JP3116440B2 - Signal transmission circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission circuit, and more particularly to a signal transmission circuit in which output signals from a plurality of driver circuits are wired-ORed through daisy-chained signal lines and input to a receiver circuit.

[0002]

2. Description of the Related Art Conventionally, as a signal transmission circuit of this type, an open collector output TTL circuit is used as a switch circuit of an individual driver circuit, for example, and wired OR through a daisy chain connection signal line. Signal transmission circuit.

[0003]

In the above-described conventional signal transmission circuit, the output of each driver circuit is constituted only by a switch circuit. Therefore, when a wired OR operation is performed through a daisy chain connection signal line, the driver is not driven. The output of the circuit has a drawback that all switch circuits (driver circuits) can be turned off or only the other two states can be determined, and it is not possible to determine how many driver circuits are on.

[0004]

A signal transmission circuit according to the present invention includes a plurality of driver circuits each having means for connecting one end of a first resistor to a first reference potential in accordance with a signal to be transmitted. A signal line for daisy-chaining the plurality of driver circuits and word-ORing the output signal from the other end of each of the first resistors, and a second resistor having one end connected to the second reference potential. Shin Ru and a receiver circuit having means for detecting the potential at the junction end and said signal line
In the signal transmission circuit, each of the plurality of driver circuits
The first resistor is used for weighting a corresponding driver circuit.
Has a resistance value corresponding to

In the above configuration, the means for detecting the potential of the connection point of the receiver circuit may include a plurality of comparison circuits for comparing a reference potential of a different predetermined voltage value with a potential of the connection point and outputting a result. It can be configured as a container .

[0006]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a first embodiment of the present invention. Each output is daisy chain connected signal line 2
, 1-2,..., 1-n connected to
, The switch circuits 11-1, 11-2,.
-N control circuit 13-1, ..., the 13-n signal from the resistor one end to the signal line 2 of the daisy chain connection is connected anti vessels 12-1, 12-2, ..., 12- The other end of n is connected to the ground potential which is the first reference potential. In the receiver circuit 3, comparator 34-1, resistor vessel 3 having one end connected to the second reference potential 32 of the reference voltage value Vref2
The potential of the connection point 35 between the other end of the signal line 1 and the daisy chain connection signal line 2 is compared with the reference voltage value Vref3 of the third reference potential 33-1.

Here, in the above configuration, the simultaneous ON state is set.
The principle of detecting the number of driver circuits will be described. Description
For simplicity, if the driver circuit has no weight
, That is, each of the resistors 12-1, 12-2,.
The case where all the resistance values of n are the same r1 will be described as an example.
You. It is assumed that the resistance value of the resistor 31 is r2.
Now, the driver circuits 1-1 and 1-2, ..., 1-n in the switching circuits 11-1 and 11-2, ..., of the 11-n, the number of on-state and m (m ≦ n) Ignoring the voltage drop of the switch circuit in the ON state, the connection point 3 of the receiver circuit 3
5 (input potential of the comparator 34-1) is r1.Vre
f2 / (r1 + mr2). Therefore, by appropriately selecting the reference voltage value Vref3 of the third reference potential 33-1,
It is possible to detect the number m of driver circuits in the ON state.

The feature of the present invention is that the driver circuit
The number of driver rounds according to the weight.
Can be detected at the same time if the road is on.
And there. Therefore, each of the driver circuits 1-1, 1-2,
, 1-n resistors 12-1, 12-2, ..., 12-n
Are respectively set to values corresponding to the weights.
For example, when the weights of the driver circuits 1-1 and 1-2 are set to 1,
The weights of the driver circuits 1-3,..., 1-n are halved.
And the resistance values of the resistors 12-1 and 12-2 as r1,
The resistance values of the arresters 12-3,..., 12-n are 2r1.
You.

