AK7755EN_16 Datasheet, PDF (83/109 Pages) Asahi Kasei Microsystems – DSP with Mono ADC Stereo CODEC + Mic/Lineout Amp

[AK7755]
4. Acknowledgement Polling
The AK7755 cannot receive instructions while the RDY pin (Data Write Ready pin) is at low level.
The maximum transition time of the RDY pin from low level to high level is 2/fs (fs: sampling
frequency), but it is possible to confirm in a faster cycle that the RDY pin has become high by
checking the AK7755 internal condition, which is made by verifying the acknowledgement.
4-1. Generation of “Not Acknowledged”
The AK7755 does not accept command codes until the RDY pin is set to a high level, when a
command is received to set the RDY pin to a low level. In order to confirm the RDY pin condition, a
“Write Slave-Address assignment” should be sent after a Start condition. If the RDY pin is then at a
low level, “Acknowledgement” is not generated at the succeeding clock (generation of “Not
Acknowledged”). After sending “Not Acknowledged”, the BUS is released and all receiving data are
ignored until the next start condition (behaves as if it received Slave address of other device).
4-2. When Read Slave-address assignment is received without receiving read command code
Data read in the AK7755 can be made only in the previously documented Read sequence. Data cannot
be read out without receiving a read command code. The AK7755 generates a “Not Acknowledged”
when a “Read Slave-address Assignment” is received without proper receipt of read command.
5. Limitation in use of I²C Interface
The I2C interface does not support the following features.
No operation in Hs Mode (max:3.4MHz). The AK7755 Supports FAST mode (max:400KHz).
Note 54. Do not turn off the power of the AK7755 whenever the power supplies of other devices of the
same system are turned on. The source of the pull-up of SDA and SCL of I²C BUS must not
exceed the TVDD. (The diode exists for TVDD in the SDA and SCL pins.)
014006643-E-00
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2014/10