Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
2000-09-14
2003-11-04
Decady, Albert (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C370S252000, C370S394000, C370S486000, C375S211000
Reexamination Certificate
active
06643816
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This patent application claims for benefit of the filing date of Japanese Patent Application No. P11-264560 filed on Sep. 17, 1999, the entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transmitting apparatus having an error handling function in data transmission between a network and devices, and to an error handling method. More particularly, the invention relates to a link layer data transmitting apparatus adhering to “IEEE Standard for a High Performance Serial Bus (IEEE 1394-1995 Std., hereinafter)”.
2. Description of the Related Art
In order to realize an inexpensive and high performance digital network by connecting peripheral devices of a computer apparatus and a consumer apparatus, or peripheral apparatuses with each other, IEEE 1394-1995 Std. is standardized by IEEE (Institute of Electrical and Electronics Engineers).
A protocol defined by the IEEE 1394.a has a layered structure as shown in FIG.
1
. In this protocol, a method for exchanging functions of layers such as PHY (Physical Layer)
102
and Link (Link Layer)
101
, data and control information between the layers is defined as standard. As transmission mode, there exist an Isochronous transmission
103
for transmitting data at given intervals, and an Asynchronous transmission
104
for transmitting data at arbitrary time. A format of a packet (transmitted data) transmitted between nodes in each transmission mode is also defined.
An example of format of the packet of the Asynchronous transmission
104
is shown in FIG.
2
.
The packet
110
comprises a fixed-length header portion
114
having a destination ID
111
, a source ID
112
and a data length
113
; and a variable-length data section
116
having a data field
115
. The actual length of the data field
115
can be recognized by referring to the data length
113
of the fixed-length header portion
114
.
In order to detect an error, a header CRC (Cyclic Redundancy Check)
117
is added to the end of the header portion, and a data CRC
118
is added to the end of a data portion.
Next, an example of a link layer transmitting apparatus adhering to the IEEE 1394-1995 Std., p1394.a is shown in
FIG. 3
, and an example of operation thereof is shown in
FIG. 5. A
state of stored data in a data storingiregion
14
a
is shown in FIG.
4
.
The transmitting apparatus
10
a
comprises a lower interface
11
, a CRC judging section
12
, a reception-controlling section
13
a
, and the data storing region
14
a
and a higher interface
15
a.
When the lower interface
11
receives data through a data signal
16
(step S
30
), the lower interface
11
transmits a packet received through a data signal
17
and a data signal
18
to the CRC judging section
12
and the reception-controlling section
13
a.
The reception-controlling section
13
a
refers to the header portion
114
of the received packet
110
(step S
31
), and judges whether the received data is directed to the own node (step S
32
). If the data is directed to the own node, a reception packet is formed and stored in the data storing region
14
a
(FIFO/RAM) through a data signal
19
a
, and waits a result of CRC error judgment from the CRC judging section
12
.
The CRC judging section
12
judges whether there is a CRC error in the received packet
110
, and transmits the judgment result to the reception-controlling section
13
a
through a control signal
22
.
The reception-controlling section
13
a
generates an acknowledge signal to be returned to the source node based on the CRC judgment result, transmits the acknowledge signal
26
to the lower interface
11
, and stores the same in acknowledge information
120
(AckSent) of the data storing region
14
a
. Further, the reception-controlling section
13
a
informs the higher interface
15
a
that the reception was completed, and the higher interface
15
a
informs higher application
45
(step S
33
, step S
35
).
The header portion
114
and the data portion
116
of the received packet
110
are sequentially stored in the data storing region
14
a
. A speed information
119
(Spd) of the corresponding packet
110
and an acknowledge signal sent back to the source with respect to the corresponding received packet are added to the end of the data portion as the acknowledge information
120
(AckSent). The header CRC
117
and a data CRC
118
of the received packet
110
are eliminated. A plurality of received packets
110
can be stored in the data storing region
14
a.
The acknowledge signal
26
to be sent back to the source and the acknowledge information
120
to be stored in the data region are defined as follows: “complete”: reception completion (no responding packet exists), “pending”: reception completion (responding packet exists), “busy”: own node is busy and packet could not be received, “data error”: there was error in the received packet.
When the higher application
40
is informed by the transmitting apparatus
10
a
that a packet has been received, the higher application
40
reads out data from the data storing region
14
a
through the higher interface
15
a
(step S
36
). At that time, the acknowledge information
120
can be referred based on the data length
113
stored in the data storing region
14
a
, and it is possible to judge whether there is an error in the received packet (steps S
36
to S
36
b
).
However, the above-described transmitting apparatus has the following problems.
Firstly, since the acknowledge information is located behind the data portion, even if the CRC error is detected in the received packet in the transmitting apparatus, the higher application can not recognize that the CRC error is occurred until all the data in the packet is read in. Therefore, it is necessary to read in all the data including unnecessary error data, and especially when a packet having large data length is processed, the processing time of the higher application is largely increased.
Secondly, even when a normal packet having no error was received and the higher application was informed that the reception of the packet had been completed, the higher application can not utilize the packet. until the application read all the data in the packet and confirms the acknowledge information. For example, when the application desires to utilize only the top of the data portion, the higher application must read in all the data including the unnecessary portion.
Thirdly, when an error is occurred in the reception packet and data length in the header portion of the packet and the actual data length are different, it is impossible to recognize where of the data storing region the acknowledge information is stored. Therefore, there is an adverse possibility that the higher application can not precisely judges whether there is an error in the received packet of the application erroneously judges.
Fourthly, like the third problem, when data length in the header portion of the packet and the actual data length are different, if the next packet is received and stored in the data storing region in the state in which the packet having the error remains in the state storing region, a data storing-starting position of this packet data can not be recognized.
SUMMARY OF THE INVENTION
The present invention has been accomplished to solve the above-described conventional problems, and it is an object of the invention is to provide a transmission apparatus having an error handling function and an error handling method capable of recognizing whether a data CRC error is occurred without reading out all the received data, and in which no malfunction occurs even when data length in the header portion of the packet and the actual data length are different.
To achieve the above object, a first aspect of the present invention is characterized in that when an error was detected in a received packet, a higher application is informed that the error was occurred, and when no error was detected in the received packet, a higher app
Inoue Noriko
Uesugi Kouki
De'cady Albert
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Whittington Anthony T.
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