Data transfer device

Abstract

A data transfer device according to one embodiment of the present disclosure comprises one data transmitting unit having a transmitting port, and a data receiving group having n receiving units, from a first receiving unit to an nth receiving unit (n≧2), wherein the transmitting port of the data transmitting unit is configured to serially transmit data respectively received by the n receiving units, and the ith receiving unit (2≦i≦n-1) has an input port and a data port, wherein the input port of the ith receiving unit receives data from the data port of the (i-1)th receiving unit, and wherein the data port of the ith receiving unit transmits data excluding data that should be received only by the ith receiving unit from the data received by the input port of the ith receiving unit.

Description

[Technical field]

[0001] The present disclosure relates to a data transfer device. [Background technology]

[0002] In recent years, high-resolution displays such as 4K and 8K have come into practical use. Because such displays have a large number of pixels, if signals were to be sent directly to each pixel independently, the number of wires between the display and the semiconductor chip that controls the image would be extremely large.

[0003] For this reason, efforts have been made to reduce the number of wirings, such as by standardizing the clock signal that transfers data for each pixel (see JP 2011-128535 A) or by serializing the data to reduce the number of data signals (see JP 8-10166 A). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-128535 A [Patent Document 2] Japanese Patent Application Publication No. 8-10166 Summary of the Invention [Problem to be solved by the invention]

[0005] Since the number of signals that can be reduced by sharing the clock signal is limited, generally, the number of data signals is reduced by serializing the data, either alone or in combination. For example, if you want to maintain the data transfer speed after serializing the data of four signal lines, you will need to transfer the data at four times the frequency. When transferring data at such high speeds, power consumption tends to increase significantly.

[0006] The present disclosure has been made in light of the above-mentioned circumstances, and has an object to provide a data transfer device that reduces the number of data signals while suppressing an increase in power consumption. [Means for solving the problem]

[0007] A data transfer device according to an embodiment of the present disclosure includes one data transmission unit having a transmission port, and a data reception group having n reception units from a first reception unit to an nth reception unit (n≧2), wherein the transmission port of the data transmission unit is configured to serially transmit data captured by each of the n reception units, the first reception unit has an input port and a data port, the input port of the first reception unit receives data from the transmission port of the data transmission unit, and the data port of the first reception unit selects only data received by the first reception unit from the data received by the input port of the first reception unit. the i-th receiver unit (2≦i≦n-1) has an input port and a data port, the input port of the i-th receiver unit receives data from the data port of the (i-1)-th receiver unit, and the data port of the i-th receiver unit is configured to transmit data excluding data that should be received only by the i-th receiver unit from the data received by the input port of the i-th receiver unit, and the n-th receiver unit has an input port, and the input port of the n-th receiver unit is configured to receive data from the data port of the (n-1)-th receiver unit. Effect of the Invention

[0008] The data transfer device according to the present disclosure can reduce the number of data signals while suppressing an increase in power consumption. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing a module configuration of a data transfer device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a block diagram showing the data transmission and reception relationship of the receiving unit of FIG. [Diagram 3]FIG. 3 is an example of a timing chart of data exchange in FIG. [Figure 4] FIG. 4 is a block diagram showing the configuration of an automatic discrimination mechanism of the receiving unit of FIG. [Diagram 5] FIG. 5 is a block diagram showing an example of the configuration of a data transfer system using the data transfer device of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Description of the embodiments of the present disclosure] (1) A data transfer device according to an embodiment of the present disclosure includes one data transmission unit having a transmission port, and a data reception group having n reception units, from a first reception unit to an nth reception unit (n≧2), wherein the transmission port of the data transmission unit is configured to serially transmit data captured by each of the n reception units, the first reception unit has an input port and a data port, the input port of the first reception unit receives data from the transmission port of the data transmission unit, and the data port of the first reception unit receives only data from the data received by the input port of the first reception unit. the i-th receiver unit (2≦i≦n-1) has an input port and a data port, the input port of the i-th receiver unit receives data from the data port of the (i-1)-th receiver unit, and the data port of the i-th receiver unit is configured to transmit data excluding data that should be received only by the i-th receiver unit from the data received by the input port of the i-th receiver unit, and the n-th receiver unit has an input port, and the input port of the n-th receiver unit is configured to receive data from the data port of the (n-1)-th receiver unit.

