AK9752 Datasheet, PDF (12/36 Pages) Asahi Kasei Microsystems – Ultra-small IR sensor IC with IC

[AK9752]
10.5. Read Measurement Data
When measurement data is stored and updated in the read-out register, DRDY bit of ST1 register
changes to “1”. This state is called “Data Ready”.
It can be also set up so that INTN outputs “L”, when the DRDY changes to “1”, by setting the interrupt
setting register INTEN.
By the either above ways, it can be confirmed whether Data Ready or not.
The read-out procedure is detailed as follows. (Single shot Mode is used as an example.)
10.5.1. Normal Read-out Procedure
(1) Read out ST1 register
DRDY: DRDY bit 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 when DRDY = “1”.
(2) Read out INTCAUSE register
Interrupt factors can be found out by reading out INTCAUSE register.
Refer to 13. Registers Functional Descriptions for details.
When starting reading-out of INTCAUSE register, measurement data are transferred to read-out
registers and retained. (Data protection)
INTN returns to “Hi-Z” after reading out INTCAUSE register.
(3) Read out measurement data
(4) Read out ST2 resister (Required Operation)
AK9752 recognizes that a data read-out has finished by read out the ST2 registers. Because
read-out registers are protected while reading out, data is not updated. Data protection of the
read-out registers is released by reading out the ST2 register. The ST2 register must be read out
after accessing read-out registers.
DOR: DOR bit shows whether there are any data which had not been read out before initiating
the current read.
DOR= “0” means that there are no data which had not been read out
before initiating the current read.
DOR= “1” means that there are data which had not been read out
before initiating the current read.
DRDY and DOR changes to “0” after reading out ST2 register.
Measurement
(N) th
Meas.
PD (Power down)
(N+1) th
Meas.
PD
(N+2) th
Meas.
PD
Internal Buffer (N-1)th data (N)th data
(N+1)th data
(N+2)th data
Read-out Register (N-1)th data (N)th data
(N+1)th data
(N+2)th data
DRDY(ST1)
DOR(ST2)
DRDY changes to "0" because Read-out Register
is not updated at read-out completion.
INTN output
SDA output
ST1 INTC (N)th data ST2
ST1 INTC (N+1)th data ST2
* INTC = INTCAUSE
Figure 10.4. Normal Read-out Procedure
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