High resolution barometer and altimeter using i2c mode
Dependents: upverter_fitbit_clone ReadingMag_HMC5883L_work
Diff: ms5611.h
- Revision:
- 0:f97f410d4a21
- Child:
- 1:94a46b4fed9d
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/ms5611.h Tue May 07 18:44:06 2013 +0000 @@ -0,0 +1,127 @@ +#ifndef MS5611_H +#define MS5611_H + +#include "mbed.h" + +/** Software routines to access the Measurement Specialties' MS5611-01BA03 + * Variometer Module using the I2C bus option. The MS5611 is a 24 bit + * temperature and pressure transducer for high accuracy Barometer and + * Altimeter applications. It also includes compensation coefficients + * stored within the device. + * + * Code adapted from Measurement Specialties: + * "AN520 C-code example for MS56xx, MS57xx (except analog sensor), and + * MS58xx series pressure sensors" + * + * Note: AN520 has not been updated for use with the MS5611. Changes + * were necessary to "calcPT()" in order to correct scaling of + * pressure readings. + * + * Features: + * Altitude resolution to 10cm + * Fast conversion down to 1 ms + * Low power, 1 μA (standby < 0.15 μA) + * QFN package 5.0 x 3.0 x 1.0 mm^3 + * Supply voltage 1.8 to 3.6 V + * Integrated digital pressure sensor (24 bit DeltaSigma ADC) + * Operating range: 10 to 1200 mbar, -40 to +85 °C + * I2C and SPI interface up to 20 MHz + * No external components (Internal oscillator) + * Excellent long term stability + * + * @code + * #include "mbed.h" + * #include "ms5611.h" + * + * ms5611 ms(p9, p10); // i2c pins used + * Serial pc(USBTX, USBRX); // local terminal interface + * + * + * int main (void) { + * pc.baud(921600); // set up USB serial speed + * i2c.frequency(400000); // set up i2c speed + * + * // set up the ms5611 + * pc.printf("\n\nInitializing the MS5611..\n"); + * ms.cmd_reset(); + * pc.printf("Ready\n"); + * + * while(1) { + * double Temp = ms.calcTemp(); + * double Press = ms.calcPressure(); + * pc.printf("Temp: %.2f degC Barometer: %.1f mB %.3f in/Hg\n", Temp, Press, Press * 0.0295301); + * wait(2.0); + * } + * } + * + * @endcode + */ + +//_____ M A C R O S + +#define MS5611_ADDR_W 0xEE // Module address write mode +#define MS5611_ADDR_R 0xEF // Module address read mode +#define MS5611_CMD_RESET 0x1E // ADC reset command +#define MS5611_CMD_ADC_READ 0x00 // ADC read command +#define MS5611_CMD_ADC_CONV 0x40 // ADC conversion command +#define MS5611_CMD_ADC_D1 0x00 // ADC D1 conversion +#define MS5611_CMD_ADC_D2 0x10 // ADC D2 conversion +#define MS5611_CMD_ADC_256 0x00 // ADC OSR=256 +#define MS5611_CMD_ADC_512 0x02 // ADC OSR=512 +#define MS5611_CMD_ADC_1024 0x04 // ADC OSR=1024 +#define MS5611_CMD_ADC_2048 0x06 // ADC OSR=2048 +#define MS5611_CMD_ADC_4096 0x08 // ADC OSR=4096 +#define MS5611_CMD_PROM_RD 0xA0 // Prom read command + +/* MS5611 controller class + */ +class ms5611{ + +public: + /** Create a MS5611 object using the specified I2C object + * + * @param constructor, - the I2C object to communicate with + */ + ms5611(PinName sda, PinName scl); + /** Initialize the MS5611 and set up the coefficients + * First - reset the MS5611 + * Second - load coefficient values from the MS5611 PROM + * Third - calculate coefficient checksum + * This routine only needs to be run once at boot up + * + * @param NONE + */ + void cmd_reset(); + /** Calculate and return compensated temperature + * Returns double temperature in degC + * + * @param NONE + */ + double calcTemp(); + /** Calculate and return compensated barometric pressure + * Returns double pressure in millibars + * + * @param NONE + */ + double calcPressure(); + +private: + int m_i2c_start(bool readMode); + void m_i2c_stop(void); + unsigned char m_i2c_write(unsigned char data); + unsigned char m_i2c_readAck(void); + unsigned char m_i2c_readNak(void); + void m_i2c_send(char cmd); + void loadCoefs(); + unsigned long cmd_adc(char cmd); + unsigned int cmd_prom(char coef_num); + unsigned char crc4(unsigned int n_prom[]); + void calcPT(); + unsigned int PTbuffer[8]; // calibration coefficients + +protected: + I2C _i2c; + + +}; +#endif