Isaac Khader
htu21d_for_weather_shield
Dependents: SPARKFUN_WEATHER_SHIELD
Fork of
htu21d
by 
Kevin Braun
Diff: htu21d.h
- Revision:
- 1:d3ed713f8354
- Parent:
- 0:2dab43acb3a4
- Child:
- 3:5c0f8e91d319
--- a/htu21d.h Wed May 14 00:31:30 2014 +0000
+++ b/htu21d.h Thu May 15 19:12:11 2014 +0000
@@ -1,5 +1,8 @@
/**
- */
+HTU21D / HPP828E031 driver for mbed.
+- Includes RTOS hooks if RTOS is detected during compile.
+Author: Kevin Braun
+ **/
#ifndef HTU21D_H
#define HTU21D_H
@@ -16,116 +19,239 @@
#define HTU21DhumNOHOLD 0xF5
#define HTU21DRESET 0xFE
+#define HTU21SNAC1 0xFC
+#define HTU21SNAC2 0xC9
+#define HTU21SNB1 0xFA
+#define HTU21SNB2 0x0F
+
#define HTU21DHEATER 0x04
-/**
- * Honeywell HTU21D digital humidity and temperature sensor.
- */
+ /**
+ * measurement specialties / Honeywell HTU21D digital humidity and temperature sensor.
+ * - Web site: http://www.meas-spec.com
+ * - Part Number: HPP828E031
+ * - HTU21D = +-3% rh error at 55%
+ * - HTU20D = +-5% rh error at 55%
+ * - Main code generated from datasheet dated October 2013
+ * - Serial number code generated from App Note "HTU2X Serial Number Reading", dated Februrary 2014
+ * - No checksum checking is performed in this code
+ *
+ * @code
+ * //Tested on FRDM-K64F
+ *
+ * #include "mbed.h"
+ * #include "htu21d.h"
+ *
+ * #define SDA PTE25
+ * #define SCL PTE24
+ *
+ * Serial pc(USBTX, USBRX); //local terminal
+ * htu21d htu(SDA, SCL); //Temp Hum || sda, scl
+ *
+ * float H21Temp = 0.0; //Temperture from HTU21D
+ * float H21Hum = 0.0; //Humidity from HTU21D
+ * float H21Dew = 0.0; //Dew Point from HTU21D
+ *
+ * //Note: If RTOS is used, Mutex for I2C must be initialized
+ * #ifdef RTOS_H
+ * Mutex MutexI2cWait;
+ * #endif
+ *
+ * int main() {
+ * pc.baud(230400); //local terminal baud
+ * pc.printf("\r\n\r\nK64F_HTU21D basic operation\r\n");
+ *
+ * //initialize the HTU21D
+ * int htu21 = htu.softReset();
+ * if(htu21 == 0) {
+ * pc.printf(" - HTU21D broken...\r\n");
+ * } else {
+ * uint8_t HTU21DuserReg = htu.getUserReg();
+ * pc.printf("HTU21D UserReg: 0x%02x SN: 0x%04x %08x %04x\r\n",
+ * HTU21DuserReg, htu.HTU21sn.HTU21D_sna, htu.HTU21sn.HTU21D_snb, htu.HTU21sn.HTU21D_snc);
+ * }
+ *
+ * while(true) {
+ * //get humidity, temperature and dew point from HTU21D
+ * if(htu21 == 1) { //if HTU21D didn't initialize, don't access HTU21D anymore
+ * H21Hum = htu.getHum();
+ * if((double)H21Hum == 255.0) pc.printf("\r\n*** HTU21D Hum error!!\r\n");
+ * H21Temp = htu.getTemp();
+ * if((double)H21Temp == 255.0) pc.printf("\r\n*** HTU21D Temp error!!\r\n");
+ * H21Dew = htu.getDewPtFast();
+ * }
+ * pc.printf("Temp: %7.2f C %7.2f F Hum: %4.1f %% DewPt: %7.2f C\r\n", H21Temp, H21Hum, H21Dew);
+ * wait(1.0);
+ * }
+ * }
+ * @endcode
+ **/
class htu21d {
public:
/**
- * Constructor.
+ * Constructor
+ * - Fixed at I2C address 0x80
+ * - I2C speed set to 400000
*
- * @param sda and scl, mbed I2C interface pins.
+ * @param PinName sda and scl, mbed I2C interface pins
*/
htu21d(PinName sda, PinName scl);
/**
- * De-constructor.
+ * Constructor
+ * - Fixed at I2C address 0x80
+ * - I2C speed set by user
*
- * @param --none--.
+ * @param PinName sda and scl, mbed I2C interface pins
+ * @param int I2C frequency
+ */
+ htu21d(PinName sda, PinName scl, int i2cFrequency);
+ /**
+ * Destructor
+ *
+ * @param --none--
*/
~htu21d();
/**
- * Get HTU21D Temperature.
+ * Reset the HTU21D chip
+ * - Waits 15mS before exiting, allowing the chip reset to finish
+ * - Executes getSNReg() which loads up HTU21D serial number structure
*
- * @param --none--.
+ * @param --none-- NOTE: run softReset() once at initialization time
*
- * @return success / failure of HTU21D i2c access. 1 = ok, 0 = error.