[0011] The data transfer device serially outputs data to be transmitted from a transmission port to n reception units, thereby making it possible to reduce the number of data signals between the data transmission unit and the data reception group. Also, in the data transfer device, the data port of the ith reception unit transmits data that is the data received by the input port of the ith reception unit, excluding data that should only be received by the ith reception unit. Therefore, compared to the case where the data is not excluded, the signal change at the data port of the ith reception unit can be reduced more than the signal change at the input port of the ith reception unit, thereby making it possible to prevent an increase in power consumption. Here, "data that should only be received by the ith reception unit" means data that does not need to be transmitted to the (i+1)th reception unit among the data received by the ith reception unit.

[0012] (2) In the data transfer device of (1) above, data transmission from the transmitting port is preferably performed at a constant data rate, and the data rate of data transmission at the data port of the jth receiving unit (1≦j≦n-1) is lower than the data rate of data reception at the input port of the jth receiving unit. By reducing the data rate of data reception at the data port of the jth receiving unit in this manner, power consumption due to signal changes in data can be reduced. Here, "data rate" refers to the number of bits of data transmitted and received per unit time (e.g., 1 second).

[0013] (3) In the data transfer device of (2) above, it is preferable that the data length of the data taken in by each of the n receiving units is configured to be equal, and that the data transmission from the data port of the jth receiving unit is performed at a rate that is (nj) / n times the data rate of the data transmission from the transmitting port. By configuring the data transmission from the data port of the jth receiving unit in this manner, it is possible to reduce power consumption while stably acquiring data. Here, "data taken in" (by a receiving unit) is synonymous with data received only by the corresponding receiving unit.

[0014] (4) In the data transfer device according to any one of (1) to (3), the data of the transmission port may be data taken in by each of the n receiving units arranged in descending order of the number i of the receiving units. By configuring in this way, it is easy to align the timing of the data taken in by each of the n receiving units.

[0015] (5) In the data transfer device according to any one of (1) to (4) above, the n receiving units may have an automatic discrimination mechanism capable of recognizing their own number i. In this way, the n receiving units have an automatic discrimination mechanism capable of recognizing their own number i, making it easy to perform initial setting.

[0016] (6) In the data transfer device of (5) above, the automatic discrimination mechanism may have a transfer start signal indicating the start of transfer to itself, a number input signal indicating the number i of the receiving unit to receive, a number register for holding the number input signal when the transfer start signal 41 indicates the start of transfer, a transfer output signal indicating the start of transfer to the next stage, and a number output signal indicating the number (i+1) of the receiving unit to receive at the next stage, and may be controlled so that the transfer output signal indicates the start of transfer after receiving the transfer start signal. By configuring the automatic discrimination mechanism in this way, a stable communication state can be ensured early, especially in a system performing high-speed communication.

[0017] [Details of the embodiment of the present disclosure] A data transfer device according to an embodiment of the present disclosure will be described below.

[0018] 1 includes one data transmitting unit 10 and a data receiving unit 20. The data transferring device 1 can be configured with a circuit such as an LSI.

[0019] <Data transmission section> The data transmitting unit 10 has three input ports 11 and one transmitting port 12 .

[0020] The three input ports 11 receive data to be received by three receiving units 30, which will be described later.

[0021] The data transmitting unit 10 is configured to serially transmit the data taken in by each of the three receiving units 30 from the transmitting port 12. Specifically, the input data input from the three input ports 11 is converted from parallel to serial and transmitted from the transmitting port 12. At this time, in order to prevent a decrease in the data transfer rate, it is preferable that the data rate of the transmitting port 12 is 3p when the data rate of the input data is p. In other words, the frequency of the data transfer is multiplied.

[0022] In particular, when the data rate is high (the frequency of data transfer is high), it is advisable to use a CDR (Clock Data Recovery) transfer method in which a clock, which is a reference for data transfer, is further incorporated into the data signal. The data transfer device 1 can be suitably used for CDR signal transfer.

[0023] Here, since circuits for performing parallel-serial conversion, multiplication of data transfer frequency, and signal conversion to the CDR system are well known, detailed explanations will be omitted.

[0024] <Data reception group> The data receiving group 20 has three receiving units 30 (a first receiving unit 31, a second receiving unit 32, and a third receiving unit 33). Each of the three receiving units 30 has an input port , a data port 35, and an output port .

