JP4036121B2 - Transmission interface converter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission interface, and more particularly to a conversion device for connecting modules having different specifications.
[0002]
[Prior art]
A standard interface as a transmission means between LSIs using a large-scale integrated circuit (LSI) as a transmission means includes an MII (Media Independent Interface) specification, but an RMII (Reduced Media Independent Interface) specification. Things are also being standardized and used.
These are generally used as transmission means between a link LSI and a PHY LSI. As shown in FIG. 3A, transmission between modules of MII specifications and between RMII specifications as shown in FIG. In general, transmission is performed by the module.
However, depending on the specifications of the LSI being used, it is necessary to perform transmission between the MII specification module and the RMII specification module. In such a case, (c) a conversion module 3 such as an FPGA is interposed as shown in FIG. Therefore, it is necessary to convert according to each interface specification.
[0003]
Such a connection configuration has been increased by adopting Ethernet (registered trademark) in response to the use and openness of the Internet technology as a monitoring control network, for example.
When Ethernet (registered trademark) is applied to the field of monitoring and control, real-time performance is one of the important factors. In this case, since a frame collision occurs depending on the line port (port interface) used, a conversion module for conversion of specifications is provided to prevent the collision.
Basically, RMII is a specification created for the purpose of reducing the number of MII-specific signal lines, and thus can be converted into each interface specification.
[0004]
[Patent Document 1]
Special Table 2002-540725 Figure 1
[0005]
[Non-Patent Document 1]
IEEE 802.3ab standard [0006]
[Problems to be solved by the invention]
As interface specification conversion, generally, conversion from the MII specification to the RMII specification and conversion from the RMII specification to the MII specification are respectively performed on the transmission side and the reception side for transmission.
For example, in FIG. 4A, the conversion module 3 converts the transmission side from the RMII specification to the MII specification, and converts the reception side from the MII specification to the RMII specification for transmission.
[0007]
4A, when the system is, for example, a switching hub, the module 1 corresponds to an Ethernet (registered trademark) switching unit, and a plurality of line ports are connected as a link configuration. (A) The figure shows one line port as a representative, and module 2 and later are modules in the line port. 4 is a connector, and 5 is a relay means such as a hub, to which a 10BASE-T / 100BASE-TX network is connected.
In the case of this configuration, since the transmission line and the reception line are separate, there is no problem if the bidirectional conversion is simply performed.
[0008]
However, as shown in FIG. 4 (b), when the line port is connected to 10BASE-5, after the interface 6 (repeater), there is one transmission / reception line, which is a full half duplex system. Yes. The data transmitted at the time of transmission is always returned as data to the receiving side by the repeater 6. Therefore, when the MIIs are connected, it is possible to ignore this return data by setting the LSI of the link 1, but when the LSI of the module 1 is RMII specification as shown in FIG. If the reception is recognized, it will be recognized as a collision and transmission will be stopped.
[0009]
The reason is that in the case of the MII specification, there is a signal that conveys a collision. However, in the case of the RMII specification, the collision is recognized by recognizing the signal returned during transmission as a reception valid signal, and transmitting. It becomes a stop phenomenon.
Therefore, in the configuration as shown in FIG. 4B, reception is possible, but transmission is impossible.
[0010]
An object of the present invention is to provide a conversion device that requires conversion means for connection between interfaces of different specifications and prevents collision recognition when 10BASE-5 is connected to a transmission line. .
[0011]
[Means for Solving the Problems]
In the first aspect of the present invention, an MII specification module and an RMII specification module are connected to a transmission interface via a transmission line, and a conversion module for conversion of specifications is connected between the two modules. In the transmission interface connected to 10BASE-5,
The conversion module includes a timer that starts an operation when receiving a transmission signal from the RMII specification module and outputs a signal for a predetermined time, and a reception impossibility determination unit that blocks reception of the RMII specification module on condition that the timer signal is received. It is characterized in that it is provided.
[0012]
According to a second aspect of the present invention, the reception disable signal from the reception disable determination unit is output to a conversion unit that converts the MII specification provided in the conversion module into an RMII specification to prevent reception. is there.
[0013]
A third aspect of the present invention is characterized in that the predetermined time of the timer is set to a time until the next normal signal is transmitted, covering the maximum time when the transmission signal is turned back. is there.
[0014]
A fourth aspect of the present invention is characterized in that a gate unit is provided in a transmission path on the receiving side between the conversion module and 10BASE-5, and a reception disabled signal from the reception disabled determination unit can be output to the gate unit. To do.
[0015]
A fifth aspect of the present invention is characterized in that the gate portion is provided between the MII specification module and 10BASE-5.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing an embodiment of the present invention. Like FIG. 4B, the LSI specifications of the modules constituting the interfaces 1 and 2 are different. Here, the specification of the module 1 is RMII. The specification of module 2 is MII. Further, 10BASE-5 is connected to the interface (repeater) 6. Reference numeral 4 denotes an interface connector, and reference numeral 10 denotes a conversion module. The conversion module 10 is configured as shown in FIG.
[0017]
In FIG. 1B, reference numeral 11 denotes a first conversion unit, which receives the RMII specification transmission signal transmitted from the module 1, converts it to an MII specification signal, and transmits it to the module 2. Further, when the conversion unit 11 receives the transmission valid from the module 1, the conversion unit 11 outputs the signal a to the reception impossibility determining unit 12 and the timer unit 13 set to the time limit α. The setting time α is set so as to cover the maximum time for the repeater 6 of 10BASE-5 to return the transmission data, and until the time when the next normal reception data may be sent. The These times can be easily calculated from the standard. The reception impossibility determination unit 12 outputs the reception impossibility signal b to the second conversion unit 14 only for α time after receiving the transmission valid signal a.