+ * @return success / failure of HTU21D i2c access. 1 = ok, 0 = error
*/
int softReset();
/**
- * Get HTU21D user register.
+ * Get HTU21D user register
*
- * @param --none--.
+ * @param --none--
*
- * @return success / failure of HTU21D i2c access. 1 = ok, 0 = error.
+ * @return 8 bit user register value
*/
uint8_t getUserReg();
/**
- * Turn ON the heater in the HTU21D.
+ * Turn ON the heater on the HTU21D
*
- * @param --none--.
+ * @param --none--
*
- * @return success / failure of HTU21D i2c access. 1 = ok, 0 = error.
+ * @return success / failure of HTU21D i2c access. 1 = ok, 0 = error
*/
int heaterOn();
/**
- * Turn OFF the heater in the HTU21D.
+ * Turn OFF the heater on the HTU21D
*
- * @param --none--.
+ * @param --none--
*
- * @return --none--.
+ * @return success / failure of HTU21D i2c access. 1 = ok, 0 = error
*/
int heaterOff();
/**
- * Get heater on/off status in the HTU21D.
+ * Get heater on/off status of the HTU21D
*
- * @param --none--.
+ * @param --none--
*
- * @return 4 = on, 0 = 0ff.
+ * @return 0x04 = on, 0 = off
*/
uint8_t getHeater();
/**
- * Do a reset on the HTU21D.
+ * Get HTU21D Temperature
*
- * @param --none--.
+ * @param --none--
*
- * @return float of Temperature in degrees C. 255.0 if error.
+ * @return float of Temperature in degrees C. 255.0 if error
*/
float getTemp();
/**
- * Get HTU21D Humidity.
+ * Get HTU21D Humidity
*
- * @param --none--.
+ * @param --none--
*
- * @return float of Humidity in percentage. 255.0 if error.
+ * @return float of Humidity in percentage. 255.0 if error
*/
float getHum();
/**
- * Claculate the Dew Point.
+ * Calculate the Dew Point
*
- * @param MUST run getTemp and getHum first!!
+ * @param --none-- NOTE: You MUST run getTemp() and getHum() first!!
*
- * @return float of Dew Point.
+ * @return float of Dew Point
*/
float getDewPt();
/**
- * Claculate the Dew Point. 5x faster than getDewPt().
+ * Calculate the Dew Point fast
+ * - 5x faster than getDewPt()
+ * - slightly less accurate than getDewPt()
*
- * @param MUST run getTemp and getHum first!!
+ * @param --none-- NOTE: You MUST run getTemp() and getHum() first!!
*
- * @return float of Dew Point.
+ * @return float of Dew Point
*/
float getDewPtFast();
-
-
+ /**
+ * Structure to access HTU21D's serial number
+ * - HTU21D_sna is the hi 16 bit word of the s/n, always is 0x4854
+ * - HTU21D_snb is the mid 32 bit word of the s/n, 0x00--------
+ * - HTU21D_snc is the low 16 bit word of the s/n, 0x32--
+ * - The complete 64 bit s/n value is: 0x48 54 00 -- -- -- 32 --
+ * - The numbers shown are fixed fields
+ * - The '-' numbers are variable
+ * - For reference, the CRC values for the s/n are included
+ */
+ struct HTU21snStruct {
+ uint16_t HTU21D_sna; /**< Highest order 16 bit word of SN
+ - Value always = 0x4854
+ */
+ uint32_t HTU21D_snb; /**< Middle order 32 bit word of SN
+ - Value = 0x00--------
+ - Highest byte always = 0x00
+ - Lower 3 bytes are variable
+ */
+ uint16_t HTU21D_snc; /**< Lowest order 16 bit word of SN
+ - Value = 0x32--
+ - Highest byte always = 0x32
+ - Lowest byte is variable
+ */
+ uint8_t HTU21D_crca; /**< Single byte checksum from HTU21D_sna
+ */
+ uint32_t HTU21D_crcb; /**< Four byte checksum from HTU21D_snb
+ */
+ uint8_t HTU21D_crcc; /**< Single byte checksum from HTU21D_snc
+ */
+ HTU21snStruct() {
+ HTU21D_sna = 0;
+ HTU21D_snb = 0;
+ HTU21D_snc = 0;
+ HTU21D_crca = 0;
+ HTU21D_crcb = 0;
+ HTU21D_crcc = 0;
+ }
+ } HTU21sn;
private:
I2C _i2c;
/**
- * I2C access for getting raw Temperature and Humidity data.
+ * I2C access for getting raw Temperature and Humidity data
*
- * @param 8 bit HTU21D register to get data from. Must use non-blocking regs.
+ * @param 8 bit HTU21D register to get data from. Must use non-blocking regs
*
- * @return 16 bit raw i2c data, ANDed to 14 bits 0xFFFC. 0000 if error.
+ * @return 16 bit raw i2c data, ANDed to 14 bits 0xFFFC. 0000 if error
*/
uint16_t getData(uint8_t reg);
+ /**
+ * Get the HTU21D's serial number.
+ * - Number returned is 0x4854 00-- ---- 32--
+ * - The numbers shown are fixed fields
+ * - The '-' numbers are variable
+ *
+ * @param --none--
+ *
+ * @return --none--
+ */
+ void getSNReg();
double theTempIs;
double theHumIs;
- float getTrash();
-
};
#endif