User`s manual

Am186
TM
CC Microcontroller ISDN TA Reference Design Manual
2-8
ISDN S/T Interface
The Am79C32A IDC (ISDN data controller) circuit is used to provide the four-
wire 2B+D S/T interface. This device has a general circuit interface (GCI) or IOM-2
serial microprocessor interface, which is used to transfer B channel data to and
from the Am186CC microcontroller’s integrated HDLC controller. The Am186CC
communications controller-based ISDN TA reference design provides a full-
duplex path between the terminal equipment (TE) and the network termination
(NT) device. The controller processes the ISDN basic rate interface (BRI) bit
stream, which consists of two 64-kbps B channels and a single 16-kbps D channel.
The schematic for the S/T interface block is shown in Figure 2-5.
The Am79C32A IDC circuit includes a D-channel HDLC controller which is used
by software to send and receive data on the D channel.
The four-wire ISDN S/T interface is first directed through an S transformer and
line filtering devices These isolate and protect the modem from the outside lines.
The crystal is used to generate MCLK, which can be used as a master clock output
and as the system clock for the microprocessor.
The signals SBIN, SBOUT, SCLK, SFS, and BCL/CH2STRB can be configured
for serial bus port (SBP) or GCI. SBP is used by the current terminal adapter
software and is connected to HDLC Channel A on the Am186CC communications
controller.
Figure 2-5. ISDN TA S/T Interface
AD1
AD7
AD4
MA3
AD3
AD5
MA1
LIN1
LOUT1
MA2
LOUT2
AD2
AD6
AD0
LIN2
VCC5
U5
Pulse PE-65799
S Transformer
16
15
1
2
3
4
5
6
7
89
10
11
12
13
14
U4
AM79C32A PLCC
34 33
41
42
38
39
35 40
11
12
13
14
18
17
16
27
26
25
24
22
21
20
19
30
31
28
29
23
32
43
44
1
2
3
4
5
6
7
8
9
10
37
15
36
XTAL1 XTAL2
LIN2
LIN1
LOUT2
LOUT1
INT# HSW
RESET
CS#
RD#
WR#
A0
A1
A2
D0
D1
D2
D3
D4
D5
D6
D7
SCLK
SFS
SBIN
SBOUT
BCL/C2ST
MCLK
RSRVD
RSRVD
RSRVD
RSRVD
RSRVD
RSRVD
RSRVD
RSRVD
RSRVD
RSRVD
AVCC
DVCC
AVSS
DVSS
DVSS
X1
12.228MHz
1 2
P1
RJ45A
1
2
3
4
5
6
7
8
11
12
1
2
3
4
5
6
7
8
GND1
GND2
C25
680pF
C21
27pF
C20
27pF
C26
680pF
R11
100
0805
+/- 1%, 1/8W
R8
100
0805
+/- 1%, 1/8W
C76
1000pF
C78
1000pF
C75
1000pF
C77
1000pF
R110
2K
1206
R109 3.6K
1206
R111
3.6K
1206
R115
22.6
1210
+/- 1%, 1/2W
R114
22.6
1210
+/- 1%, 1/2W
R112
22.6
1210
+/- 1%, 1/2W
R113
22.6
1210
+/- 1%, 1/2W
R108
2K
1206
U6
PE65554
5
6
7
81
2
3
4
U16
LC03-6
1
2
3
4 5
6
7
8
U17
LC03-6
1
2
3
4 5
6
7
8
TXDA
CLKA
FSCA
RESOUT
AD[15..0]
PCS1#
RXDA
MA[19..0]
WR#
RD#
INT1
about.book Page 8 Friday, December 18, 1998 9:41 AM