Diff: hts221.cpp

Revision:

0:030da9425166

Child:

1:da79e74eadd1

diff -r 000000000000 -r 030da9425166 hts221.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hts221.cpp	Fri Jan 30 08:49:01 2015 +0000
@@ -0,0 +1,163 @@
+/* Copyright (c) 2009 Nordic Semiconductor. All Rights Reserved.
+ *
+ * The information contained herein is property of Nordic Semiconductor ASA.
+ * Terms and conditions of usage are described in detail in NORDIC
+ * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
+ *
+ * Licensees are granted free, non-transferable use of the information. NO
+ * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
+ * the file.
+ *df
+ */
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include <mbed.h>
+#include "hts221.h"
+
+I2C i2c(p22, p20);    //SDA, SCL
+
+
+/*lint ++flb "Enter library region" */
+
+// Gill
+
+
+//
+
+static const char expected_who_am_i = 0xBCU; //!< Expected value to get from WHO_AM_I register.
+
+uint8_t H0_rH_x2; 
+uint8_t H1_rH_x2;
+uint16_t T0_degC_x8;
+uint16_t T1_degC_x8;
+
+int16_t H0_T0_OUT;
+int16_t H1_T0_OUT;
+int16_t T0_OUT;
+int16_t T1_OUT;
+
+float T0_DegC_cal;
+float T1_DegC_cal;
+float H0_RH_cal;
+float H1_RH_cal;
+
+bool hts221_init(void)
+{   
+  bool transfer_succeeded = true;
+
+  i2c.frequency(400000);
+    hts221_register_write(0x10 , TRes_4 << 3 | HRes_5); 
+    hts221_register_write(0x20 , PD_On | BDU_On  | ODR_1Hz); // Control register 1
+    hts221_register_write(0x21 , NoBoot | HeaterOff  | No_OS); // Control register 2
+    hts221_register_write(0x22 , DRDY_H | PP_OD_PP | DRDY_NON); // Control register 3
+                                
+  // Read and verify product ID
+  transfer_succeeded &= hts221_verify_product_id();
+
+  return transfer_succeeded;
+}
+
+bool hts221_verify_product_id(void)
+{
+    char who_am_i[1];
+    hts221_register_read(ADDRESS_WHO_AM_I, &who_am_i[0], 1);
+    if (who_am_i[0] != expected_who_am_i) return false;
+    else return true;
+}
+
+void hts221_register_write(uint8_t register_address, uint8_t value)
+{   
+    char w2_data[2];
+    
+    w2_data[0] = register_address;
+    w2_data[1] = value;
+    i2c.write(HTS221_WriteADDE, w2_data, 2);      
+
+}
+
+void hts221_register_read(char register_address, char *destination, uint8_t number_of_bytes)
+{
+  i2c.write(HTS221_WriteADDE, &register_address, 1, 1);
+  i2c.read(HTS221_WriteADDE, destination, number_of_bytes);   //Note by Tsungta, API may have a bug
+  
+  //runaboud read function added by Tsungta
+/*  if (number_of_bytes == 1) {
+      i2c.write(HTS221_WriteADDE, &register_address, 1, 1);
+      i2c.write(HTS221_ReadADDE);
+      *destination = i2c.read(0);
+      i2c.stop();
+  } else {
+      register_address |= 0x80;
+      i2c.write(HTS221_WriteADDE, &register_address, 1, 1);
+      i2c.write(HTS221_ReadADDE);
+      while (number_of_bytes-- > 0)
+        *destination++ = i2c.read(0);
+      i2c.stop();      
+  }*/    
+}
+               
+void HTS221_Calib(void) 
+{
+    char cal_data[16];
+    
+    hts221_register_read(0xB0, cal_data, 16);
+
+  H0_rH_x2 = cal_data[0]; 
+  H1_rH_x2 = cal_data[1];
+  T0_degC_x8 = ((cal_data[5] & 0x03) << 8) + cal_data[2]; //MSB + LSB in 
+  T1_degC_x8 = ((cal_data[5] & 0x0C) << 6) + cal_data[3]; // MSB
+
+  H0_T0_OUT = (cal_data[7] << 8) + cal_data[6];  
+  H1_T0_OUT = (cal_data[11] << 8) + cal_data[10];
+  T0_OUT = (cal_data[13] << 8) + cal_data[12];
+  T1_OUT = (cal_data[15] << 8) + cal_data[14];
+    
+    // convert negative 2's complement values to native negative value
+    if (H0_T0_OUT&0x8000) H0_T0_OUT = -(0x8000-(0x7fff&H0_T0_OUT));
+    if (H1_T0_OUT&0x8000) H1_T0_OUT = -(0x8000-(0x7fff&H1_T0_OUT));       //((~H1_T0_OUT)+1);//
+    if (T0_OUT&0x8000) T0_OUT = -(0x8000-(0x7fff&T0_OUT));
+    if (T1_OUT&0x8000) T1_OUT = -(0x8000-(0x7fff&T1_OUT));
+    
+  T0_DegC_cal = (float) T0_degC_x8/8;
+  T1_DegC_cal = (float) T1_degC_x8/8;
+  H0_RH_cal = (float) H0_rH_x2/2;
+  H1_RH_cal = (float) H1_rH_x2/2;
+
+}
+    
+void HTS221_ReadTempHumi( float *pTemp , float *pHumi)
+{
+  char sensor_data[4];
+  int16_t H_OUT;
+  int16_t T_OUT;   
+
+    hts221_register_read(0xA8, sensor_data, 4);
+    
+    H_OUT = (sensor_data[1] << 8) + sensor_data[0];
+    T_OUT = (sensor_data[3] << 8) + sensor_data[2];
+    
+    // convert negative 2's complement values to native negative value  
+    if (H_OUT&0x8000) H_OUT = -(0x8000-(0x7fff&H_OUT));   //((~H_OUT)+1);;
+    if (T_OUT&0x8000) T_OUT = -(0x8000-(0x7fff&T_OUT));
+    
+    *pTemp = linear_interpolation(T0_OUT, T0_DegC_cal, T1_OUT, T1_DegC_cal, T_OUT);
+    *pHumi = linear_interpolation(H0_T0_OUT, H0_RH_cal, H1_T0_OUT, H1_RH_cal, H_OUT);
+    // Constraint  for measurement after calibration 
+    if ((int)*pHumi>MaxHumi-1 | (int)*pHumi==-72) *pHumi = MaxHumi;  
+    if ((int)*pHumi<MinHumi ) *pHumi = MinHumi;
+    if ((int)*pTemp>MaxTemp-1) *pHumi = MaxTemp; 
+    if ((int)*pHumi<MinTemp ) *pHumi = MinTemp ;  
+}
+
+float linear_interpolation(int16_t x0, float y0, int16_t x1, float y1, float mes)
+{
+   float a = (float) ((y1 - y0) / (x1 - x0));
+   float b = (float) -a*x0 + y0;
+   float cal = (float) a * mes + b;
+   return cal;
+}
+
+/*lint --flb "Leave library region" */
+