WO2005031379A1

WO2005031379A1 - System and method for generating reference signals, test equipment and method using such reference signals

Info

Publication number: WO2005031379A1
Application number: PCT/IB2004/003051
Authority: WO
Inventors: Patrice Gibon
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2003-09-24
Filing date: 2004-09-14
Publication date: 2005-04-07

Abstract

The invention relates to a method and system for generating reference signals intended to characterize the functioning of a component to be tested, said method comprising : a step of sending, from a control system (101), control signals to a reference component (102) of the same type as the component to be tested, a recording step of recording the signals exchanged between the control system (101) and the reference component (102), the said exchanged signals constituting said reference signals. Use: Generation of test signals/Testing of components

Description

System and method for generating reference signals, test equipment and method using such reference signals

FIELD OF THE INVENTION The invention relates to a system and method for generating reference signals intended to characterize the functioning of a component to be tested. The invention also relates to test equipment and a test method using such reference signals for testing the functioning of a component. The invention has in particular applications for testing the functioning of electronic cards and integrated circuits when coming off production lines.

BACKGROUND OF THE INVENTION Electronic components, in particular electronic cards and integrated circuits, are normally tested after they come off the production lines. To perform the tests, previously defined test signals (also referred to as "test vectors", "test patterns" or "stimuli") are applied directly by test equipment to the inputs of the electronic card or integrated circuit, which thus generates a specific response characterizing its functioning. This specific response is then compared with a model response in order to determine whether or not the functioning of the electronic card or integrated circuit is correct. In order to define the test signals and the ideal response of the component to be tested, a global simulation of the circuit at the level of the silicon must be performed. This simulation may therefore prove to be very lengthy, in particular in the case of mixed components composed of several analog and digital functional units, which makes it expensive. In addition, this simulation requires perfect knowledge of the architecture of the component to be tested, which limits the use of these tests to highly skilled persons. This approach is made all the more expensive because the integration density of integrated circuits is constantly increasing, which involves the number of test signals which must be determined and applied also increasing very greatly in order to guarantee an exhaustive and reliable test. In addition, these test signals are normally stored in memories with high storage capacities at the test equipment, which involves a not insignificant additional cost. Finally, this approach does not allow to test components of the signal processor type using for their functioning codes of instructions stored in an external memory since the computer simulation of such architectures is very complex. The ideal response of these components can therefore not be simulated.

SUMMARY OF THE INVENTION The invention aims at proposing a method for generating reference signals intended to characterize the functioning of a component to be tested, said method being reliable, inexpensive and rapid in its implementation.

For this purpose, the method for generating reference signals according to the invention comprises : - a step of sending, from a control system, control signals to a reference component of the same type as the component to be tested, - a recording step of recording the signals exchanged between the control system and the reference component, the said exchanged signals constituting said reference signals. Contrary to the prior art, where the reference signals characterizing the ideal response of the component to be tested, in response to control signals, are generated via a computer simulation of the component, the reference signals generated by the method according to the invention issue from the recording of the input/output signals exchanged between the control system and the reference component. The purpose of the reference signals is to be compared with the responses of the components to be tested when the same control signals are applied to them, the components to be tested being of the same type as the reference component used for defining the reference signals. In this way, the reference signals are defined when the reference component is used in an application environment, the control signal making it possible to reproduce, via the sending of the control signals, the application environment for which the component is intended. The functioning of the reference component is deemed to be correct at least in this application environment. The signals exchanged comprise the control signals generated by the control system and the signals generated by the reference component in response to these control signals. By recording the signals exchanged between the control system and the reference component, this method makes it possible to generate reference signals rapidly without having to know the internal architecture of the component, and therefore without having to simulate its behavior by means of complex computer means. The application environment in which the reference component is used can advantageously be modified in order to know and record the ideal responses of the reference component in this particular environment, for example by associating with the reference component other elements such as a memory containing codes of instructions. It is therefore possible to target the type of reference signal according to the application environment for which the component to be tested in the end is intended.

Another aim of the invention is to propose a system for generating reference signals intended to characterize the functioning of a component to be tested, said system comprising means for implementing the various steps of the method according to the invention.