[0025] 2, the input port 34 of the first receiving unit 31 is configured to receive data from the transmitting port 12 of the data transmitting unit 10, and the data port 35 of the first receiving unit 31 is configured to transmit data obtained by excluding only the data to be received by the first receiving unit 31 from the data received by the input port 34 of the first receiving unit 31. The data to be received by the first receiving unit 31 is output to the output port 36 of the first receiving unit 31.

[0026] The input port 34 of the second receiving unit 32 is configured to receive data from the data port 35 of the first receiving unit 31, and the data port 35 of the second receiving unit 32 is configured to transmit data excluding only the data to be received by the second receiving unit 32 from the data received by the input port 34 of the second receiving unit 32. In addition, the data to be received by the second receiving unit 32 is output to the output port 36 of the second receiving unit 32.

[0027] An input port 34 of the third receiving unit 33 is configured to receive data from a data port 35 of the second receiving unit 32. In addition, the data to be received by the third receiving unit 33 is output to an output port 36 of the third receiving unit 33.

[0028] Here, the data processing of the data receiving group 20 will be described in detail.

[0029] As described above, the data received by the input port 34 of the first receiving unit 31 from the transmitting port 12 of the data transmitting unit 10 (data of the transmitting port 12) is serialized data taken in by each of the three receiving units 30 (the first receiving unit 31, the second receiving unit 32, and the third receiving unit 33). The data taken in by each of the three receiving units 30 may be 1 bit or multiple bits.

[0030] The data of the transmitting port 12 may include an identifier inserted therein to indicate which receiving unit 30 should receive the data. In this case, each receiving unit 30 can determine which data to receive based on this identifier.

[0031] Alternatively, the data in the transmission port 12 may be arranged in a predetermined order. In this case, each receiver 30 can determine which data to receive based on the arranged position of the data. Since this method does not require the addition of an identifier, data transfer can be performed efficiently. In this case, the data to be taken in by each of the three receivers 30 may be arranged in descending order of the number i of the receiver 30.

[0032] In addition, it is preferable that the data transmission from the transmitting port 12 is performed at a constant data rate, and further, the data length of the data taken in by each of the three receiving units 30 is configured to be equal. Below, as shown in R1-IN (DR3) in Fig. 3, the data rate of the data transmission from the transmitting port 12 is constant at P (period T = 1 / P), the data length of each receiving unit 30 is 3 bits, and the data is arranged in descending order of number i (the data from the third receiving unit 33, the data from the second receiving unit 32, and the data from the first receiving unit 31), but this does not mean that the data of the transmitting port 12 of the data transfer device 1 is limited to these conditions.

[0033] In the data transfer device 1, the data rate of data transmission at the data port 35 of the jth receiver (1≦j≦2) is lower than the data rate of data reception at the input port 34 of the jth receiver. By reducing the data rate of data reception at the data port 35 of the jth receiver in this manner, it is possible to reduce power consumption due to changes in the data signal. Furthermore, when the data transfer device 1 is configured with a circuit, it is possible to design the circuit area to be small for the receiver with a lower data rate, and in this case, it is possible to reduce the cost of the data transfer device 1.

[0034] In particular, when n receivers 30 are provided, it is preferable that the data transmission of the data port 35 of the jth receiver is performed at a rate (nj) / n times the data rate P of the data transmission of the transmission port 12. By configuring the data transmission of the data port 35 of the jth receiver in this manner, it is possible to stably acquire data while reducing power consumption. In the data transfer device 1 shown in FIG. 1, n=3, so that the data rate of the data port 35 of the first receiver 31 (j=1) is 2 / 3P (=(3-1) / 3×P; the period is 1.5T), and the data rate of the data port 35 of the second receiver 32 (j=2) is 1 / 3P (=(3-2) / 3×P; the period is 3T), as shown in FIG. 3. For example, when the data rate of the data transmission of the transmission port 12 is 4.5Gbps, the data rate of the data port 35 of the first receiver 31 is 3.0GBps, and the data rate of the data port 35 of the second receiver 32 (j=2) is 1.5GBps. The following description will be given by taking as an example a case where this data rate relationship exists.

[0035] Generally, the data transfer period determined by the data rate may have periodic fluctuations such as delays and jitters, making transfers between different data rates unstable. To ensure stable transfers between different data rates, it is recommended to leave a margin of 20% or less for the (nj) / n times data rate. Specifically, for the (nj) / n times data rate, it is recommended to set the data rate to be between (nj) / n times or more and (nj) / n times x 1.2 or less.

