ST Sound Termina STA382BWTR, Manual, Page: 101 / 172

STA382BW Register description: New Map
Doc ID 022783 Rev 1 101/172
The STA382BW 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
I
2
C 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 STA382BW 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
}
0 0 0 0 0 0 0 0
D7 D6 D5 D4 D3 D2 D1 D0
XCAUTO XCRES XCCMP XCGO BCAUTO BCCRES BCCMP BCCGO
0 0 0 0 0 0 0 0
D7 D6 D5 D4 D3 D2 D1 D0
Obsolete Product(s) - Obsolete Product(s)