RCVDL56DPFL/SP, RCV56DPFL/SP, and RCV336DPFL/SP Designer’s Guide
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4-33
Function 85:
V.34 Data Rate Mask
Acc Method: 2
Address: 383h, 382h
K56flex/V.34 Transmitter Maximum Data Rate Mask Acc Method: 1
Address: 605h
K56flex/V.34 Receiver Maximum Data Rate Mask
Acc Method: 1
Address: 604h
The V.34 data rate masks occupy two bytes in RAM. Locations 382h and 383h represent the lower byte and the upper byte
of the mask, respectively (Table 4-7). The bits in the mask represent the enabling of a particular data rate if set or disabled if
reset. The definition of the bits are data rate 2400 is at bit 0 (i.e., the LSB of address 382h), 4800 is at bit 1, 7200 at bit 2
and so on up to 33600 bps (in 2400 bps increments) which is bit 13 of the mask (or bit 5 of address 383h. Bits 14-15 are
reserved.
Table 4-7. V.34 Rate Sequence Mask Bit Assignments
Data Rate
V.34 Data Rate Mask-MSB (Address 383h)
V.34 Data Rate Mask-LSB (Address 382h)
(bps)
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
2400
-
-
X
X
X
X
X
X
X
X
X
X
X
X
X
1
4800
-
-
X
X
X
X
X
X
X
X
X
X
X
X
1
X
7200
-
-
X
X
X
X
X
X
X
X
X
X
X
1
X
X
9600
-
-
X
X
X
X
X
X
X
X
X
X
1
X
X
X
12000
-
-
X
X
X
X
X
X
X
X
X
1
X
X
X
X
14400
-
-
X
X
X
X
X
X
X
X
1
X
X
X
X
X
16800
-
-
X
X
X
X
X
X
X
1
X
X
X
X
X
X
19200
-
-
X
X
X
X
X
X
1
X
X
X
X
X
X
X
21600
-
-
X
X
X
X
X
1
X
X
X
X
X
X
X
X
24000
-
-
X
X
X
X
1
X
X
X
X
X
X
X
X
X
26400
-
-
X
X
X
1
X
X
X
X
X
X
X
X
X
X
28800
-
-
X
X
1
X
X
X
X
X
X
X
X
X
X
X
31200
-
-
X
1
X
X
X
X
X
X
X
X
X
X
X
X
33600
-
-
1
X
X
X
X
X
X
X
X
X
X
X
X
X
The rate mask at 383h/382h controls the data rate for both the transmitter and receiver. In other words, if the rate mask is
limited to 24k bps, both the transmitter and receiver rates will be limited to 24k bps. If connected in asymmetric mode (see
Function 86) the transmitter rate may be further limited by the request of the remote modem's receiver. In symmetric mode,
the transmitter and receiver rates cannot differ and will end up at the highest common rate between the two modems, at or
below the maximum common data rate specified in both modem's rate mask.
The transmitter and receiver rates can alternatively be limited independently through addresses 605h and 604h, respectively.
Note that only the maximum rate can be limited and not specific rates as with the mask at 383h/382h. See Section 14.
The rate masks will limit the data rates during the initial handshake, retrains and rate renegotiations. The rate masks will also
limit (but not increase) any speed decision made by the ARA or the manual data rate selection as described in Section 14.
Function 86:
K56flex/V.34 Asymmetric Data Rates Enable
Acc Method: 1
Address: 13Fh:6
V.34 modes normally operate with asymmetric data rates for the transmitter and receiver. Resetting (default state) bit
13Fh:6 (Function 85) forces the transmitter and receiver data rates to be the same. Setting bit 13Fh:6 allows the transmitter
data rate to be different than the receiver data rate. Note: This bit must be set in K56flex.
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