ASAIR AHS01IB User manual

Absolute Humidity Sensor
product manual
AHS01IB
For more detail please check：www.aosong.com

Features
 Working power voltage:+5V
 Operating temperature: -5 to +200℃
（Humidit detection part）
 full calibrated
 I2C digital interface communication
 Power consumption:120mW(maximum)
 Zero-free drift
 Ver long operation life
 High resistance to pollution
 Low humidit lag error
Description
AHS01IB is an absolute humidit sensor
with ultra-high response speed, high
temperature resistance, high accurac and
full calibration. Modern manufacturing
process ensures high reliabilit and
excellent long-term stabilit . The sensor
includes a humidit detection sensor
connected to a CMOS microprocessor with
a high performance integrated 24bitAD.The
product has the advantages of excellent
qualit , ultra-high response speed, strong
anti-interference abilit and ver high cost
effective. With high integration performance,
it is perfectl meet the requirements for
high-qualit mass production.
AHS01IB has I2C digital interface with ver
small size and ver low power consumption.
The working voltage for AHS01IB is 5 Volt
suppl voltage, it could be used to all kinds
of common application scenario provides
low cost and ver low power consumption
advantages. AHS01IB has been calibrated
in high accurac constant temperature and
humidit chamber from our factor , the
output is the real value of environmental
humidit , users can get the accurate
humidit value directl without an signal
processing, which help customers to save
the costs and make the further job much
easier.
Applications
Microwave Humidit Control, Dr er Humidit
Detection, Oven Smart Control, Industrial
Measurement, Air Conditioning and Moisture
Control, Ph sical and Chemical Instruments,
Steam Bath, etc.

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1.Sensor Accuracy
1.1 Accuracy parameters
Table1: AHS01IB performance table
Parameter Condition TYP Units
Operating Range 1atm 0～∞ actual value
T pical output +60℃,30%～
+60℃,60% 900~1300 actual value
Accurac 1atm ±200 actual value
Repeatabilit 1atm ±5% actual value
Stabilization time Power on 8±5 second
Humidit
response 90% response 12±5 second
1.3 Temperature and umidity conditions
Table3: AHS01IB Temperature and umidity conditions
Parameter Condition TYP Units
Operating
Temperature Range
Tsensor -5～+200 ℃
CPU Temperature
Range Twork -20～+85 ℃
Storage Temperature Tstor -20～+85 ℃
Storage humidit Hstor 20%～60% RH
1.2 Sensor material c aracteristics
Table2: Sensibility and materials
Parameter Condition TYP
Sensibilit to gas
（at 1000ppm）
Carbon dioxide -60
Eth l alcohol -60
Isobutane -60
RoHS —— RoHS compliant
Wire for sensor —— high temperature resistant shielded wire

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2. Sensor Electrical C aracteristics
Electrical characteristics depend on the power suppl . Table 4 shows the electrical
characteristics of AHS01IB. If not indicated, the power suppl voltage is 5v.
Table4: AHS01IB Electrical c aracteristics
Parameter Condition MIN TYP MAX Units
Communication I2C
Suppl Voltage VDD 4.75 5 5.25 V
I2C Level High 4 - VDD V
Low GND - 0.8 V
Sampling period 0.5 1 second
Power consumption normal 23 30 mA
standb 1 mA
I2C speed 100 400 Kb/s
3.Sensor parameters limit value
Table5: Parameters Limit Value
Parameter Conditi
on MIN TYP MAX Units
Suppl Voltage VDD -0.3 5.5 V
Storage Temperature
Range TSTOR -20 85 ℃
Note: AHT20 works be ond the above parameters, can cause a certain degree of
irreversible damage to itself.
4. Sensor communication
4.1 Overview of I2C bus
AHS01IB sensor adopts standard I2C communication protocol, which is applicable to a
variet of devices. Two data cables are used in the protocol: serial data bus (SDA) and
serial time bus (SCL), and two data cables need to be connected to the VDD.Multiple

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sensor devices can share the bus;But onl one host device can appear on the bus, the
sensor I2C address is 0x15, the I2C read instruction is 0x2B, and the I2C write instruction
is 0x2A.
If the SCL and DATA signal lines are parallel and ver close to each other, signal crosstalk
and communication ma fail. The solution is to place VDD or GND power signals between
the two signal lines, separate the signal lines for processing or use the shield cable.In
addition, the integrit of signal transmission ma be improved b reducing the frequenc
of SCL.The sensor needs to be wired out, so a 100nF de-coupling capacitance should be
added between the pins of the positive and negative power suppl for filtering.The
capacitance should be as close to the sensor as possible.
4.2 I2C communication interface features and timing
AHS01IB sensor is used as a slave device to support the communication rate up to
400kHz bit rate.When the host sends the start signal (low level), the sensor starts
communication. When the host sends the stop signal (high level), when the secondar
communication ends, the start and end signals are onl valid when the SCL is high power.
Table 6 features and timing
Parameter Condition MIN TYP MAX Units
I2C clock frequenc f SCL 10 400 KHz
Start time t HDSTA 0.8 μs
SCL clock high level width t HIGH 0.6 μs
SCL clock low level width t LOW 0.6 μs
Set time relative to SCL edge start
condition t
SUSTA 0.1 μs
Data save time relative to the SCL
SDA edge t
HDDAT 0 0.5 μs
The data setting time is relative to
the SCL SDA edge t
SUDAT 1 μs
Stop condition setting time in SCL t SUSTO 0.1 μs
Bus free time between stop and
start conditions t
BUS 1 μs

