JPH0554632B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit for detecting misconnection and open conditions in a multi-conductor electrical connector. More specifically, it relates to a circuit that detects incorrect connection when a multicore cable is connected to a microprocessor connector in a device using a microprocessor that has at least two power supply terminals with the same voltage. .

[Prior Art] With the remarkable development of semiconductor technology, the functions of microprocessors have continued to expand, and the number of pins of the microprocessors has also increased.

For this reason, the need for debugging both hardware and software has increased, and opportunities to connect multicore cables to microprocessor connectors using multicore connectors have increased.

For example, by analyzing the operation of a microprocessor using an emulator or logic analyzer,
When checking, such a measuring device is connected to a microprocessor connector using a multicore connector with a multicore cable.

[Problems to be Solved by the Invention] However, when connecting the connector from such a measuring instrument to the connector of a microprocessor, it may happen that the connector is connected in the opposite direction to the correct connector connection direction, or There is an increasing chance that the connector pins will be connected out of alignment with the correct pin positions.

Conventionally, no countermeasures have been taken against such misconnections, and as a result, the problem is that they can damage the device under test on which the microprocessor is mounted, or even damage the measuring instrument itself. It was hot.

[Means for Solving the Problems] The present invention has been made in order to solve the above problems, and provides a method for connecting to a microprocessor connector having at least two power supply terminals of the same voltage. This provides a measurement connector circuit.

In other words, a resistor is connected to the ground between the first and second pins of the measurement connector that are connected to the two power supply pins, and the first pin is connected to the power supply of the measuring instrument through the resistor. The first pin is connected to two comparators for comparing two different voltages, the output of which is connected to alarm means.

[Function] When the measurement connector is correctly connected to the microprocessor connector and the device under test is still powered off, the first and second pins are shorted through the microprocessor connector. , indicating low voltage.

Then, when the power to the device under test is turned on, the first
The pin is supplied with power from the device under test and becomes a high voltage.

If an incorrect or incomplete connection is made, the first pin will not be connected to the power supply of the device under test and will not be shorted to the second pin, resulting in an intermediate voltage. The respective voltages appearing on the first pin in such a case are compared by two comparators, and if the voltage is not normal, an alarm means is operated to issue an alarm.

[Example] An embodiment of the present invention is shown in FIG. 1 and will be described.

In FIG. 1, 10 is the connector jack of the microprocessor of the device under test, 11 and 1
2 are pins of the jack 10, and both pins are short-circuited and connected to the power supply V _A of the device under test.
20 is a plug of a measuring connector for connecting a measuring instrument to the jack 10; 21 is the first plug of the plug 20;
Pin 22 is the second pin of plug 20 and fits into pins 11 and 12, respectively. 25, 26, 27
is a resistor, and the resistor 25 connects one end to the power supply of the measuring instrument.
The other end of V _C is connected to the first pin 21, and the resistor 26
is connected between the second pin 22 and ground, and the resistor 27 is connected between the first pin and ground. 30 and 36 are a first comparator and a second comparator, respectively, one input terminal of each comparator is both connected to the first pin 21, and the other input terminal is connected to the first reference voltage 31 (voltage
V _D ) and a second reference voltage 37 (voltage V _E ). 32 and 38 are the fourth output terminal of the first comparator 30 and the second output terminal of the second comparator 36, respectively. 41 is an inverter, 42 is a NAND gate, 43 is a buzzer connected between the NAND gate and the power supply V _C ,
41, 42, and 43 constitute alarm means.

Next, the operation of the circuit shown in FIG. 1 will be explained.

The jack 10 and the plug 20 are properly fitted, the power supplies V _A and V _C are, for example, 5 V, the voltage V _D of the first reference voltage 31 is, for example, 4.5 V, and the voltage V _E of the second reference voltage 37 is, for example, 1.5 V. V, resistor 25 is, for example, 1KΩ, resistor 26 is, for example, 100Ω, resistor 2
7 is set to 1KΩ, for example.

If the non-measuring device is not powered on yet, the power supply V _C at one terminal of the first comparator 30 and the second comparator 36 is divided by the resistor 25 and the resistors 26 and 27 connected in parallel. Therefore, the value is sufficiently smaller than the second reference voltage V _E (1.5 V), and V _B < V _D and V _B < V _E , so that the voltage at the first output terminal 32 of the first comparator 30 and , the voltages at the second output terminal 38 of the second comparator 36 both become a low voltage "L" level, as shown in state S1 in FIG.

Next, when the device under test is powered on, the voltage
Since V _B is equal to the power supply V _A (5V) of the device under test, V _B > V _D and V _B > V _E , and the outputs of both the first comparator 30 and the second comparator 36 are "H". Therefore, the voltages at the first output terminal 32 and the second output terminal 38 become as shown in state S2 in FIG. 2.

