Manual iAQ-engine - Mikrocontroller.net
Contents
1. Sensing range lC 450 65535 ppm COs equivalents relative DAC 450 2000 ppm CO equivalents relative Automatic baseline correction Manual iAQ engine all data subject to change without notice Applied Sensor 4 I C Interface 4 1 Interface description 4 1 1 Physical interface The physical interface is two wire open drain SCL clock and SDA data Pull up resistors External pull up resistor required Clock speed 100kKHz Clock stretching Bus master clock stretching support is required 4 1 2 Clock stretching Clock stretching pauses a transaction by holding the clock line low The transaction cannot continue until the line is released to high again Although the module could send the bytes of data at a fast rate it could happen that the module is busy at the request time It can then hold the clock line low after reception and acknowledgement of a byte to force the master into a wait state until the iAQ engine module is ready for the next byte transfer in a type of handshake procedure See official I C specification and user manual UM10204 http www nxp com documents user_manual UM10204 pdf 4 1 3 Address Standard 7 bit I C address for iAQ engine is decimal 90 or hexadecimal 0x5A The addressing byte includes the read write bit at the lowest significant bit The communication with the iAQ engine starts with 0xB5 for reading data Address Address RW Bit_ 7 6 5 4 3 2 1 0 daaj1jo ij1joji o 12. The master answeres with an Acknowledge AppliedSensor Manual iAQ engine all data subject to change without notice MSb Byte 3 resistance LSb MSb LSb Figure 5 The last four bytes contain the resistance value For the calculation of the resistance only byte4 byte5 and byte 6 are relevant because byte3 is zero After the last requested byte the master sends a not Acknowledge 4 2 1 Prediction The first two bytes contain the prediction value which gives the information about the indoor air quality The value is a CO equivalent and the calculation is shown in the following example Equation 1 Manual iAQ engine all data subject to change without notice Applied Sensor 4 2 2 Status Flag The third byte indicates status of the module e 0x00 OK e 0x01 BUSY e 0x80 ERROR lf status is OK the data is valid If the status is BUSY the data integrity is not guaranteed for variables of size gt 8 bits because the module may be updating a part of the variable If the status is ERROR constantly or very frequently this indicates that the module is reading non realistic values and the sensor element is probably defective 4 2 3 Resistance The next four bytes contain the sensor resistance in Ohm The fourth byte of the int32 variable is 0 Equation 2 4 3 Typical applications VCC 4k7 4k7 Microcontroller SCL ae GND SDA Figure 6 Simple microcontroller application Manual iAQ engine all
3. Manual iAQ engine Version 2 0 May 2011 all data subject to change without notice Applied Sensor Manual iAQ engine Indoor Air Quality sensor e Digital and analog I O e SMD type package Product summary iAQ engine is used for measuring VOC levels that can The sensor itself is protected by a plastic cap and a be read out as a prediction via the I C bus The iAQ filter membrane The sensor module can be soldered engine can also control equipment directly by an directly to a host circuit board with selective soldering analog output with a 0 5 V DAC Dimensions 7 6 Pin Name Comment a Te vee fv PCB 15 24 x 17 78 mm HEIGHT PCB 1 7 mm Dimensions approximate values HOOD 11 2 x 17 78 mm TOTAL HEIGHT 4 3 mm Sensor position approximate 7 6 x 12 3 mm values Radius 3 5 mm Figure 1 iAQ engine sensor dimensions in mm Top View Weight Approximately 1g Connector Card edge cut via Manual iAQ engine all data subject to change without notice Applied Sensor 1 Electrical specifications 1 1 Power supply Voltage 5 0 0 25V max 20mV ripple Note Module features a decoupling capacitor 1 2 Communication Output signal options For more communication details see chapter 4 2 Environmental Temperature range operation 0 to 50 Temperature range storage 25 to 50 Humidity range 5 to 95 r h non condensing 3 Sensor Features Sensing technology MEMS metal oxide sensor
4. Table 1 Addressing byte for the iAQ engine 4 2 Interface protocol The standard C specification is used for the iAQ engine interface protocol The I C bus master should request 7 bytes These seven bytes include information about the indoor air quality value the iAQ engine status and the resistance of the sensor If there is a need just for the indoor air quality value and the status the master should request three bytes from the iAQ engine All bytes are reported back as shown in the following table A graphical description for a standard 1 C communication with the iAQ engine module is shown in figure 2 figure 5 Byte Name Datatype Typical example value Explanation notes 0 1 pred sit 6 4500 Prediction ppm 0x00 OK data valid status uint8 0x01 BUSY re read multi byte data 0x80 ERROR if constant replace sensor 3 6 resistance int32 256431 Sensor resistance Ohm Table 3 Read data from the iAQ engine Manual iAQ engine all data subject to change without notice Applied Sensor Figure 2 The first byte is send by the master containing address Ox5A and read write bit The slave sends an acknowledgement ACK by pulling the data line to low Figure 3 The slave will answer by sending bytes with MSB first ByteO and byte1 contain the prediction value All bytes are Acknowledged by the master Figure 4 The third byte contains the information of the iAQ engine module state in this case status 1
5. data subject to change without notice Applied Sensor 4 4 Recommended footprint 15 2 2 54 Figure 7 Recommended footprint standard 4 5 Ordering information 60 0100 AppliedSensor is not responsible for the design implementation manufacture or results from use of products that incorporate AppliedSensor components unless expressly agreed to in writing Prior to using or distributing any product that incorporates ApplledSensor components users and distributors should assure adequate design testing and operating safeguards and consult with AppledSensor s technical staff as necessary All AppliedSensor components and services are soki subject to AppliedSensor s terms and conditions of sale For the most current AppiledSensor product information and terms and conditions of sale visit us at waw_appliedsensor com ApplledSensor and the AppliedSensor logo are trademarks of AppliadSensor Sweden AB AppliedSensor GmbH and AppliedSensor Inc Copyright 2010 AppliedSensor Sweden AB 02 11 AppliedSensor Sweden AB AppliedSensor GmbH AppliedSensor Inc Dakotigatan 11 Gamard Kinder St 8 63 Mountain Boulevard Applied Sensor SE 583 35 Link ping Sweden 72770 Reutlingen Germany Warren NJ 07059 USA Tel 46 13 262 900 Tel 49 7121 51486 0 Tel 1 908 222 1477 Fax 46 13 262 929 Fax 49 7121 51486 29 Fax 1 908 222 1478 www appliedsensor com
Download Pdf Manuals
Related Search