Another aim of the invention is to propose a test method for testing the functioning of a component, said test method comprising: - a step of sending, from a control system, control signals to a reference component of the same type as the component to be tested, - a recording step of recording the signals exchanged between the control system and the reference component, said exchanged signals constituting reference signals, - a step of sending, from a control system, said control signals to the component to be tested, - a recording step of recording the signals exchanged between the control system and the component to be tested, - a comparison step of comparing said reference signals with said signals exchanged between the control system and the component to be tested.

The signals exchanged between the control system and the component to be tested are recorded and then compared with the reference signals previously defined by the method according to the invention. If the signals exchanged between the control system and the component to be tested are identical to the reference signals, the component to be tested is considered to have correct functioning. If the signals exchanged between the control system and the component to be tested are not identical to the reference signals, the component is considered to have faulty functioning.

Detailed explanations and other aspects of the invention will be given below.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further described with reference to examples of embodiments shown in the drawings to which, however, the invention is not restricted. Fig.l describes the outline diagram of the invention, Fig.2 describes test equipment according to the invention, Fig.3 describes the various steps of a test method according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Fig.l describes the outline diagram of the invention for generating reference signals characterizing the ideal response of a component to be tested, the reference signals being used subsequently for testing the validity of functioning of a component of the same type. The reference signals generated by the method according to the invention issue from the recording of the signals exchanged between the control system 101 and a reference component 102. The purpose of the reference signals is to be compared with the signals exchanged between a control system and the components to be tested when they are subjected to the same control signals as those applied to the reference component 102, the components to be tested being of the same type as the reference component used for defining the reference signals. The reference component 102 is for example an electronic card or an integrated circuit which has undergone many experimental tests attesting to its correct functioning. The signals exchanged between the control system 101 and the reference component 102, resulting from the sending of control signals by the control system 101 to the reference component 102, are recorded by the recorder 103. The method according to the invention comprises: - a step of sending, from the control system 101, control signals to the reference component 102 of the same type as the component to be tested, - a recording step of recording the signals exchanged between the control system 101 and the reference component 102, said exchanged signals constituting said reference signals. The signals exchanged between the control system 101 and the reference component 102 characterize the ideal functioning of the component, at least with regard to the control signals sent by the control system 101.

The method according to the invention for generating reference signals can be implemented in the form of a system described in Fig.2, this system comprising: - a support 204 intended to receive the reference component 202 of the same type as the component to be tested. This support is advantageously provided with an interface circuit 206 enabling the reference component 202 to communicate with a control system 201, for example via the data bus 205. - a control system 201 connected to the support 204 in order to send control signals to the reference component 202. This control system advantageously corresponds to computer equipment of the PC type (from the English "Personal Computer") provided with interface circuits (not shown) for dialoguing with the reference component 202 via the data bus 205. - a recorder 203 for recording the signals exchanged between the control system 201 and the reference component 202, said exchanged signals constituting said reference signals. The recorder 203 makes it possible to record on the data bus 205 not only the control signals (the "incoming" signals) sent by the control system 201, but also the output signals (the "outgoing" signals) generated by the reference component 202 in response to the "incoming" signals. Such a recorder corresponds to a bus analyzer or to a logic analyzer known to persons skilled in the art. The recorder is connected either to the data bus 205 as shown, or directly to one or more output terminals of the reference component 202. Advantageously, the exchanged signals which are recorded on the data bus 205 are preferably shaped by the recorder 203 according to a standard format by means of a suitable processing step so that the corresponding data file can be read easily by standard test equipment, for example of the Teradyne type. A standard format of this type will be illustrated below by Table 1. In the case where the recorder does not deliver the signals directly to the format of a tester (for example Teradyne or other, well known by skilled persons), a conversion strip may be added and executed independently on a computer, for example by means of a script.

A set of control signals is applied to the reference component 202, this set of control signals not being exhaustive but limited to the principal functions fulfilled by the reference component 202 in the application environment for which it is intended. For example, the control signals sent by the control system 201 to the reference component 202 correspond to: - a so-called enumeration command intended for the mutual recognition of the reference component 202 with the control system 201, the characteristics of this control signal being known per se to persons skilled in the art. - a command for reading/writing in an external system corresponding for example to a chip card 207 (the chip card performing a communication 208, by cable or wireless, via the interface 209 with the reference component 202), or to an audio/video data processing apparatus 212 connected to the data bus 205. For this purpose, the reference component must be in a position to generate an output signal on the data bus 205 indicating to the control system 201 that the command for reading/writing with the external system has taken place correctly. - a command for reading/writing in a memory 210. For this purpose, the reference component must be in a position to generate an output signal on the data bus 205 indicating that the command for reading/writing in the memory 210 has taken place correctly. - a command instruction to the microprocessor 211, the latter sending in response to this command instruction secondary control signals to the reference component 202.