Next, when the plug 20 is removed from the jack 10, the voltage V _B becomes the value obtained by dividing the voltage V _C by the resistors 25 and 27 (2.5V), so V _B <
V _D , V _B > V _E , the output of the first comparator 30 becomes "L" level, the output of the second comparator 36 becomes "H" level, and the voltages at the first output terminal 32 and the second output terminal 38 is as shown in state S3 in FIG.

If the plug 20 is connected to the jack 10 out of position, the same state as shown in state S3 will occur.

Therefore, in a normal state, the voltages at the first output terminal and the second output terminal are both at "L" level (state S1), or both are at "H" level.
level (state S2). In addition, in an abnormal state, the voltage of the first output terminal 32 is at "L" level,
The voltage at the second output terminal 38 is at “H” level (state S
3).

Therefore, alarm means consisting of an inverter 41, a NAND gate 42, and a buzzer 43 is connected to the first output terminal 32 and the second output terminal 38 to alarm this abnormal state. That is, the voltage at the first output terminal 32 is inverted by the inverter 41 and applied to one input terminal of the NAND gate 42,
The voltage at the second output terminal 38 is directly input to the other input terminal of the NAND gate 42.

Therefore, in state S1, one terminal of the NAND gate 42 is at "H" level and the other terminal is at "L" level, and since there is no output from the NAND gate, a voltage is applied to the buzzer 43. It doesn't join, it doesn't ring. In state S2, one terminal of the NAND gate 42 is at the "L" level and the other terminal is at the "H" level, and since there is no output from the NAND gate, no voltage is applied to the buzzer 43. will not ring. In state S3, both terminals of the NAND gate 42 go to "H" level, voltage is applied to the buzzer 43, and the buzzer sounds.

Here, an AND gate may be used in place of the NAND gate 42, and a buzzer may be connected between the output of the AND gate and the ground.

A light emitting element such as a light emitting diode may be used in place of the buzzer 43, which is an alarm element that issues an alarm. Instead of the above-mentioned alarm means 41, 42, 43,
An alarm may be displayed on the display section of the measuring instrument.

[Effects of the Invention] As is clear from the above explanation, if the measurement connector is not correctly connected to the connector of the microprocessor of the device under test, an alarm will be issued. In today's world, as the functionality of microprocessors expands, opportunities for debugging increase, and the number of pins on microprocessor connectors increases, which increases the possibility of incorrect connections. The effects of the present invention are extremely large.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
This figure is a diagram for explaining the state of the circuit shown in FIG. 1. 10... Jack, 11, 12... Pin, 20
...Plug, 21...First pin, 22...Second pin, 25-27...Resistor, 30...First comparator, 31...First reference voltage, 32...First output terminal, 36... ...Second comparator, 37...Second
Reference voltage, 38...Second output terminal, 41...Inverter, 42...NAND gate, 43...Buzzer.

Claims (1)

[Claims] 1. A first pin and a second pin that are connected to the two pins for fitting into a connector of a microprocessor of a device under test, in which at least two of the plurality of pins have the same voltage. a first resistor connected between a first pin of the connecting means and a power supply of a measuring instrument having a voltage close to that of the power supply of the device under test; and a connection between the first pin and ground. a second resistor having a resistance value close to that of the first resistor, which is connected between the second pin and the ground; a third resistor having one terminal connected to the first pin and the other terminal having a voltage lower than the power supply of the measuring device;
a first comparing means connected to a reference voltage; and a second comparing means having one terminal connected to the first pin and a second reference voltage having a lower value than the first reference voltage connected to the other terminal. , comprising an alarm means for issuing an alarm upon receiving the outputs of the first comparison means and the second comparison means, when the measurement connection means is correctly fitted to the connector of the microprocessor; hand,
When the power to the device under test is not turned on, the voltage at one terminal of the second comparison means is lower than the second reference voltage connected to the other terminal, and the power to the device under test is turned on. when the voltage at one terminal of the first comparing means is higher than the first reference voltage connected to the other terminal, and the measuring connecting means is properly mated to the connector of the microprocessor. If not, the voltage at one terminal of the first comparing means is lower than the first reference voltage connected to the other terminal, and at the same time the voltage at one terminal of the second comparing means is lower than the first reference voltage connected to the other terminal. An erroneous connection detection circuit characterized in that the voltage is higher than the second reference voltage connected to the other terminal. 2. The erroneous connection detection circuit according to claim 1, wherein the alarm means is a display section of the measuring instrument. 3. The alarm means has a gate for taking an AND, in which the output of the first comparison means is applied to one terminal through an inverter, and the output of the second comparison means is applied to the other terminal, and the output of this gate. 2. The erroneous connection detection circuit according to claim 1, further comprising an alarm element driven by the erroneous connection detection circuit. 4. The erroneous connection detection circuit according to claim 3, wherein the alarm element emits an alarm sound. 5. The erroneous connection detection circuit according to claim 3, wherein the alarm element is a light emitting element.