General Circuit Interface (GCI)
17-16
Am186™CC/CH/CU Microcontrollers User’s Manual
17.5.7.5
TIC Bus Support
The meaning of each bit within the TIC bus is dependent on whether the Am186CC
microcontroller is transmitting or receiving on the TIC bus. Table 17-5 lists and describes
the TIC bus bits.
In the downstream direction (from the transceiver), the TIC bus on GCI Subframe 2 is used
for D and C/I0 channel access control in S/T interface terminals.
The TIC bus downstream has the format shown in Figure 17-8.
Figure 17-8
TIC Bus Downstream Format
The availability of the S/T interface D-channel is indicated in bit 5 (Stop/Go bit) of the
downstream TIC bus. The Am186CC microcontroller GCI TIC bus controller checks the
Stop/Go bit to determine if it has access to the D-channel. If it does, it can start transmission
of an HDLC frame. If the TIC bus controller does not have access, it must halt the
transmission. Bits 7 and 6 are the D-channel Echo bits from the S-interface (reflecting back
the two D-channel bits of the current frame). The Am186CC microcontroller GCI TIC bus
controller compares the Echo bits with the sent D-channel bits to determine if a collision
has occurred. A D-channel collision is reported to an HDLC through an internal signal,
originating from the GCI TIC bus controller, whose function is similar to an external CTS
deassertion (a mechanism that stops HDLC transmission). The Am186CC microcontroller
does not use the A/B bit.
In the upstream direction (to the transceiver), the TIC bus on GCI Channel 2 is used for the
TIC bus access procedure, enabling the connection of several Layer 2 D-channel protocol
controllers to the GCI interface.
The TIC bus upstream has the format shown in Figure 17-9.
Figure 17-9
TIC Bus Upstream Format
Table 17-5
TIC Bus Bits
Bit Name
Bit Function
BAC (Bus Accessed)
Indicates to the other devices that the TIC bus is being accessed. When 0, the
bus is being accessed; when 1, it is free. This bit is driven to zero by the device
that gets an address match on TBA2–TBA0.
TBA2-0 (TIC Bus Address)
Address bit used for arbitration of TIC bus control. Assumes open-drain bus
such that the device with the lowest address has the highest priority. The lowest
priority address, which is also the default, is 111.
E-bits (Echo Bits)
D-channel Echo bits from the S-interface.
S/G bit (Stop/Go)
Indicates availability of the S-interface D-channel. When 0, the D-channel is
clear for transmission. When 1, D-channel transmission should be halted.
Bit Number
7
6
5
4
3
2
1
0
Bit Name
E
E
S/G
A/B
1
1
1
1
Bit Number
7
6
5
4
3
2
1
0
Bit Name
1
1
BAC
TBA2
TBA1
TBA0
1
1
Содержание Am186 CC
Страница 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
Страница 4: ...iv Am186 CC CH CU Microcontrollers User s Manual...
Страница 18: ...Table of Contents xviii Am186 CC CH CU Microcontrollers User s Manual...
Страница 24: ...Introduction xxiv Am186 CC CH CU Microcontrollers User s Manual...
Страница 39: ...Architectural Overview Am186 CC CH CU Microcontrollers User s Manual 1 15 Figure 1 6 32 Channel Linecard CH CC...
Страница 40: ...Architectural Overview 1 16 Am186 CC CH CU Microcontrollers User s Manual...
Страница 86: ...System Overview 3 36 Am186 CC CH CU Microcontrollers User s Manual...
Страница 92: ...Emulator Support 4 6 Am186 CC CH CU Microcontrollers User s Manual...
Страница 112: ...DRAM Controller 6 8 Am186 CC CH CU Microcontrollers User s Manual...
Страница 134: ...Interrupts 7 22 Am186 CC CH CU Microcontrollers User s Manual...
Страница 186: ...Programmable I O Signals 9 8 Am186 CC CH CU Microcontrollers User s Manual...
Страница 200: ...Watchdog Timer 11 6 Am186 CC CH CU Microcontrollers User s Manual...
Страница 232: ...Asynchronous Serial Ports UARTs 13 24 Am186 CC CH CU Microcontrollers User s Manual...
Страница 242: ...Synchronous Serial Port SSI 14 10 Am186 CC CH CU Microcontrollers User s Manual...
Страница 264: ...High Level Data Link Control HDLC 15 22 Am186 CC CH CU Microcontrollers User s Manual...
Страница 332: ...Universal Serial Bus USB 18 34 Am186 CC CH CU Microcontrollers User s Manual...
Страница 348: ...Register Summary A 16 Am186 CC CH CU Microcontrollers User s Manual...
Страница 376: ...Index Index 18 Am186 CC CH CU Microcontrollers User s Manual...