data->b2 * Tadc;
+
+  dev->pressure= 1000*Pcomp*(65.0/1023) + 50.0;        // Pascals
+  dev->temperature=((float) Tadc - 498.0F) / -5.35F +25.0F;           // Celsius
+
+  return true;
+}
+