In this configuration, the driver circuit 1-1 or
Is the receiver if only one of 1-2 is on
The potential of the connection point 35 of the circuit 3 is r1.Vref2 / (r1 + r
2) Also, the driver circuits 1-3,.
If only one of them is on,
The potential of the connection point 35 with the case of only one
R1 · Vref2 / (r1 + r2 / 2), r1 · Vref2
/ (R1 + r2). Therefore, the third reference potential 33
By properly selecting the reference voltage value Vref3 of −1,
Either one of the inverter circuits 1-1 and 1-2 is ON.
To detect the state, driver circuit 1-3, ..., 1-n is any
One or more ON states can be detected.

In the above description, the driver circuit
Two combinations of road weights have been described.
Are the resistance values of the resistors 12-1, 12-2, ..., 12-n.
By appropriately combining the number of weighted combinations
Can be any set of 1 to n.

FIG . 2 is a circuit diagram of a second embodiment of the present invention. FIG. 2 differs from FIG. 1 in that each driver circuit 1-1,
1-2,..., 1-n first reference potentials 14-1, 14-
2,..., 14-n are not ground potentials but reference potentials of the reference voltage value Vref1, and the second reference potential of the receiver circuit 3 is the ground potential.

[0013] In this configuration, in the simultaneous ON state,
The principle of detecting the number of circuit circuits will be described. Simplify explanation
Therefore, if the driver circuit has no weight,
The resistance value of each of the resistors 12-1, 12-2, ..., 12-n
Are all the same r1. In addition,
It is assumed that the resistance value of the resistor 31 is r2. When the number of ON states among the driver circuits 1-1, 1-2,... The potential at point 35 is
mr2 · Vref1 / (r1 + mr2). Therefore, by appropriately selecting the reference voltage value Vref3 of the third reference potential 33-1, it is possible to detect the number m of the driver circuits in the ON state.

[0014] In this configuration, the feature of the present invention is:
Weight each driver circuit and weight its resistance
The operation in the case where the value is set according to the following will be described. For example,
As in the first embodiment, the driver circuits 1-1, 1
, 1-n, and the driver circuits 1-3,..., 1-n
If the weight of the resistors 12-1 and 12-2 is 1/2,
Let the resistance value be r1, and connect the resistors 12-3,.
Let the resistance value be 2r1.

[0015] Either driver circuit 1-1 or 1-2
If only the ON state, the connection point 35 of the receiver circuit 3
Is r2.Vref1 / (r1 + r2). Ma
One of the driver circuits 1-3, ..., 1-n
Only one is on, and only two are on
And the potential at the connection point 35 is r2.Vref1
/ (2r1 + r2), r2.Vref1 / (r1 + r2)
Become. Therefore, the reference voltage value V of the third reference potential 33-1
By appropriately selecting ref3, the driver circuits 1-1, 1
-2 detects the ON state of only one of the
Each of the circuits 1-3,..., 1-n has at least two ON states.
State can be detected.

[0016] In the above description, the driver circuit
Two combinations of road weights have been described.
Are the resistance values of the resistors 12-1, 12-2, ..., 12-n.
By appropriately combining the number of weighted combinations
Can be any set of 1 to n.

FIG . 3 is a circuit diagram showing a third embodiment of the receiver circuit of the present invention. The receiver circuit 30 of FIG. 3 is different from the receiver circuit 3 of FIG. 1 in that the potential of the connection point 35 between the resistor 31-1 and the daisy-chained signal line 2 is changed to the reference voltage Vref4 of the fourth reference potential 33-2. And a comparator 34-2 for comparison and collation.

In this configuration, the dry on
The principle of detecting the number of circuit circuits will be described. Simplify explanation
Therefore, if the driver circuit has no weight,
The resistance value of each of the resistors 12-1, 12-2, ..., 12-n
Are all the same r1. In addition,
It is assumed that the resistance value of the resistor 31 is r2. Now, the number of ON states of the switch circuits in each of the driver circuits 1-1, 1-2,..., 1-n is m1, m2 (m1 <m2 ≦
For n), and ignoring the voltage drop of the ON state, the potentials of the connection points 35, r1 · Vref2 / (r1 + m1 r
2), r1.Vref2 / (r1 + m2r2) . Supporting Tsu <br/> Te, third, by selecting the fourth reference voltage of the reference potential 33-1 and 33-2 Vref3, Vref4 appropriately detects the number m1, m2 of the driver circuit in the ON state And control according to them becomes possible.