Table 1 shown in the following pages contains non-limitingly a list of numerical values corresponding to signals exchanged between the control system 201 and the reference component 202. These signals issue from a recording on the data bus 205 in accordance with the USB standard (from the English "Universal Serial Bus"), possibly preceded by shaping in a format intended to be used in a tester of the Teradyne type, the shaping being for example formed by means of a script. The reference signals correspond to the columns called DPOS, DNEG, RESET and XTAL1. The signals DPOS and DNEG correspond to the input/output signals on the data bus 205, the signal RESET is a signal for the resetting to zero of the reference component 202 by the control system 201, whilst the signal XTAL1 is an additional signal intended to be applied directly to a particular input of the reference component 202 in order to modify its functioning configuration. The signal XTAL1 is used in the case where said particular input is not accessible via the data bus 205. A state "0" corresponds to a logic 0 state, a state "1" corresponds to a logic 1 state, a state "H" corresponds to a logic high state, a state "L" corresponds to a logic low state, a state "X" corresponds to an indifferent logic state. The number of the clock pulses is identified by the values contained in the vector column. The signals having a "1" or "0" state correspond to the control signals sent by the control system 201 to the reference component 202 via the data bus 205. The signals having a state "H" or "L" correspond to the output signals of the reference component 202. For example, on the clock pulse number 513, the control signal "1 0 0 1" is sent over the data bus 205 by the control system 201. In response to this control signal, on the clock pulse number 514, the reference component 202 generates the output signal "L H 0 1". This output signal therefore characterizes the ideal functioning of the reference component

202 when the control signal "1 0 0 1" on the clock pulse 513 is applied to it.

0000503 - 1 0 0 1 0000504 - 0 1 0 1 0000505 - 1 0 0 1 000050G - 1 0 0 1 0000507 — 0 1 0 1 0000503 0 1 0 1 0000509 - 0 1 0 1 0000510 - 0 1 0 1 0000511 - 0 1 0 1 0000512 REPEAT 3 - 0 0 0 1 /* End Of DATAO */ 0000513 REPEAT 5 - 1 0 0 1 /* IDLE */ 0000514 - L H 0 1 ACK packet */ 0000515 - H L 0 1 0000516 - L H 0 1 0000517 - H L 0 1 0000513 L H 0 1 0000519 H L 0 1 0000520 - L H 0 1 0000521 — L H 0 1 0000522 - H L 0 1 0000523 H L 0 1 0000524 : L H 0 1 0000525 - H L 0 1 0000526 - H L 0 1

Table 1: Example of reference signals recorded on the data bus 205 Fig.3 describes the various steps of a test method according to the invention for testing the functioning of a component, said test method comprising: - a step 301 for sending, from a control system, control signals to a reference component of the same type as the component to be tested. This test 301 corresponds to the step described above for sending control signals to the reference component 202. - a recording step 303 for recording the signals exchanged between the control system and the reference component, said exchanged signals constituting reference signals. This step 303 corresponds to the step described above for recording the signals exchanged between the control system 201 and the reference component 202. This recording step 303 is if necessary followed by a shaping step 302 (i.e. format conversion) in order to shape the signals recorded so that they can be used easily in standard test equipment, for example of the Teradyne type. - a step 304 for sending, from a control system, said control signals to the component to be tested. - a recording step 305 for recording the signals exchanged between the control system and the component to be tested. This recording step 303 is if necessary followed by a shaping step 306 in order to shape the signals recorded so that they can be used easily in standard test equipment, for example of the Teradyne type. - a comparison step 307 for comparing said reference signals with said signals exchanged between the control system and the component to be tested. This comparison is repeated for each clock pulse.