[0036] As described above, the input port 34 of the first receiving unit 31 receives the data shown as R1-IN in Fig. 3 in synchronization with the period T. In Fig. 3, the parentheses for each signal indicate a label indicating the data rate, with DR3 being a data group of 4.5 Gbps (period T), DR2 being a data group of 3.0 Gbps (period 1.5T), and DR1 being a data group of 1.5 Gbps (period 3T).

[0037] The first receiver 31 outputs data R1-OUT to be received by the first receiver 31 from this R1-IN to the output port 36 of the first receiver 31. This R1-OUT can be performed in synchronization with the 3T period of DR1. Of R1-IN, data #1 to be received by the first receiver 31 is received in the last three periods. Therefore, as shown in FIG. 3, R1-OUT is output in synchronization with the 3T period of DR1 after data #1 has been received.

[0038] Furthermore, the first receiving unit 31 transmits data R1-D, which is data R1-IN received by the input port 34 of the first receiving unit 31 but data that should only be received by the first receiving unit 31, to the data port 35. This R1-D is output in synchronization with the 1.5T period of DR2. Since the data of R1-IN transmitted to the data port 35 is data for the first six periods, R1-D is output in synchronization with the 1.5T period of DR2 immediately after the input port 34 of the first receiving unit 31 starts receiving.

[0039] Since the input port 34 of the second receiving unit 32 receives data from the data port 35 of the first receiving unit 31, R2-IN becomes the same signal as R1-D and is synchronized with the period 1.5T of DR2.

[0040] The second receiving unit 32 outputs data R2-OUT to be received by the second receiving unit 32 from this R2-IN to the output port 36 of the second receiving unit 32. This R2-OUT can be performed in synchronization with the 3T period of DR1. Of the R2-IN, data #2 to be received by the second receiving unit 32 is received in the latter three periods. Therefore, as shown in Fig. 3, R2-OUT is output in synchronization with the 3T period of DR1 after data #2 has been received.

[0041] Furthermore, the second receiving unit 32 transmits data R2-D, which is data R2-IN received by the input port 34 of the second receiving unit 32, excluding only the data to be received by the second receiving unit 32, to the data port 35. This R2-D is output in synchronization with the 3T period of DR1. Since the data of R2-IN transmitted to the data port 35 is data for the first three periods, R2-D is output in synchronization with the 3T period of DR1 immediately after the input port 34 of the second receiving unit 32 starts receiving.

[0042] Since the input port 34 of the third receiver 33 receives data from the data port 35 of the second receiver 32, R3-IN becomes the same signal as R2-D and is synchronized with the period 3T of DR1.

[0043] At this stage, R3-IN contains only data to be received by the third receiver 33, so the R3-IN signal can be simply synchronized with the period 3T of DR1 and output as R3-OUT to the output port 36. In Fig. 3, the period can be adjusted so that the output is synchronized with the output ports 36 of the first receiver 31 and the second receiver 32.

[0044] <Automatic discrimination mechanism> It is preferable that the three receiving units 30 have an automatic discrimination mechanism capable of recognizing their own number i. In this way, the three receiving units 30 have an automatic discrimination mechanism capable of recognizing their own number i, so that initial setting can be easily performed.

[0045] For example, the automatic discrimination mechanism may be a method in which each receiving unit 30 is provided with a ROM and its own number i is obtained from data written in the ROM when the system is started, or a method in which the number i is given to a number recognition port provided in each receiving unit 30 when the system is started, thereby causing the receiving unit 30 to recognize the number i. However, particularly in the CDR method in which data is transferred at high speed with an embedded clock, there is a risk that the processing may be difficult or that the manufacturing costs of the LSI including the data transfer device 1 may increase.

[0046] Moreover, the above-mentioned method may increase manufacturing costs. More specifically, for example, if a ROM is provided in each receiving unit 30, the area of ​​the receiving unit 30 may increase. Even if the ROM is mounted on, for example, a printed wiring board outside the receiving unit 30, this leads to an increase in the size of the printed wiring board. Such an increase in area leads to an increase in manufacturing costs. Also, even in the case of fixing the external pins of the receiving unit 30 in order to give the number i to a port for number recognition provided in the receiving unit 30, a dedicated printed wiring board that matches the pattern for fixing the number i, for example, is provided, which increases the manufacturing cost of the printed wiring board.