[0019] In this configuration, the feature of the present invention is:
Weight each driver circuit and weight its resistance
The operation in the case where the value is set according to the following will be described. For example,
As in the first embodiment, the driver circuits 1-1, 1
, 1-n, and the driver circuits 1-3,..., 1-n
If the weight of the resistors 12-1 and 12-2 is 1/2,
Let the resistance value be r1, and connect the resistors 12-3,.
Let the resistance value be 2r1.

[0020] In this configuration, the driver circuits 1-1,
1-2, if only one is on, and both are off.
Of the connection point 35 of the receiver circuit 30 with respect to the case of the
Are r1 · Vref2 / (r1 + r2), r1 · V
ref2 / (r1 + 2r2). Also, the driver circuit 1
-3,..., 1-n
Connection point 3 between the case and the case where only two of them are on
5 are r1 · Vref2 / (r1 + r2 //
2), r1.Vref2 / (r1 + r2). Therefore,
Reference voltage values of third and fourth reference potentials 33-1 and 33-2
By appropriately selecting Vref3 and Vref4, the driver circuit
1-1 and 1-2 indicate only one of the ON state and both
ON state is detected respectively, and driver circuits 1-3,
, 1-n detect any two or more ON states
It becomes possible.

In the above description, the driver circuit
Two combinations of road weights have been described.
Are the resistance values of the resistors 12-1, 12-2, ..., 12-n.
By appropriately combining the number of weighted combinations
Can be any set of 1 to n. Further, the receiver circuit 30, a case has been described in the number of detected number m of the driver circuit in the ON state of the two pairs, the resistor 31 and the collector position of the connection point 35 between the signal line 2 of the daisy-chained
The number of detections can be set to an arbitrary set of 1 to n by combining any desired number of detection comparison means.
Further, the receiver circuit 30 can be replaced with the receiver circuit 3 of FIG. 2 by setting the second reference potential 32 to the ground potential.

[0022]

As described above, according to the present invention, in a plurality of driver circuits wired or wired via daisy-chain-connected signal lines, a resistor connected to the signal line is used.
And the value corresponding to the weight of the driver circuit.
A resistor having one end connected to the second reference potential in a receiver circuit connected to the same signal line , wherein the resistor and the first reference potential are turned on / off by a switch circuit. By detecting the potential at the connection point between the driver circuit and the signal line, there is an effect that the number of driver circuits in the ON state in a combination according to the weighting can be easily detected.

Further , in the receiver circuit, the number of detections can be set to an arbitrary set by detecting the potential at the connection point between the resistor having one end connected to the second reference potential and the signal line with a plurality of detection potentials. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention.

[Explanation of symbols]

1-1, 1-2, 1-3,..., 1-n driver circuit 2 daisy chain connection signal line 3, 30 receiver circuit 11-1, 11-2, 11-3,. 12-1, 12-2, 12-3, ..., 12-n, 31
, 13-n Control circuit 14-1, 14-2, ..., 14-n First reference potential 32 Second reference potential 33-1 Third Reference potential 33-2 Fourth reference potential 34-1 and 34-2 Comparator

Claims (2)

(57) [Claims] 1. A plurality of driver circuits each having means for connecting one end of a first resistor to a first reference potential in accordance with a signal to be transmitted by each of the plurality of driver circuits, and daisy-chaining the plurality of driver circuits. A signal line for wired-ORing an output signal from the other end of each of the first resistors, and a connection point between the other end of the second resistor having one end connected to a second reference potential and the signal line. in the signal transmission circuit and a receiver circuit having means for detecting a potential, the first resistor of each respective of said plurality of driver circuits,
Has a resistance value according to the weight of the corresponding driver circuit
Signal transmission circuit, characterized in that that. 2. The means for detecting the potential of the connection point of the receiver circuit comprises a plurality of comparators each of which compares a reference potential of a different predetermined voltage value with a potential of the connection point and outputs a result. The signal transmission circuit according to claim 1, wherein: