STA382BWSTR datasheet(101/172 Pages) STMICROELECTRONICS

101 / 172 page

STA382BWS

Doc ID 022784 Rev 1

101/172

The STA382BWS implements an automatic CRC computation for the biquad and

MDRC/XOver coefficient memory (Table 74). Memory cell contents from address 0x00 to

0x27 will be bit XORed to obtain the BQCHKE checksum, while cells from 0x28 to 0x31 will

be XORed to obtain the XCCHKE checksum. Both checksums (24-bit wide) are exported on

I2C registers from 0x60 to 0x65. The checksum computation will start as soon as the BCGO

(for biquad RAM bank) or the XCGO bit (for MDRC/XOver coefficients) is set to 1. The

checksum is computed at the processing sample rate if the IR bits equal “01” or “10”,

otherwise the checksum is computed to half of the processing sample rate.

When BCCMP or XCCMP is set to ‘1’, the relative checksum (BQCHKE and XCCHKE) is

continuously compared with BQCHKR and XCCHKR respectively. If the checksum matches

its own reference value, the respective result bits (BCRES and XCRES) will be set to ‘0’.

The compare bits have no effect if the respective GO bit is not set.

In case of checksum errors (i.e. the internally computed didn’t match the reference), an

automatic device reset action can be activated. This function is enabled when the BCAUTO

or XCAUTO bit is set to ‘1’. The automatic reset bits have no effect if the respective compare

bits are not set.

The recommended procedure for automatic reset activation is the following:

●

Download the set of coefficients (RAM locations 0x00…0x27)

●

Download the externally computed biquad checksum into registers BQCHKR

●

Enable the checksum of the biquad coefficients by setting the BCGO bit. The

checksum will start to be automatically computed by the STA382BWS and its value

exposed on registers BQCHECKE. The checksum value is computed and updated.

●

Enable the checksum comparison by setting the BCCMP bit. The internally computed

checksum will start to be compared with the reference one and the result will be

exposed on the BCRES bit. The following operation will be executed on each audio

frame:

if ((BQCHKE == BQCHKR))

{

BC_RES = 0;// Checksum is ok, reset the error bit

}

XCAUTO

XCRES

XCCMP

XCGO

BCAUTO

BCCRES

BCCMP

BCCGO

Obsolete

Product(s)

- Obsolete

Product(s)

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