[0047] In contrast, when the CDR method is adopted, for example, as shown in FIG. 4, the automatic discrimination mechanism 40 has a transfer start signal 41 indicating the start of transfer to itself, a number input signal 42 indicating the number i of the receiving unit 30 to receive, a number register 43 that holds the number input signal 42 when the transfer start signal 41 indicates the start of transfer, a transfer output signal 44 indicating the start of transfer to the next stage, and a number output signal 45 indicating the number (i+1) of the receiving unit 30 to receive at the next stage, and is controlled so that the transfer output signal 44 indicates the start of transfer after receiving the transfer start signal 41.

[0048] Explaining the operation of the automatic discrimination mechanism 40 in Fig. 4, first, in the initial state, the first receiving unit 31 has a transfer output signal 44 that is inactive, and a number output signal 45 that is the value obtained by adding 1 to the number register 43 is output. In this state, the first receiving unit 31 receives from the outside that the transfer start signal 41 is active and that the number input signal 42 is 1. When received from the outside, the number input signal 42 is always 1. The transfer start signal 41 means that the automatic discrimination mechanism 40 is started, and is active only for one period.

[0049] When the transfer start signal 41 becomes active, the first receiving unit 31 holds the value of the number input signal 42 in the number register 43. That is, the number register 43 becomes 1, and the number output signal 45 adds 1 to this to become 2. After that, the transfer output signal 44 is made active for only one cycle.

[0050] The transfer start signal 41 of the second receiving unit 32 is connected to the transfer output signal 44 of the first receiving unit 31, and the number input signal 42 of the second receiving unit 32 is connected to the number output signal 45 of the first receiving unit 31. At this time, the second receiving unit 32 operates in the same manner as the first receiving unit 31, and upon receiving that the transfer output signal 44 of the first receiving unit 31 has become active, the second receiving unit 32 holds 2 in the number register 43, then sets its own number output signal 45 to 3 and activates the transfer output signal 44.

[0051] The third receiving unit 33 is configured in a similar manner, and the number register 43 thereof holds the value 3.

[0052] In this manner, each receiving unit 30 can be made to recognize its own number i. By configuring the automatic discrimination mechanism 40 in this manner, it becomes possible to quickly ensure a stable communication state, particularly in a system that performs high-speed communication. Furthermore, in this automatic discrimination mechanism 40, it is possible to make each receiving unit 30 have the same configuration, which in turn makes it possible to suppress manufacturing costs.

[0053] <Advantages> The data transfer device 1 serially outputs data to be transmitted from the transmission port 12 to the three reception units 30, thereby making it possible to reduce the number of data signals between the data transmission unit 10 and the data reception group 20. Furthermore, in the data transfer device 1, the data port 35 of the i-th reception unit 30 transmits data obtained by excluding data that should be received only by the i-th reception unit 30 from the data received by the input port 34 of the i-th reception unit 30. Therefore, compared to the case where the data is not excluded, the signal change at the data port 35 of the i-th reception unit 30 can be reduced more than the signal change at the input port 34 of the i-th reception unit 30, making it possible to prevent an increase in power consumption.

[0054] [Other embodiments] The above-mentioned embodiment does not limit the configuration of the present disclosure. Therefore, the above-mentioned embodiment may omit, replace, or add components of each part of the above-mentioned embodiment based on the description in this specification and common technical knowledge, and it should be interpreted that all of them belong to the scope of the present disclosure.

[0055] In the above embodiment, the receiving group has three receiving units, but the number of receiving units is not limited to three and may be two or four or more. When the number of receiving units is n (n≧2), the n receiving units have an input port and a data port, the data transmitting unit is configured to serially transmit data taken in by each of the n receiving units from the transmitting port, the input port of the first receiving unit is configured to receive data from the transmitting port, the data port of the first receiving unit is configured to transmit data obtained by excluding data to be received only by the first receiving unit from data received by the input port of the first receiving unit, the input port of the i-th receiving unit (2≦i≦n-1) receives data from the data port of the (i-1)th receiving unit, the data port of the i-th receiving unit is configured to transmit data obtained by excluding data to be received only by the i-th receiving unit from data received by the input port of the i-th receiving unit, and the input port of the n-th receiving unit is configured to receive data from the data port of the (n-1)th receiving unit.

