JP3069717B2 - Test method for communication IC - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for testing a communication IC having an asynchronous / synchronous conversion function.

[0002]

2. Description of the Related Art A communication interface having an asynchronous / synchronous conversion function
When testing the operation of C, it is necessary to perform the test in consideration of the fluctuation of the communication speed of the asynchronous character signal with respect to the communication speed of the clock signal.

[0003]

Therefore, it has been difficult to perform a test with a simple hardware configuration and a test with high reliability.

An object of the present invention is to provide a method for testing a communication IC that receives an asynchronous character signal and a clock signal from a modem and outputs a synchronous character signal, and performs a high reliability test with a simple hardware configuration. It is to provide a possible test method.

[0005]

SUMMARY OF THE INVENTION A communication I according to the present invention is provided.
The test method C is a process of simulating the operation of the communication IC to form a first asynchronous character signal, a first clock signal and a first synchronous character signal, and sampling each of the above signals at a predetermined period. Forming a first asynchronous character signal sampling signal, a first clock signal sampling signal, and a first synchronous character signal sampling signal; and forming a second asynchronous character signal and a second clock signal based on the sampling signals. , The second asynchronous character signal and the second
Inputting a clock signal to the communication IC to output a second synchronization character signal from the communication IC, and sampling the second synchronization character signal at a predetermined period to form a second synchronization character signal sampling signal When,
Comparing the first synchronization character signal sampling signal with the second synchronization character signal sampling signal.

[0006]

FIG. 1 is a time chart showing a test method for a communication IC having an asynchronous / synchronous conversion function. FIG. 2 is a diagram showing a configuration in a case where the operation of the communication IC is tested using the method of FIG. The communication IC 11 inputs an asynchronous character signal and a clock signal from a modem and outputs a synchronous character signal. The synchronous tester 12 tests the operation of the communication IC 11.

Hereinafter, this test method will be described with reference to FIGS. 1 and 2.

In the first step, the operation of the communication IC 11 is logically simulated and the asynchronous character signal A1 (first
An asynchronous character signal), a clock signal B1 (first clock signal) and a synchronous character signal C1 (first synchronous character signal) are formed. STA is a start bit, STP is a stop bit, and 1 to N are data bits. Normally, the cycle Tx of one bit of the asynchronous character signal A1 and the cycle T of one clock of the clock signal B1 are used.
s (eg, Tx = 0.975 × T
s and Tx = 1.01 to 1.023 × Ts.

In the second step, the asynchronous character signal A1, clock signal B1 and synchronous character signal C1
, A sampling signal A2 (first asynchronous character signal sampling signal), a sampling signal B2 (first clock signal sampling signal), and a sampling signal C2 (first synchronous character A signal sampling signal) is formed. The sampling cycle is the above cycle T
It is much shorter than s and Tx.

In the third step, the sampling signal A2
By sequentially connecting each bit of each sample value sequence of the sampling signal B2 at the same period as the sampling period, the asynchronous character signal A3 substantially the same as the asynchronous character signal A1 and the clock signal B1 is connected.
(Second asynchronous character signal) and clock signal B3
(Second clock signal) is formed. That is, the asynchronous character signal A3 and the clock signal B3 are sampled once from the asynchronous character signal A1 and the clock signal B1, and then re-synthesized using a bit pattern having the same cycle as the sampling cycle. .

In the fourth step, the asynchronous character signal A3
And the clock signal B3 is transmitted from the synchronous tester 12 to the communication IC 11. If the communication IC 11 is normal,
The communication IC 11 outputs a synchronization character signal C3 (second synchronization character signal) substantially the same as the synchronization character signal C1.

In the fifth step, the synchronous character signal C3 is sampled by the synchronous tester 12, and the sampling signal C4 is sampled by each sample value sequence obtained at that time.
(Second synchronous character signal sampling signal) is formed. The sampling period at this time is equal to the sampling period in the second process.

In the sixth step, the sampling signal C2
And the sampling signal C4 are compared by a comparator in the synchronous testing machine 12. That is, the sampling signal C
2 is compared with the sample value series of the sampling signal C4. If the two are equal, the communication IC 11 is determined to be good, and if they are not equal, it is determined to be defective.

As described above, according to the test method, each simulated signal has a sampling period sufficiently shorter than the period Tx of one bit of the asynchronous character signal A1 and the period Ts of one clock of the clock signal B1. Is sampled, and a test of the communication IC 11 is performed using each sample value sequence obtained at that time. Therefore, when testing the communication IC 11 by variously changing the difference between the cycle Tx of one bit of the asynchronous character signal A1 and the cycle Ts of one clock of the clock signal B1, a signal with high accuracy can be easily obtained. Can be formed.

[0015]

According to the present invention, since a signal for testing a communication IC having an asynchronous / synchronous conversion function can be easily formed with high accuracy, a highly reliable test can be performed with a simple hardware configuration. Can be performed.

[Brief description of the drawings]

FIG. 1 is a time chart showing a test method of a communication IC having an asynchronous / synchronous conversion function.

FIG. 2 is a block diagram showing a configuration for testing the operation of a communication IC using the method of FIG. 1;

[Explanation of symbols]

 A1 first asynchronous character signal B1 first clock signal C1 first synchronous character signal A2 first asynchronous character signal sampling signal B2 first clock signal sampling signal C2 first synchronous character signal Sampling signal A3 Second asynchronous character signal B3 Second clock signal C3 Second synchronous character signal C4 Second synchronous character signal sampling signal

Claims (1)

(57) [Claims] 1. A method for testing a communication IC which receives an asynchronous character signal and a clock signal from a modem and outputs a synchronous character signal, comprising the steps of: simulating the operation of the communication IC; A corresponding first asynchronous character signal,
Forming a first clock signal corresponding to the clock signal and a first synchronous character signal corresponding to the synchronous character signal; and determining the first asynchronous character signal, the first clock signal, and the first synchronous character signal in a predetermined manner. Forming a first asynchronous character signal sampling signal, a first clock signal sampling signal, and a first synchronous character signal sampling signal, and sampling the first asynchronous character signal sampling signal and the first clock signal sampling cycle. Forming a second asynchronous character signal substantially the same as the first asynchronous character signal and a second clock signal substantially the same as the first clock signal based on the signal; Clock signal for the above communication C, outputting a second synchronizing character signal substantially the same as the first synchronizing character signal from the communication IC, sampling the second synchronizing character signal at a predetermined period, A method for testing a communication IC, comprising: forming a character signal sampling signal; and comparing the first synchronization character signal sampling signal with the second synchronization character signal sampling signal.