AK7735EQ Datasheet, PDF (90/142 Pages) Asahi Kasei Microsystems – Dual DSP with 4chADC + 4chDAC + 4chSRC

[AK7735]
■ Simple Write Error Check
The AK7735 have a cyclic redundancy check (CRC) function for a simple checking of writing data for
RAM and registers.
1. Checked Data
1-1. SPI Interface
SI data during CSN = “L” is checked.
• Serial Data D(x): SI data which is input during a period from a falling edge to a rising edge of CSN
• Generator Polynomial G(x)=x¹⁶+x¹²+x⁵+1 (Divisor=0x1021, Default=0, MSB-first, Not Inverted)
• The remainder of D(x) divided by G(x) is R(x).
1-2. I²C Interface
Command code, address and data from the second byte are checked. (Acknowledge is not included.
Therefore, the checked result will be the same as the SPI interface if the same command code, address
and data are written.) The first byte which includes a slave address is not checked. It can be checked by
Acknowledge.
• Serial Data D(x): Command Code, Address and Data (Slave Address is not included)
• Generator Polynomial G(x)=x¹⁶+x¹²+x⁵+1 (Divisor=0x1021, Default=0, MSB-first, Not Inverted)
• The remainder of D(x) divided by G(x) is R(x).
2. Simple Write Error Check Sequence
There are two ways to check write error.
2-1. CRC Result
(1) Write serial data D(x) to be checked.
(2) Read out a CRC result (remainder R(x)) by the command code 72H.
(3) Check the result by a microprocessor.
(4) When checking other serial data, repeat the sequence from (1) to (3).
Note
* 73. The internal CRC result is not updated by command code 72H.
2-2. STO pin State
(1) Set control register CRCE bit to “1”.
(2) Write serial data D(x) to be checked.
(3) Write the R(x) value to registers by the command code F2H.
(4) If the remainder of D(x) divided by G(x) is equal to R(x), the STO pin outputs “H”. If not, it outputs “L”.
(5) When checking other serial data, repeat the sequence from (2) to (4).
Note
* 74. The STO pin keeps outputting “L” until a correct value of R(x) is written in sequence (3).
016014707-E-00
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2016/12