AK9720 Datasheet, PDF (19/31 Pages) Asahi Kasei Microsystems – IR Sensor Module with I2C I/F

[AK9720]
5. Data Ready
When measurement data is stored to the measurement data registers, the DRDY bit of
the ST1 register changes to “1”. This state is called “Data Ready”. It can be set up so that
the INT pin outputs "High", when the DRDY bit is "1", by setting up the interruption register.
Read-out procedure is detailed here. (Single shot Mode is is used as an example.)
The same procedure can also be applied to the Continuous Measurement Mode1 and
Continuous Measurement Mode2.
5.1 Normal Read-out Procedure
(1) Read-out ST1 registers
DRDY: DRDY shows whether the state is “Data Ready” or not.
DRDY ="0" means “No Data Ready”.
DRDY ="1" means “Data Ready”.
DOR: DOR shows whether there are any data which was not read out before initiating
the current read.
DOR="0" means that there are no data which was not read out before initiating
the current read.
DOR="1" means that there are data which was not read out before initiating the
current read.
(2) Read the measurement data
Once a data read is initiated fromone of the measurement data registers (IRSL to TMPH)
or the ST2 register, the AK9720 recognizes that a data read-out has begun. When a data
read-out is initiated, DRDY and DOR change to “0”.
(3) Read ST2 Resisters (Required Operation)
The AK9720 recognizes that a data read-out has finished by reading out the ST2 registers.
Because the measurement data registers are protected while reading out, data is not
updated. Data protection of the measurement data register is canceled by reading out the
ST2 register. The ST2 register must be read out after accessing the measurement data
register.
(N-1) (N)
(N+1)
PD _Measurement
PD
Measurement
PD
Measurement data register
data(N-1)
data(N)
data(N+1)
DRDY
Read-out data
ST1 data(N)
ST2
ST1 data(N+1)
ST2
Fig.6. Normal Read-out Procedure
Rev.02
AKM Confidential
- 19 -
2012/11