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4.3 I2C communication
When the host initiates the start signal, and the operation mode of the SCL bus satisfies
the above time parameter conditions, the sensor will start communication, and the
command or data will alwa s be sent when the SCL is rising, until the sensor receives the
stop signal sent b the host and ends the communication.
After the initial signal is sent, the host sends an 8-bit read/write instruction, which contains
a high 7-bit address, plus the 8-bit read (1)/ write (0), which will directl determine the
direction of data transmission.When the read instruction 0X2B is sent, it means that the
host reads the slave data and when the write instruction 0X2A is sent, it means that the
host writes the sensor data.
The communication unit for reading and writing data of subsequent sensors includes 8 bit
data bits, and 1 bit response bits; when the response bit is 0(low level), it is ACK(data
response) for communication; and when the response bit is 1(high level), it is NACK(data
no response).When an ACK signal is received from the machine to the host, the next data
unit will be sent, or when the host sends a stop signal, the communication will be
terminated.
4.4 Start of measurement instruction
AHS01IB has been in the state of waiting for the host to send the start command for
measurement and collection.The CPU inside the sensor can now parse the rest of the
instructions, but the rest can't start the data collection.
After the host sends the start command for collection, it can wake up AHS01IB for
self-inspection and collect data periodicall . The start instruction for measurement is
defined as follows:
Table 7 Start of measurement instruction
Command Conditions Hexadecimal code
Start of measurement
instruction
Command MSB 0x06
Command LSB 0x01
4.5 Sensor status register
The status register contains the sensor status bit (bit15:14) and the reserved data bit
(bit13:0), as defined below.

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Table 8 description of sensor status register
Command Conditions
Hexadecimal
code Bit Field description
Quer
sensor
status
Command
MSB 0x0F Bit15:14
00: Sensor to be tested
01: Sensor passed the test
10: Sensor problem
Command
LSB 0x02 Bit13:0 Reserved
When receiving the start instruction of measurement, the module will empt the status
register of the Sensor, automaticall open part of the Sensor power suppl , and start the
self-check of the Sensor. After the self-check, the self-check result of the Sensor will be
written into the status register of the Sensor.
After completion of self-inspection, if the sensor is normal, the module will conduct zero
alignment automaticall and start periodic sensor data collection automaticall .
4.6 Humidity data collection
After self-inspection of the absolute humidit sensor module, the data will be collected at a
period of 500ms. At the end of the measurement c cle, the data output register will be
refreshed.Humidit collection instruction is defined as follows
Table 9 instructions of data collection
Command Conditions
Hexadecimal
code Bit Field description
Humidit
acquisition
Command
MSB 0x00 Bit15:8 Humidit MSB
Command
LSB 0x02 Bit7:0 Humidit LSB

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4.7 End of measurement instruction
When the user does not need the module to work, the sensor power can be cut off b the
end of measurement instruction, and the CPU will stop the collection of humidit and enter
the low-power waiting mode.Humidit collection instruction is defined as follows
Table 10 instructions for end of measurement
Command Conditions Hexadecimal code
End of measurement
instruction
Command MSB 0x07
Command LSB 0x01
4.8 Read device type
Table 11 instructions for device model reading
Command Conditions Hexadecimal code
Read device t pe Command MSB 0x08
Command LSB 0x02

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4.9 Read t e module version
Table 12 version number reads t e description
Command Conditions Hexadecimal code
Read the module version
Command MSB 0x0A
Command LSB 0x01
4.10 Read device ID
Table 13. Description of t e query instruction wit ID number
Command Conditions
Hexadecimal
code Bit Field description
Read
device ID
Command
MSB 0x0B
Bit31:24
ID first byte
Bit23:16
ID second byte
Command
MSB 0x04
Bit15:8
ID third byte
Bit7:0
ID fourth byte

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4.11 AHS01IB sensor I2C register definition
Table 14 general table of register
Read sensor frame format: host frame format: (SLA+W)+ start address + register number +(SLA+R)+dela +
return data +CRC8
Write sensor frame format: host frame format: (SLA+W)+ start address + register number +(SLA+W)+ write
data +CRC8
List of sensor registers:
Register Adr Description Adr Description Adr Descriptio
n Adr
Humidit
MSB 0x00
device t pe MSB 0x08 Status LSB 0x10 Reserved 0x18
Humidit
LSB 0x01
device t pe LSB 0x09 Reserved 0x11 Reserved 0x19
Reserved 0x02 version 0x0A Reserved 0x12 Reserved 0x1A
Reserved 0x03 ID(24-31) Bit 0x0B Reserved 0x13 Reserved 0x1B
Reserved 0x04 ID(16-23) Bit 0x0C Reserved 0x14 Reserved 0x1C
Reserved 0x05 ID(8 - 15) Bit 0x0D Reserved 0x15 Reserved 0x1D
Start CMD 0x06 ID(0 - 7) Bit 0x0E Reserved 0x16 Reserved 0x1E
End CMD 0x07 Status MSB 0x0F Reserved 0x17 Reserved 0x1F
4.12 AHS01IB sensor CRC sample program
AHS01IB sensor CRC validation USES CRC8 with initial value of 0XFF and pol nomial of
0x31 (x8 + x5 + x4 + 1). Please see the code below for details