[0018]
The second converter 14 receives the transmission signal of the MII specification transmitted from the module 2, converts it into a signal of the RMII specification, and outputs it to the module 1. At this time, if the reception disable signal b is input, reception from the module 2 is disabled.
Reference numeral 15 denotes a collision recognition / transmission unit that discriminates a collision call from the module 2 and transmits it to the module 1.
[0019]
The operation of the apparatus configured as described above will be described.
[0020]
When the transmission signal of the specification RMII is output from the module 1, the conversion module 10 converts the RMII into the MII specification and transmits it to the module 2. In the module 2, the signal is sent to 10BASE-5 via the connector 4 and the repeater 6. The transmission signal from the module 2 is immediately turned back by the repeater 6, and returned to the conversion module 10 through the module 2 as an MII reception signal. .
[0021]
On the other hand, in the conversion module 10, when the RMII transmission signal from the module 1 is received, the first conversion unit 11 outputs the transmission valid signal a to the timer unit 13, and this timer is driven so that reception is not possible for a certain period of α. A signal is output to the determination unit 12.
Based on the signal from the timer, the determination unit 12 generates a reception disable signal b to the second conversion unit 14 and closes the signal input gate from the module 2 to disable the signal reception. Therefore, the return module 10 does not transmit the return signal from the repeater 6 to the module 1 via the second conversion unit 14 during signal transmission from the first conversion unit 11 to the module 2, and the collision recognition phenomenon. Does not occur.
[0022]
Further, the collision recognition transmission unit 15 determines a collision call signal from the module 2 and asserts a reception valid signal to the module 1 so that the module 1 can recognize the collision.
[0023]
FIG. 2 shows another embodiment. As shown in FIG. 5A, a gate unit 20 such as a buffer with a gate control is provided in the reception route of the module 1 such as between the module 2 and the conversion module 10 ′ or between the module 2 and the connector 4. As shown in FIG. 5C, the gate unit 20 is configured not to send the reception signal to the subsequent stage by closing the gate when the reception disable signal b is “present”.
Further, the reception impossibility determining unit 12 of the conversion module 10 ′ determines an α time from when the timer 13 is kicked until the time is up, and outputs a reception impossibility signal b. Applied to the gate.
Others are the same as FIG.
[0024]
In this embodiment, the module 1 can transmit a signal normally without recognizing a collision as in FIG. 1, but the receiving path between the module 2 and the repeater 6 (between 2 and 4 in FIG. 2). By inserting the gate section 20 into the MII specification, an extra received signal does not reach the MII specification module 2 itself, so that the module 2 itself can confirm reception to itself at the time of transmission. Therefore, only a valid received signal can be sent to the conversion module 10 ′, and the module 1 can receive the signal converted to the RMII specification.
[0025]
【The invention's effect】
As described above, according to the present invention, when the module of MII and RMII specifications are connected via the transmission path and the conversion module, and 10BASE-5 is connected to the transmission path of the MII specification module, it is received by the conversion module. An impossibility determining unit is provided, and at the time of transmission from the RMII specification module by this determination unit, reception on the RMII specification module side is prevented and collision is not recognized.
As a result, the RMII specification module can normally transmit a signal without recognizing a collision.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an embodiment of the present invention, where (a) is a system diagram and (b) is a configuration diagram of a conversion module.
2A and 2B are configuration diagrams showing a second embodiment of the present invention, in which FIG. 2A is a system diagram, FIG. 2B is a configuration diagram of a conversion module, and FIG. 2C is a configuration diagram of a gate unit;
FIG. 3 shows a configuration diagram of a conventional transmission interface, where (a) is a connection between MII specification modules, (b) is a connection between RMII specifications, and (c) is a connection between RMII and MII specifications. Connection diagram.
4A and 4B are configuration diagrams of a conventional transmission system, in which FIG. 4A shows a case where 10BASE-T / 100BASE-TX is connected to the transmission path of the MII specification module, and FIG. 4B shows a connection of 10BASE-5 to the transmission path of the MII module. Figure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... RMII specification module 2 ... MII specification module 3 ... Conversion module 4 ... Connector 6 ... Repeater 10,10 '... Conversion module 11 ... First conversion part 12 ... Reception impossible determination part 13 ... Timers 14, 14' ... Second conversion Part 15 ... Collision recognition transmission part 20 ... Gate part

Claims (5)

Transmission with MII specification module and RMII specification module connected to the transmission interface via a transmission line, a conversion module for conversion of specifications connected between both modules, and 10BASE-5 connected to the transmission line of the MII specification module In the interface,
The conversion module includes a timer that starts an operation when receiving a transmission signal from the RMII specification module and outputs a signal for a predetermined time, and a reception impossibility determination unit that blocks reception of the RMII specification module on condition that the timer signal is received. A transmission interface conversion device characterized by being provided in the above. 2. The transmission interface conversion according to claim 1, wherein the reception disable signal from the reception disable determination unit is output to a conversion unit that converts the MII specification provided in the conversion module to an RMII specification to prevent reception. apparatus. 3. The transmission interface according to claim 1, wherein the predetermined time of the timer is set to a time until a transmission signal is turned back and a time until a normal signal is sent next time is covered. Conversion device. 4. A reception unit transmission line between the conversion module and 10BASE-5 is provided with a gate unit, and a reception disable signal from the reception disable determination unit can be output to the gate unit. Transmission interface converter. 5. The transmission interface conversion apparatus according to claim 1, wherein the gate section is provided between the MII specification module and 10BASE-5.

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