AK9750 Datasheet, PDF (19/49 Pages) Asahi Kasei Microsystems – IR Sensor IC with I2C I/F

[AK9750]
11.5 Read Measurement Data
When a measurement data is stored to the measurement register, DRDY bit of ST1 register changes to
“1”. This state is called “Data Ready”. It can be set up so that INT output “H”, when the DRDY bit is “1”,
by setting up the interruption register.
The read-out procedure is detailed here. (Single shot Mode is used as an example.)
The same procedure can also be applied the Continuous Mode 0 (1, 2, and 3).
11.5.1. 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”.
It is recommended that measurement data is read-out with DRDY = “1”.
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) Reading measurement data
Once a data read is initiated from one of the measurement data registers (IR1L to TMP) or the ST2
register, the AK9750 recognizes that a data read-out has begun. When a data read-out is initiated,
DRDY and DOR change to “0”.
(3) Reading ST2 Resisters (Required Operation)
The AK9750 recognizes that a data read-out has finished out the ST2 registers. Because the
measurement data registers are protected while reading out, data is not updated. Data protection of
the measurement data registers is canceled by reading out the ST2 register. The ST2 register must
be read out after accessing the measurement data register.
(N-1) (N)
PD Measurement
PD
Internal Buffer
data(N-1)
data(N)
Measurement data register
data(N-1)
data(N)
(N+1)
Measurement
PD
data(N+1)
data(N+1)
DRDY
Read-out data
ST1 ^data(N)
ST2
ST1 ^data(N+1) ST2
Figure 11.6. Normal Read-out Procedure
015002896-E-01
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2015/10