General Circuit Interface (GCI)
17-14
Am186™CC/CH/CU Microcontrollers User’s Manual
17.5.5.2
GCI-to-PCM Converted Pin Interface
The converted GCI to PCM interface consists of two pins. This interface (external interface C
on the Am186CC microcontroller) uses the signals listed in Table 17-4. For more information
about frame sync and clock conversion, see Chapter 16, “HDLC External Serial Interface
Configuration (TSAs).”
17.5.6
Operating Frequencies
GCI_DCL_A is used to clock data on and off of the bus, and it operates at twice the data rate.
The clock rate is 1.536 MHz (the data rate is 768 KHz). GCI_DCL_A is always generated
by the upstream component. When the bus is deactivated, GCI_DCL_A is held in a Low
state by the upstream device.
GCI_FSC_A is an 8-KHz clock that indicates the start of a frame. GCI_FSC_A is always
generated by the upstream device, which is the Layer 1 device in terminal applications.
17.5.7
GCI Channels
The GCI channels consist of three voice/data channels (B1, B2, and D), two monitor
channels (Mon0 and Mon1), two command/indication channels (C/I0 and C/I1), two
Interchip Communication channels (IC1 and IC2), and the TIC bus.
17.5.7.1
GCI HDLC Channel Steering
All HDLC channel data steering is provided through proper TSA (Time Slot Assigner) and
MUX initialization. While there is nothing to prevent an HDLC channel from accessing any
set of contiguous bits within the GCI frame, only accesses to the B, D, and IC channels are
guaranteed.
For more information about TSA configuration, see Chapter 16, “HDLC External Serial
Interface Configuration (TSAs).”
17.5.7.2
Monitor Channel Operation
The monitor channel is full duplex and operates on a pseudo-asynchronous basis, that is,
while data transfers on the bus take place synchronized to frame sync, the flow of data is
controlled by a handshake procedure using the MX (monitor transmit) and MR (monitor
receive) bits. For example, data is placed onto the monitor channel and the MX bit is
activated. This data is transmitted repeatedly (once per 8-KHz frame) until the transfer is
acknowledged through the MR bit. Thus, the data rate is not 8 Kbyte per second. Am186CC
microcontroller monitor channel support is provided on a one-at-a-time basis (the MCHSEL
bit in the GPCON register designates which monitor channel is selected). For a detailed
description of the monitor channel handshake procedure, see the AMD
IOM-2 Interface
Reference Guide, order #12576.
17.5.7.3
Monitor Channel Collision Detection
For multidrop configurations, a collision resolution mechanism is implemented in the Monitor
Channel transmitter that looks for the idle phase of the transmitted MX/MR bits and makes
a per bit check on the
transmitted monitor data.
Table 17-4
Converted GCI Signals
External Signal
Function
PCM_CLK_A
Converted GCI to PCM data clock
PCM_FSC_A
Converted GCI to PCM frame synchronization clock
Summary of Contents for Am186 CC
Page 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
Page 4: ...iv Am186 CC CH CU Microcontrollers User s Manual...
Page 18: ...Table of Contents xviii Am186 CC CH CU Microcontrollers User s Manual...
Page 24: ...Introduction xxiv Am186 CC CH CU Microcontrollers User s Manual...
Page 40: ...Architectural Overview 1 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 86: ...System Overview 3 36 Am186 CC CH CU Microcontrollers User s Manual...
Page 92: ...Emulator Support 4 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 112: ...DRAM Controller 6 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 134: ...Interrupts 7 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 186: ...Programmable I O Signals 9 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 200: ...Watchdog Timer 11 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 232: ...Asynchronous Serial Ports UARTs 13 24 Am186 CC CH CU Microcontrollers User s Manual...
Page 242: ...Synchronous Serial Port SSI 14 10 Am186 CC CH CU Microcontrollers User s Manual...
Page 264: ...High Level Data Link Control HDLC 15 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 332: ...Universal Serial Bus USB 18 34 Am186 CC CH CU Microcontrollers User s Manual...
Page 348: ...Register Summary A 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 376: ...Index Index 18 Am186 CC CH CU Microcontrollers User s Manual...