General Circuit Interface (GCI)
Am186™CC/CH/CU Microcontrollers User’s Manual
17-15
To access the monitor channel through Upstream Monitor Channel Collision Detection on
the first byte and Downstream Device Recognition on the first byte (these procedures are
used in Monitor Channel multidrop configurations), use the following procedures.
17.5.7.3.1
Upstream Monitor Channel Data Transmission
The address of the monitor message contained in the first monitor byte transmitted
determines the monitor channel access priority. The following hardware/software procedure
is followed:
1. Software configures the monitor channel for data transmission.
2. Hardware waits for the idle phase before transmitting the first byte of monitor data.
3. During the first byte transmitted, a per bit check occurs on each transmitted monitor bit.
If any bit mismatches, the transmitter immediately withdraws from the monitor channel
by setting all remaining monitor bits to 1 (thus allowing another device with higher priority
to gain control of the monitor channel), sets the monitor channel collision detection
interrupt, and reverts back to waiting for the idle condition.
Note: The collision detection interrupt is set on any monitor data transmit bit mismatch
(i.e., from the first byte transmitted to the last byte transmitted). Therefore, if software wishes
to differentiate how it services other byte collisions from first-byte collisions, it must maintain
this knowledge itself.
17.5.7.3.2
Downstream Monitor Channel Data Reception
Device recognition allows a downstream device to determine whether or not it is the intended
target for an initiated Monitor Channel message sent by an upstream device (the address
to be recognized is contained in the first byte of the monitor message). The following
hardware/software procedure is followed:
1. Hardware waits for the idle phase.
2. After detecting the idle phase, hardware waits for a valid first byte to be sent by an
upstream device.
3. After receiving the first byte, hardware indicates to software, through a data-available
interrupt, that the first byte has arrived.
4. Software determines whether or not the microcontroller was the intended target.
5. If a valid address is recognized (from the first byte), software indicates to the receiver
to continue with data reception by setting a valid address-compare bit. Otherwise,
software indicates to the receiver that it should not continue receiving data (through a
software-abort bit).
17.5.7.4
C/I Channel Operation
The C/I channel communicates real-time status information and maintenance commands.
Unlike the monitor channel, the Am186CC microcontroller supports both C/I channels
contained in GCI Subframe 0 and GCI Subframe 1 concurrently. Software reads the
received data from one of the C/I Receive Data (GCIRD0 or GCIRD1) registers. Software
writes C/I transmit data to one of the C/I Transmit Data (GCITD0 or GCITD1) registers. The
GCI controller monitors these two channels, and generates an interrupt any time the receive
data changes and is stable for two frames (GCI’s standard data integrity check). Data on
the C/I channel is continuously transmitted in each frame until new data is to be sent. In
this way, the C/I channel can be thought of as a set of static status lines that only change
when the status changes. For a list of C/I codes (for GCI Subframe 0 only), and further C/I
channel operation, refer to the AMD
IOM-2 Interface Reference Guide, order #12576.
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...