AK7746 Datasheet, PDF (42/62 Pages) Asahi Kasei Microsystems – Audio DSP with 5-channel 24-bit ADC and Input Mux

[ASAHI KASEI]
(7) Interface with microcomputer
[AK7746]
The microcomputer interface uses 6 control pins; RQ (ReQuest Bar), SCLK (Serial data input Clock), SI (Serial data Input), SO
(Serial data Output), RDY (ReaDY) and DRDY (Data ReaDY).
In the AK7746, two types of operations are provided; writing and reading during the reset phase (system reset) and R/W during the
run phase. During the reset phase, writing of the control register, program RAM, coefficient RAM, offset RAM, external conditional
jump code, and reading of the program RAM, coefficient RAM and offset RAM are enabled. During the run phase, writing of
coefficient RAM, offset RAM and external conditional jump code, and reading of data on the DBUS (data bus) from the SO, are
enabled. Its data is MSB first serial I/O.
When the AK7746 transfers data to the microcomputer, it starts by RQ going “L” (Expects when reading the data on the DBUS).
The AK7746 reads data at the rising point of SCLK from the SI pin, and outputs data on the falling edge of SCLK to the SO pin.
The AK7746 first data is command code and then address data for the data input / output to start.
When RQ changes to “H”, one command has finished. For a new command requests, set RQ to “L” again. For DBUS data reads,
leave RQ =”H”. (It does not need command code input.) To clear the output buffer (MICR), the SI pin is used. (In this case, it is
necessary to protect against a noise as SCLK.)
The Command code table is as follows.
Conditions
for use
RESET
phase
RUN
phase
Code name
CONT0
CONT1
CONT2
CONT3
CONT4
CONT5
PRAM
CRAM
OFRAM
External condition jump
CRC check (R(x))
(CONT1~CONT7)
CONT3
CRAM rewrite preparation
CRAM rewrite
OFRAM rewrite preparation
OFRAM rewrite
External condition jump
CRC check (R(x))
Command code list
Command code
Remark:
WRITE
READ
60h
70h
For the function of each bit,
62h
72h
See the description of Control Registers.
64h
74h
66h
76h
68h
78h
6Ah
7Ah
C0h
C1h
A0h
90h
C4h
B6h
(Note 1)
66h
A8h
A4h
98h
94h
A1h
91h
-
D6h
7Xh
76h
Only CONT3 can use
-
It needs to do before CRAM rewrite
-
-
It needs to do before OFRAM rewrite
-
C4h
-
Same code as RESET
B6h
D6h
Same code as RESET
NOTE: Do not send other than the above command codes. Otherwise an operation error may occur.
If there is no communication with the microcomputer, set the SCLK to "H” and the SI to "L" for use.
Note 1) It is recommended that CONT1~CONT7 registers are also only written to at a system reset to avoid any unwanted noise.
However, the CONT3 analog switch selectors can change during runtime.
[ See. 8. (2) Control registers. ]
[MS0369-E00]
- 42 -
2004/12