Specifications

Si2404

Rev. 0.91 37

User-Access Registers (U-Registers)

The :U AT command is used to write these 16-bit U-registers, and the :R command is used to read them.

U-registers are identified by a hexidecimal (hex) address.

Table 15. U-Register Description

U00 DT1A0 DT1 registers set the coefficients for stage 1 of the Dial Tone Detect filter.

Default is for FCC countries. See “AN93: Modem Designer’s Guide” for other

country settings.

0x0800

U01 DT1B1 0x0000

U02 DT1B2 0x0000

U03 DT1A2 0x0000

U04 DT1A1 0x0000

U05 DT2A0 Dial tone detect filters stage 2 biquad coefficients. 0x00A0

U06 DT2B1 0x6EF1

U07 DT2B2 0xC4F4

U08 DT2A2 0xC000

U09 DT2A1 0x0000

U0A DT3A0 Dial tone detect filters stage 3 biquad coefficients. 0x00A0

U0B DT3B1 0x78B0

U0C DT3B2 0xC305

U0D DT3A2 0x4000

U0E DT3A1 0xB50A

U0F DT4A0 Dial tone detect filters stage 4 biquad coefficients. 0x0400

U10 DT4B1 0x70D2

U11 DT4B2 0xC830

U12 DT4A2 0x4000

U13 DT4A1 0x80E2

U14 DTK Dial tone detect filter output scaler. 0x0009

U15 DTON Dial tone detect ON threshold. 0x00A0

U16 DTOF Dial tone detect OFF threshold. 0x0070