MC145572PB Freescale Semiconductor, MC145572PB Datasheet - Page 113

• Manufacturer Part Number: MC145572PB
• Manufacturer: Freescale Semiconductor

Specifications of MC145572PB

• Number Of Line Interfaces: 1
• Control Interface: HDLC
• Lead Free Status / Rohs Status: Not Compliant

MOTOROLA
6.3
6.4
6.5
ACTIVATION SIGNALS FOR LT MODE
When configured as an LT, the MC145572 U–interface transceiver can transmit any of the signals
shown in Table 6–2. The actual procedure undertaken by the device using these five signals is de-
scribed later in this chapter. Section 4.4.9 describes how to control the transmit framer when it is
desired to generate signals for test purposes.
ACTIVATION INITIATION
The MC145572 U–interface transceiver can be activated in either of two ways. The external microcon-
troller can explicitly issue Activation Request (NR2(b3) = 1) or the transceiver detects an incoming
10 kHz wake–up tone. An LT configured U–interface transceiver searches for an NT sending the TN
wake–up tone. An NT configured U–interface transceiver searches for an LT sending the TL wake–up
tone. In IDL2 mode, the Activation in Progress status bit (NR1(b0)) is set to a 1 when an incoming
10 kHz wake–up tone is detected. In either case, Activation Request being set or a wake–up tone
being detected, the U–interface transceiver proceeds with activation automatically and signals the
result of the activation to the external microcontroller by setting status bits in NR1 to $B.
An NT configured U–interface transceiver always initiates activation by sending a TN tone to the LT.
This is done in response to the LT sending a TL or when the Activation Request bit (NR2(b3)) is set
to a 1.
An LT configured U–interface transceiver initiates activation by sending the TL tone when the Activa-
tion Request bit is set to a 1 by an external microcontroller. The NT U–interface transceiver responds
to the TL tone by sending a TN tone back to the LT U–interface transceiver. Otherwise, the LT U–inter-
face transceiver waits for an unsolicited incoming TN tone from the NT U–interface transceiver and
self–activates. Regardless of how activation is initiated, the LT U–interface transceiver automatically
activates from the point where it detects the incoming TN tone from the NT transceiver.
When configured for MCU mode, all appropriate maintenance channel registers should be initialized
prior to setting Activation Request (NR2(b3)) or immediately after detecting Activation in Progress
(NR1(b0)) = 1. In GCI mode, the MC145572 automatically initializes the maintenance channel regis-
ters.
Some applications, such as U–repeaters, may require longer than 15 seconds of activation time. The
15–second activation timer can be disabled by setting Activation Timer Disable (BR11(b0)) to a 1.
ACTIVATION OF U-INTERFACE BY NT
NT mode activation initiation is accomplished by setting Activation Request (NR2(b3)) to a 1. The
NT U–interface transceiver initiates activation of the U–interface by transmitting TN for a time period
of six frames (9 ms) toward the LT. At this time, the NT U–interface transceiver also sets Activation
in Progress (NR1(b0)) to a 1. Transmission of TN is immediately followed by transmission of SN1
while the echo cancellers are trained.
From Figure 6–1, it can be seen that the NT transceiver has a period of time during activation where
the LT end is guaranteed to be quiet. This is to permit the MC145572 to train its echo cancellers during
the transmission of SN1.
Information
Station
SL0
SL1
SL2
SL3
TL
A 10 kHz tone consisting of alternating four + 3 quats followed by four – 3 quats for a time period of two frames.
No signal transmitted.
Synchronization word present, no Superframe Synchronization word (ISW), and 2B+D+M = 1.
Synchronization word present, Superframe Synchronization word (ISW) present, 2B+D = 0, and M = Normal.
Synchronization word present, Superframe Synchronization word (ISW) present. M channel bits active.
Transmitted 2B+D data operational when M4 act bit = 1. When M4 act = 0, transmitted 2B+D data = 0.
Freescale Semiconductor, Inc.
For More Information On This Product,
Table 6–2. LT Mode Activation Signals
Go to: www.freescale.com
MC145572
Description
6–3