[0056] The number of receivers is preferably 3 to 8. If the number of receivers is less than the lower limit, the number of data signals between the transmitter and the receiver group may not be sufficiently reduced. Conversely, if the number of receivers is more than the upper limit, the period of data transfer between the transmitter and the receiver group may become too short, making stable communication difficult.

[0057] In the above embodiment, the third receiver, which is the last of the three receivers, has a data port, but the data port at the last stage can be omitted. On the other hand, if the third receiver has a data port, each receiver can have the same configuration, which has the advantage that the design and expansion of the data transfer device disclosed herein is easier.

[0058] In the above embodiment, a case has been described in which each of the three receiving units has an output port, but the output ports are not essential components, and the present disclosure also intends to provide a data transfer device in which some or all of the output ports are omitted.

[0059] In the above embodiment, the case has been described where the number of input ports of the transmitter matches the number of receivers, but the number of input ports of the transmitter and the number of receivers do not necessarily have to match and may be different. For example, the number of input ports of the transmitter may be four and the number of receivers may be three. In this case, when data is input to each input port of the transmitter at a data rate D1 and output from the transmission port of the transmitter at a data rate D2, the data rate can be determined so that, for example, D1×4=D2 holds true.

[0060] The data transfer device can be used in parallel. That is, it is possible to construct a data transfer system including a plurality of the data transfer devices arranged in parallel. For example, as shown in Fig. 5, when a data transfer system 100 is constructed by arranging two data transfer devices 1 of Fig. 1 in parallel, six data can be transferred through two signal lines. [Industrial Applicability]

[0061] The data transfer device according to the present disclosure can reduce the number of data signals while suppressing an increase in power consumption. [Explanation of symbols]

[0062] 1 Data transfer device 10 Data transmission unit 11 Input Ports 12 Outbound Port 20 Data Reception Group 30 Receiving section 31 First Receiving Unit 32 Second Receiving Unit 33 Third Receiving Unit 34 Input Ports 35 Data Port 36 Output Ports 40 Automatic discrimination mechanism 41 Transfer start signal 42 Number input signal 43 Number Register 44 Transfer output signal 45 Number output signal 100 Data Transfer System

Claims

1. a data transmitter having a transmission port; a data receiving group having n receiving units from a first receiving unit to an nth receiving unit (n≧2); Equipped with a transmission port of the data transmission unit is configured to serially transmit the data captured by each of the n reception units; the first receiving unit has an input port and a data port, the input port of the first receiving unit receives data from the transmission port of the data transmission unit, and the data port of the first receiving unit is configured to transmit data obtained by excluding only data to be received by the first receiving unit from the data received by the input port of the first receiving unit; In the case where n≧3, the i-th receiver (2≦i≦n−1) has an input port and a data port, the input port of the i-th receiver receives data from the data port of the (i−1)-th receiver, and the data port of the i-th receiver transmits data excluding data to be received only by the i-th receiver from the data received by the input port of the i-th receiver; the n-th receiver has an input port, the input port of the n-th receiver configured to receive data from a data port of the (n-1)-th receiver; The data transmission from the transmitting port is performed at a constant data rate, A data transfer device in which the data rate of data transmission at the data port of the jth receiver (1≦j≦n−1) is lower than the data rate of data reception at the input port of the jth receiver.

2. The data lengths of the data taken in by each of the n receiving units are configured to be equal, 2. The data transfer device according to claim 1, wherein data transmission from the data port of said jth receiving unit is performed at a rate that is (nj) / n times the data rate of data transmission from said transmitting port.

3. 3. The data transfer device according to claim 1, wherein the data at said transmission port is data taken in by each of said n receiving units arranged in descending order of the number i of said receiving units.

4. 3. The data transfer device according to claim 1, wherein said n receiving units each have an automatic discrimination mechanism capable of recognizing its own number i.

5. The automatic discrimination mechanism is a transfer start signal indicating the start of transfer to itself; A number input signal indicating the number i of the receiving unit to receive the signal; a number register for holding a number input signal when the transfer start signal indicates the start of transfer; A transfer output signal indicating the start of transfer to the next stage; A number output signal indicating the number (i+1) of the receiving unit to be received by the next stage; having 5. The data transfer device according to claim 4, wherein said transfer output signal is controlled to indicate the start of transfer after said transfer start signal is received.