Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital logic testing
Reexamination Certificate
1999-12-30
2003-02-25
Decady, Albert (Department: 2784)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital logic testing
Reexamination Certificate
active
06526534
ABSTRACT:
FIELD OF ART
The present invention relates to a communication element, which a boundary scan element for use in a wiring check for an electronic circuit substrate is applied to, and a communication apparatus using the same.
BACKGROUND ART
A boundary scan test method is proposed as a method of checking whether or not ICs packaged in an electronic circuit substrate are properly interconnected or whether or not an internal processing is properly executed in the ICs themselves.
This boundary scan test method is the test method which is applied to the electronic circuit substrate comprising the ICs in which a boundary scan element is previously incorporated. This boundary scan test method has a feature that connection check or IC operation test for an circuit substrate having such a high density that a so-called in-circuit test method cannot be employed can be performed.
An example of the conventional boundary scan element is now outlined.
FIG. 3
is a block diagram of a logic IC
100
to be tested comprising the boundary scan element.
The IC
100
comprises input terminals
101
, output terminals
102
and an internal logic
111
, as a basic constitution. The IC
100
further comprises the boundary scan element. The boundary scan element comprises input-side boundary cells
103
, output-side boundary cells
104
, a TDI terminal
105
to which data is inputted, a TDO terminal
106
from which the data is outputted, a TMS terminal
107
to which a signal for switching operation modes is inputted, a TCK terminal
108
to which a clock signal is inputted, a TRS terminal
109
to which a reset signal is inputted and a TAP circuit
110
.
The input-side and output-side boundary cells
103
and
104
are separately provided for the respective input and output terminals
101
and
102
. All the boundary cells
103
and
104
are connected in series in chain together.
The TDI terminal
105
and the TDO terminal
106
are connected to the input-side boundary cell
103
and the output-side boundary cell
104
, respectively, of the boundary cells
103
and
104
located at both the ends.
While the TAP circuit
110
is synchronized to the clock signal from the TCK terminal
108
, the TAP circuit
110
executes the processing in accordance with the signal for switching the operation modes from the TMS terminal
107
. That is, the data is shifted to the boundary cells
103
and
104
, or the data is inputted and outputted between the boundary cells
103
and
104
and the internal logic
111
or the input or output terminals
101
or
102
. The TAP circuit
110
enters a reset state in accordance with the reset signal from the TRS terminal
109
. This TRS terminal
109
is not always needed because the reset state can be included in one of commands to switch the operation modes from the TMS terminal
107
.
In the method of testing the IC
100
comprising such a constitution, the operation test for the IC is performed, e.g., as follows: test data is inputted from a host computer to the TDI terminal
105
in a serial form, and the test data is shifted and set to each of the input-side boundary cells
103
. Then, the set test data is outputted to and processed by the internal logic
111
. Subsequently, the data from the internal logic
111
is set to the output-side boundary cells
104
, and this data is then returned from the TDO terminal
106
to the host computer in the serial form. The host computer compares the returned data with the test data which the host computer previously sent out, whereby the host computer can distinguish whether or not the internal logic
111
normally operates.
The test for the connection between the ICs is carried out, e.g., as follows: the test data is sent and set from the host computer to the output-side boundary cells
104
through the TDI terminal
105
and the input-side boundary cells
103
. This data is sent out from the output terminals
102
to another IC connected to the output terminals
102
of the IC
100
.
Then, the host computer compares the test data which another IC received with the test data which the host computer had previously sent out, whereby the host computer can distinguish whether the wiring between the ICs is connected or disconnected, or the like.
On the other hand, the inventor has focused on the usefulness of the boundary scan element not as the element only for checking the wiring connection or the like but as a communication element for controlling various terminal equipment such as a CCD camera. The inventor has therefore proposed a communication apparatus in which this boundary scan element is applied to the communication element (International Publication No. WO98/55925).
However, the conventional boundary scan element is not satisfactory in a data transfer rate as the communication element.
That is, the conventional boundary scan element has a problem as follows: in order to set the data inputted from the TDI terminal
105
to each of the boundary cells
103
or
104
, the data in each of the individual boundary cells
103
or
104
must be shifted sequentially.
This problem is similarly caused when the data set in the boundary cells
103
or
104
is outputted from the TDO terminal
106
. The data transfer rate is not sufficient, particularly in the case of a large number of boundary cells
103
and
104
.
It is therefore an object of the present invention to provide a communication element, which the boundary scan element is applied to and which can increase the data transfer rate, and a communication apparatus using the same.
DISCLOSURE OF THE INVENTION
According to the present invention, there is provided a communication element which comprises a plurality of input-side boundary cells; a plurality of output-side boundary cells corresponding to the input-side boundary cells; and a TAP circuit for controlling the input and output of data to/from the input-side and output-side boundary cells, the TAP circuit being connected to a TCK line to which a clock signal is inputted, a TMS line to which a mode signal for switching operation modes is inputted, and data input and output lines for inputting and outputting the data to/from terminal equipment which is an object of communication, wherein the input-side boundary cells are connected in parallel to the corresponding output-side boundary cells through the TAP circuit.
In this element, the boundary cells are not connected in series in chain together like the prior art, but the input-side boundary cells are connected in parallel to the corresponding output-side boundary cells through the TAP circuit.
Thus, the data stored in the input-side boundary cells can be transferred to the corresponding output-side boundary cells by one processing. Consequently, a data transfer rate can be increased.
In the communication element of the present invention, the boundary cells are not connected in series. To input or output the data between the communication element and the host computer or the like, the data is thus inputted or outputted directly to/from the boundary cells in a parallel form, not in a serial form through a TDI or TDO terminal like the prior art.
According to the present invention, there is provided a communication apparatus, which comprises a plurality of communication elements of the present invention; terminal equipment separately connected to each of the communication elements, for inputting and outputting the data to/from the communication elements through the data input and output lines; and a host computer, wherein the communication elements are connected in series manner to the host computer.
According to this means, the use of the communication element of the present invention allows increasing the data transfer rate at which the data is transferred between the communication elements and between the communication element and the host computer. Thus, the large amount of data can be processed. In the present invention, the terminal equipment means the object which the communication apparatus of the present invention communicates with. For example, a monitoring apparatus ins
Chase Shelly A
De'cady Albert
Duaxes Corporation
Kanesaka & Takeuchi
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