Hope RF HP01-TQ BAROMETER MODULE 2011-4-20 PRELIMINARY Version: 2.2 . Integrated pressure sensor . Pressure Range 750-1100hpa . 16 Bit Σ−Δ ADC . I2C Serial Interface . One system clock line (32768Hz) . Low voltage, low power Description The HP01 pressure module includes a piezo-resistive pressure sensor and an ADC interface. It provides 16 bit word data for pressure and temperature related voltage. HP01 is a low power, low voltage device with automatic power down switching. I2C Serial Interface is used for communications with a microprocessor. Features . 14 Bit ENOB ADC resolution . Supply voltage 2.2-3.6v . -40°C to + 85°C operating range Applications . Pressure measurement and control systems . Weather forecast products Block Diagram 1 Hope RF HP01-TQ BAROMETER MODULE PRELIMINARY 2011-4-20 Version: 2.2 Pin Name VSS VDD MCLK XCLR* SDA Pin Number 1 2 3 4 5 Type G P I I I/O Function power ground power VCC master clock(32k) input ADC reset inpu . I²C data input and output SCL 6 I I2C clock input * XCLR is to reset the AD converter (active low). During the AD conversion phase, XCLR should stay high. After AD conversion end, keep XCLR pin low before another AD conversion starts. Absolute Maximum Ratings Parameter Supply Voltage Over pressure Symbol VDD P Min -0.3 Max 4.0 5 Unit V Bar(abs) Storage Temperature Tstg -40 125 °C Recommended Operating Conditions Parameter Supply Voltage Supply Current Symbol VDD I Conditions Min 2.2 Typ 3 Unit V V VDD=3V During conversion μΑ μΑ 500 Stand by Operating Pressure Range Operating Temperature Range Conversion Time Duty Cycle of MCLK Serial Date Rate Max 3.6 1 P 900 T T -40 25 MCLK=32k 40% 50% SCL 1100 Hpa (abs) 85 35 60% 100 °C ms % KHZ Pressure and Temperature Output Characteristics HP01 system is able to reach the following characteristics: Parameter Resolution Accuracy Symbol Pressure Sensitivity SNS Conditions Maximum Error Over Temperature Long Term Stability VDD Dependency Temperature coefficient of sensitivity TCS 2 Typ 900-1100 Min 0.1 -8 900-1100 25 27 0~+55 12 month 2.0~5.0 -5.0 Max +10 Unit hpa hpa 30 Cnts/mbar 5.0 -1.5 1 0 1.5 hpa hpa hpa -0.45 -0.55 -0.6 ∆D1/∆D2 Hope RF HP01-TQ BAROMETER MODULE PRELIMINARY 2011-4-20 Version: 2.2 Pressure Measurement The main function of HP01 system is to convert the uncompensated pressure and temperature signal from a pressure sensor. After the conversion, the following two values can be obtained: . measured temperature “D2” . measured pressure “D1” As the sensor is strongly temperature dependent, it is necessary to compensate for these effects. Therefore necessary temperature compensation is needed to achieve nominal accuracy. Pressure and Temperature Compensation Calculation: The following information is just a guide line for temperature compensate, the end user of this module should not be confined to this method. Many other methods can be deployed to achieve best accuracy. Step 1: (set relative pressure starting reference point, normally this step be done after power up or reset relative pressure) P0=1013.2hp D1(P0)=D1 D2(P0)=D2 Step 2: (normal pressure calculation with first order temperature compensation) dUT=D2-D2(P0) dTCS=TCS*dUT dUP=D1-dTCS-D1(P0) P2=dUP/SNS P=P0+P2 ; calculate current temperature difference with reference temperature ; calculate compensated pressure offset with temperature coefficients ; calculate temperature compensated pressure reading ; calculate pressure difference referred to starting pressure P0 ; calculate current relative pressure Example: D1(P0)=30000 D2(P0)=4100 TCS=-0.55 SNS=27 (obtained after power up reading: D1) (obtained after power up reading: D2) (nominal module value from this data sheet) (nominal module value from this data sheet) D1=30036 D2=4107 (current pressure AD reading from module) (current temperature AD reading from module) dUT = 4107-4100 = 7 dTCS=-0.55*7=-3.85 dUP=30036+3.85-30000=39 3 Hope RF HP01-TQ BAROMETER MODULE 2011-4-20 PRELIMINARY Version: 2.2 P2=39/27=1.44 P=1013.2+1.44=1014.6 Serial Interface The I2C interface is used for reading measurement result from AD conversion:D1 and D2. Reading Temperature and Pressure value:D1,D2 AD chip I2C address is set to 0xEE (device write address), 0xEF (device read address). In order to get the AD value D1 and D2, you have to follow the following timing sequence: Pressure Measure: S 11101110 A 11111111 A 11110000 A P D S 11101110 A 11111101 A S 11101111 A MSB A LSB N P Select pressure measurement Read AD value back Temperature Measure: S 11101110 A 11111111 A 11101000 A P D S 11101110 A 11111101 A S 11101111 A MSB A LSB N P Select temperature measurement Read AD value back S: I2C bus START (refer to AT24C02 EEPROM start command) P: I2C bus STOP (refer to AT24C02 EEPROM stop command) A (bold): I2C bus acknowledge by slave (SDA pull low: slave send out bit 0) A: I2C bus acknowledge by master (SDA pull low: master send out bit 0) N: I2C bus no acknowledge from master (SDA keep high: master send out bit 1 instead) D : delay for 38ms or above MSB: conversion result (MSB bit clocked out first) LSB: conversion result (MSB bit clocked out first). Remark: Before start an AD conversion cycle, remember to set XCLR pin high so that the system is no longer in the reset state (not valid for HP01). 4 Hope RF HP01-TQ BAROMETER MODULE 2011-4-20 PRELIMINARY Version: 2.2 All data read from the module is in hex format. After first power on, the first read data should be disregarded, and only the second value be used. This can assure that unstable reading after power on reset can be filtered out. Like any other semiconductor device, the sensor is sensitive to light. During the application of this sensor, please keep the sensor in dark place to achieve best accuracy. Since the module is not calibrated for sensitivity and temperature, thus only relative pressure can be calculated. If you need higher accuracy with temperature, please refer to our HP02 or HP03 series pressure module accordingly. Typical Application Circuit Diagram: Remark： In the battery supply product this application need be changed as: 32 KHz signal is outputted via the port of the MCU instead of the 32.768 KHz crystal to MCLK pin. The MCU will not output 32 KHz signal and keep low level when the HP01 enter to standby mode. 5 Hope RF HP01-TQ BAROMETER MODULE 2011-4-20 PRELIMINARY Version: 2.2 HP01-TQ Mechanical Dimension Important Notices Never unplug the module when power is on. Do not use this product as safety or emergency stop device or in any application where failure of this product could lead in personal injury. Failure to comply with these instructions could result with death or serious injury. Should buyer purchase or use HOPE RF products for any such unintended or unauthorized application, buyer should indemnify and hold HOPE RF and its officers, employees, affiliates and distributors harmless against all claims, costs, damages and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury associated with such unintended or unauthorized use, even if such claim alleges that HOPE RF was negligent regarding the design or manufacturing of the part. Hope RF reserves the right, without further notice, to change the product specification and/or information in this document and to improve reliability, functions and design. 6