PT7A6632 Datasheet, PDF (24/61 Pages) Pericom Semiconductor Corporation – PT7A6632 32-Channel HDLC Controller

Data Sheet
PT7A6632 32-Channel HDLC Controller
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Data Processing Memory
General
There are 4 kinds of buffers, Transmit Data Buffer and Trans-
mit Command Buffer for transmit channels, and Receive Data
Buffer and Receive Command Buffer for receive channels.
The Data Processing Memory refers to Data or Command buff-
ers which are linked each other. The PT7A6632 accesses the
Data Processing Memory for transmit/receive data and opera-
tion commands. Each buffer has following configuration (see
Figure 22):
• 8-Byte Descriptors
• Data bytes to be transmitted or received or Command
Transmit Data Buffer
The Transmit Data Buffer contains 8 bytes of descriptors and j
bytes of user’s data as shown in Figure 23. The MDFS pin
decides the most significant byte and least significant byte
locations (in even and odd addresses).
Figure 23. Transmit Data Buffer
(Address) 7
(Contents)
0
i msb
i+1
Next Buffer
lsb ^Address
i+2
Not used
msb
i+3
Buffer
lsb ^{Size (k)}
i+4
FC FO _{Not used msb}
i+5
Data
lsb ^{Length (j)}
i+6
Not Used by PT7A6632
i+7
UNDR IVBA
Not used
- _CF/P
CMND MPTY
(0)
Status
(i+7)+1
First Date Byte
(i+7)+2
Second Date Byte
~~
~~
(i+7)+j
(i+7)+j+1
Last Date Byte
Flag Count (Optional)
~~
~~
(i+7)+k
Last Location in Buffer
a. MDFS = 1
(Address) 7
(Contents)
0
i
i+1 _msb
lsb _{Next Buffer}
Address
i+2
i+3
Not used
msb
lsb _Buffer
Size (k)
i+4
lsb _Data
i+5
i+6
- ^{FC FO Not used msb}
Length (j)
UNDR IVBA
Not used
CF/P
CMND
(0)
MPTY
Status
i+7
Not Used by PT7A6632
(i+7)+1
(i+7)+2
First Date Byte
Second Date Byte
~~
~~
(i+7)+j
(i+7)+j+1
Last Date Byte
Flag Count (Optional)
~~
~~
(i+7)+k
Last Location in Buffer
b. MDFS = 0
• Descriptors
The first 8 bytes in the transmit Data Buffer is Descriptors that
specifies Next Buffer Address, Buffer Size, Data Length and
Status respectively. See Table 6 for the definition.
• Data Bytes
Following the Descriptors are the data to be transmitted. The
number of bytes are specified by Data Length (for complete
data buffer) or Buffer Size (for partial data buffer). The buffer
may contains last byte of a frame (CF/P = 1) or partial data of a
frame (CF/P = 0) in HDLC mode. The CF/P should be reset for
other modes.
• Flag Count Byte (Optional)
Specifies the additional flags to be added after “CRC + one
Flag” of a frame. It will be read only when Flag Control bit in
the MS byte of Data Length is set (FC = 1).
PT019(05/02)
24
Ver:2