mt9079apr1 Zarlink Semiconductor, mt9079apr1 Datasheet - Page 53

• Manufacturer Part Number: mt9079apr1
• Description: Advanced Controller For E1
• Manufacturer: Zarlink Semiconductor

The MC68302 watch-dog timer must be reset periodically or the WDOG output will go low for 16 microprocessor
clock cycles (CLKO) and return high. In the circuit of Figure 11 this will reset the MC68302 and turn on the transmit
AIS of all the MT9079 devices through the 74HCT74 flip-flops. The transmit AIS will not terminate until the
MC68302 reset command has been executed to clear the 74HCT74 flip-flops.
Provision has been provided to initiate the transmission of AIS on individual MT9079 devices from a control port.
This function can also be accomplished by writing to the Transmit Alarm Control Word of the MT9079.
Interface Initialization
Figure 12 is a flow chart that illustrates the basic steps involved in initializing the MT9079 from a power-on state.
The post reset state of each control bit will determine which flow chart steps may be left out in specific applications.
The first step is to make TAIS low so the MT9079 will transmit an all 1’s signal during the initialization procedure.
This informs the remote end of the E1 link that this end is not functioning normally. After the RESET cycle is
complete all interrupts are suspended so the microprocessor will not jump to any interrupt service routines until the
interface is configured. It is important to write 00H to all the per-timeslot control words (pages 7 and 8) so that
transmit timeslots are not substituted with unknown data. Next the mode of operation and timing can be selected.
IN4148
IN4148
+5V
1M
0.1 F
R
C
+5V
+5V
V
10k
R
74HCT14
TH
RS
TR
CV
MC1455
MT9079
Figure 11 - MT9079 Reset and Transmit AIS Circuit
POR
DIS
O
+5V
1M
0.47 F
to Control Port
to Control Port
to Control Port
Zarlink Semiconductor Inc.
74HCT05
74HCT05
.
.
.
.
MT9079
+5V
+5V
74HCT11
74HCT11
74HCT11
12k
4.7k
53
HALT
RESET
MC68302
TAIS
RESET
TAIS
RESET
TAIS
RESET
MT9079
MT9079
MT9079
WDOG
.
.
.
.
74HCT05
74HCT05
PCM 30
Trunk 0
PCM 30
Trunk 1
PCM 30
Trunk n
+5V
74HCT05
74HCT05
4.7k
74HCT32
+5V
4.7k
74HCT74
D
CLR
PR
Q
Q
+5V
Data Sheet
4.7k
D
CLR
PR
Q
Q