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參數(shù)資料
| 型號： | AM85C30-8 |
| 廠商： | Advanced Micro Devices, Inc. |
| 英文描述： | Enhanced Serial Communications Controller |
| 中文描述： | 增強的串行通信控制器 |
| 文件頁數(shù)： | 25/68頁 |
| 文件大?。?/td> | 553K |
| 代理商： | AM85C30-8 |
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AMD
25
Am85C30
FIFO
FIFO Enhancements
When used with a DMA controller, the Am85C30 Frame
Status FIFO enhancement maximizes the ESCC’s abil-
ity to receive high-speed back-to-back SDLC messages
while minimizing frame overruns due to CPU latencies
in responding to interrupts.
Additional logic was added to the industry-standard
NMOS SCC consisting of a 10-deep by 19-bit status
FIFO, a 14-bit receive byte counter, and control logic as
shown in Figure 13. The 10
×
19 bit status FIFO is sepa-
rate from the existing 3-byte receive data and error
FIFOs.
When the enhancement is enabled, the status in Read
Register 1 (RR1) and byte count for the SDLC frame will
be stored in the 10
×
19 bit status FIFO. This allows
the DMA controller to transfer the next frame into
memory while the CPU verifies that the message was
properly received.
Summarizing the operation, data is received, assem-
bled, and loaded into the 3-byte receive FIFO before be-
ing transferred to memory by the DMA controller. When
a flag is received at the end of an SDLC frame, the frame
byte count from the 14-bit counter and 5 status bits are
loaded into the status FIFO for verification by the CPU.
The CRC checker is automatically reset in preparation
for the next frame, which can begin immediately. Since
the byte count and status are saved for each frame, the
message integrity can be verified at a later time. Status
information for up to 10 frames can be stored before a
status FIFO overrun could occur.
If receive interrupts are enabled while the 10
×
19 FIFO
is enabled, an SDLC end-of-frame special condition will
6-Bit MUX
Residue Bits(3)
Overrun
CRC Error
10
×
19 Bit FIFO Array
14 Bits
6 Bits
Tail Pointer
4-Bit
Counter
14-Bit Byte Counter
Head Pointer
4-Bit Counter
5 Bits
6 Bits
8 Bits
Bits 0–5
RR7
6 Bits
RR1
2 Bits
Bit 6
Bit 7
RR6
FIFO Enable
Reset on Flag Detect
Increment on Byte DET
Enable Count in SDLC
End-of-Frame Signal
Status Read Comp
EOF = 1
Interface to SCC
Over Equal
Byte Counter Contains 14 Bits
for a 16-kb Maximum Count
FIFO Data Available Status Bit
Status Bit Set to 1
When Reading From FIFO
FIFO Overflow Status Bit
MSB of RR(7) is Set on Status FIFO
Overflow
In SDLC mode, the following definitions apply:
All Sent bypasses MUX and equals contents of SCC Status Register.
Parity bits bypass MUX and do the same.
EOF is set to 1 whenever reading from the FIFO.
WR(15) Bit 2 Set
Enables Status FIFO
RR1
4-Bit
Comparator
SCC Status Reg
(Existing)
Figure 13. SCC Status Register Modifications
10216F-17
EN
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AM85C30-8BQA | Enhanced Serial Communications Controller |
| AM8T-1203SC | 8 watt dc-dc converters |
| AM8T-1205DC | 8 watt dc-dc converters |
| AM8T-1205SC | 8 watt dc-dc converters |
| AM8T-1212DC | 8 watt dc-dc converters |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AM85C30-8/BQA | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Communications Controller |
| AM85C30-8/BUA | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Communications Controller |
| AM85C30-8BQA | 制造商:AMD 制造商全稱:Advanced Micro Devices 功能描述:Enhanced Serial Communications Controller |
| AM85C30-8BUA | 制造商:AMD 制造商全稱:Advanced Micro Devices 功能描述:Enhanced Serial Communications Controller |
| AM85C308JC | 制造商:AMD 功能描述:* |
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