Specifications

AN93
84 Rev. 0.9
3.3.25. U53 (Modem Control Register 2)
U53 (MOD2) is a bit-mapped register with all bits,
except bit 15, reserved (see Table 52). The AT&H11
command sets the V.23 1200/75 bps mode. Bit 15
(REV) is used to enable V.23 reversing. This bit is set to
0
b
(disable reversing) by default. Setting this bit to 1
b
enables reversing transmit and receive speeds.
Reversing is initiated by the modem in the “origination
mode” (low speed TX and high speed RX). U53 resets
to 0x0000 with a power-on or manual reset.
3.3.26. U54 (CALT)
U54 (CALT) sets the time between off-hook and DAA
calibration if timed calibration is enabled with the TCAL
bit (U7D, bit 12). The OHCT bits (15:8) control this
timing in 32 ms units.
3.3.27. U62 (DAAC1)
U62 (DAAC1) is a bit-mapped register with only bits 1,
2, and 8 available. All other bits in this register are
reserved and must be set according to Table 49. U62
resets to 0x0804 with a power-on or manual reset.
Bit 1 (DL) = 1 or 0 causes digital loopback to occur
beyond the isolation capacitor interface out to and
including the analog hybrid circuit. Setting bit 1 to 1
enables digital loopback across the isolation barrier
only. This setting is used in conjunction with the AT&H
and AT&T3 commands. DL must be set to “0” for normal
operation.
Bit 2 (FOH) controls when automatic Si3018/10
calibration takes place.
Table 47. U53 Bit Map
Bit Name Function
15 REV V.23 Reversing.
0 = Disable.
1=Enable.
14:0 Reserved Read returns zero.
Table 48. U54 Bit Map
Bit Name Function
15:8 OHCT
Off-hook to calibration timing in 32 ms units. If enabled with TCAL (U7D bit 12), this value
controls the time between off-hook and DAA calibration.
7:0 Reserved Must be set to zero.
Table 49. U62 Bit Map
Bit Name Function
15:12 Reserved Must be set to zero.
11 Reserved Must be set to one.
10:9 Reserved Must be set to zero.
8OHS2On-Hook Speed 2.
This bit, in combination with the OHS bit and the SQ[1:0] bits on-hook speeds specified
are measured from the time the OH bit is cleared until loop current equals zero.
OHS OHS2 SQ[1:0] Mean On-Hook Speed
0 0 00 Less than 0.5 ms
0 1 00 3 ms ±10% (meets ETSI standard)
1 X 11 26 ms ±10% (meets Australia spark quenching spec)
Note: The +GCI command does not modify OHS2, SQ[1:0].
7:3 Reserved Must be set to zero.
2 FOH 0 = Automatic calibration timer set to 426 ms.
1 = Automatic calibration timer set to 106 ms.
1DL0 = Digital loopback beyond ISOcap™ interface.
1 = Digital loopback across ISOcap interface only.
0 Reserved Must be set to zero.