The test method according to the invention can be implemented in the form of test equipment for testing the functioning of a component, said test equipment comprising: - a first support intended to receive a reference component of the same type as the component to be tested, - a control system connected to the first support for sending control signals to the reference component. This control system corresponds for example to computer equipment of the PC type. - a recorder for recording the signals exchanged between the control system and the reference component, said exchanged signals constituting reference signals. The recorder corresponds to a bus analyzer or to a logic signal analyzer. - a second support intended to receive the component to be tested, - a control system connected to the second support for sending said control signals to the component to be tested. This control system corresponds for example to a tester of the Teradyne type. - a recorder for recording the signals exchanged between the control system and the component to be tested. The recorder corresponds to a bus analyzer or to a logic signal analyzer. - comparison means for comparing said reference signals with said signals exchanged between the control system and the component to be tested. The comparison means are advantageously included in the tester, and are for example used by a signal processor executing codes of instructions stored in a memory. The reference signals are also stored in memory in the tester.

If the signals exchanged between the control system and the component to be tested are identical to the reference signals, the component to be tested is considered to have correct functioning. If the signals exchanged between the control system and the component to be tested are not identical to the reference signals, the component is considered to have faulty functioning.

Advantageously, one and the same component support can be used, the reference component being replaced by the component to be tested before performing step 304. Likewise, a single recorder can be used for recording the signals exchanged between the control system and the reference component, and for recording the signals exchanged between the control system (that is to say the tester) and the component to be tested. In this case, such an item of test equipment is illustrated by Fig.2.

For example, referring to Table 1, when a component to be tested of the same type as the reference component 201 is inserted in place of the reference component 202, the same control signal "1 0 0 1" is sent over the data bus 205 on clock pulse number 513. On the following clock pulse number 514, the comparison step 307 compares the signal recorded on the data bus with the reference signal "L H O 1". This comparison is repeated for each clock pulse. If the signal recorded is identical to the reference signal "L H O 1", the component to be tested is considered to have correct functioning in response to this control signal. If the signal recorded is not identical to the reference signal "L H O 1", the component is considered to have defective functioning. The component to be tested is considered to have correct overall functioning if, on each successive clock pulse, the signal recorded is identical to the reference signal.

The invention has been illustrated with reference to a data bus of the USB type for connecting the control system to the reference component or to the component to be tested. However, other types of data bus can be used, for example a bus of the I²C type, a serial bus of the RS232 type or a parallel bus of the SPI type.

Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in the claims. Use of the article "a" or "an" preceding an element or step does not exclude the presence of a plurality of such elements or steps.

Claims

1. A method for generating reference signals intended to characterize the functioning of a component to be tested, said method comprising: - a step of sending, from a control system (101), control signals to a reference component (102) of the same type as the component to be tested, - a recording step of recording the signals exchanged between the control system (101) and the reference component (102), the said exchanged signals constituting said reference signals.

2. A method as claimed in Claim 1, comprising an additional format conversion step of converting the format of said exchanged signals.

3. A system for generating reference signals intended to characterize the functioning of a component to be tested, said system comprising: - a support (204) intended to receive a reference component (202) of the same type as the component to be tested, - a control system (201) connected to the support (204) in order to send control signals to the reference component (202), - a recorder (203) for recording the signals exchanged between the control system (201) and the reference component (202), said exchanged signals constituting said reference signals.

4. A system as claimed in Claim 3, wherein the control system (201) and the reference component (202) are connected by a data bus (205) via the support (204), the recorder (203) being coimected to the data bus (205) in order to record said exchanged signals.

5. A system as claimed in Claim 3, wherein the recorder (203) is connected to one or more output terminals of the reference component (202) in order to record said exchanged signals.

6. A system as claimed in Claim 3, 4 or 5, comprising additional processing means for converting the format of said exchanged signals.

7. A method of testing the functioning of a component, said method comprising: - a step (301) for sending, from a control system, control signals to a reference component of the same type as the component to be tested, - a recording step (303) for recording the signals exchanged between the control system and the reference component, said exchanged signals constituting reference signals, - a step (304) for sending, from a control system, said control signals to the component to be tested, - a recording step (305) for recording the signals exchanged between the control system and the component to be tested, - a comparison step (307) for comparing said reference signals with said signals exchanged between the control system and the component to be tested.

8. Equipment for testing the functioning of a component, said test equipment comprising: - a first support intended to receive a reference component of the same type as the component to be tested, - a control system connected to the first support for sending control signals to the reference component, - a recorder for recording the signals exchanged between the control system and the reference component, said exchanged signals constituting reference signals, - a second support intended to receive the component to be tested, - a control system connected to the second support for sending said control signals to the component to be tested, - a recorder for recording the signals exchanged between the control system and the component to be tested, - comparison means for comparing said reference signals with said signals exchanged between the control system and the component to be tested.