A N 9 3
98
Rev. 1.4
5.7. U Registers
U registers (user-access registers) are 16-bit registers written by the AT:Uhh command and read by the AT:R (read
all U registers) command or AT:Rhh (read U-register hh) command. See the AT command list in Table 49 on
page 64. All values associated with the U registers, the address, and the value written to or read from the register
are hexadecimal.
Some U registers are reserved and not available to the user. Therefore, there are gaps in the available U-register
address sequence. Additionally, some bits within available U registers are reserved. Any attempt to write to a non-
listed U register or to write a reserved bit can cause unpredictable modem operation.
There are two types of U registers. The first represents a single 16-bit term, such as a filter coefficient, threshold,
delay, or other quantity. These registers can be read from or written to as a single 16-bit value. The second type of
U register is bit mapped. Bit-mapped registers are also written and/or read in hexadecimal, but each bit or
combination of bits in the register represents an independent value. These individual bits are used to enable or
disable features and indicate states. Bits in these registers can be read/write, read only, reserved, or they may be
required to always be set to a certain value. Pay particular attention when writing to bit-mapped registers to ensure
no reserved bits are overwritten. When changing bits in a U register with reserved bits, use a read-modify-write
procedure: read the register value with AT:R; modify only the desired bits, then write the new value with AT:U. This
will ensure the reserved bits are not altered. All U registers revert to their default settings after a reset.
The U registers can be broken into three groups: call progress (U0–U33, U49–U4C), dialing (U37–U48), line
interface, and extended functions (U4D–UA9). Table 57 lists the available U registers, a brief description, and their
default values. Table 58 summarizes the signals and values available in the bit-mapped registers. Country-specific
register values are presented in "6.2. Country-Dependent Setup" on page 145. All default settings are chosen to
meet FCC requirements.
Table 57. U-Register Descriptions
Register
Name
Description
Default
Value
U00
DT1A0
Dial-tone detection filters stage 1 biquad coefficients.
0x0800
U01
DT1B1
0x0000
U02
DT1B2
0x0000
U03
DT1A2
0x0000
U04
DT1A1
0x0000
U05
DT2A0
Dial-tone detection filters stage 2 biquad coefficients.
0x00A0
U06
DT2B1
0x6EF1
U07
DT2B2
0xC4F4
U08
DT2A2
0xC000
U09
DT2A1
0x0000
U0A
DT3A0
Dial-tone detection filters stage 3 biquad coefficients.
0x00A0
U0B
DT3B1
0x78B0
U0C
DT3B2
0xC305
U0D
DT3A2
0x4000
U0E
DT3A1
0xB50A
Содержание Si2404
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Страница 27: ...AN93 Rev 1 4 27 Figure 7 Parallel Interface Read Timing Figure 8 Parallel Interface Write Timing ...
Страница 200: ...AN93 200 Rev 1 4 Figure 31 TAM Handset and Speakerphone Voice Paths ...
Страница 201: ...AN93 Rev 1 4 201 Figure 32 Si3000 Codec Gain and Signal Selection Options ...
Страница 290: ...AN93 290 Rev 1 4 Figure 57 256 Band Spectral Display Figure 58 2048 Band Spectral Display ...
Страница 305: ...AN93 Rev 1 4 305 Figure 76 Parallel or SPI Port Interrupt Service Flowchart ...