JP6264758B2 - Optical transceiver - Google Patents

Description

  The present invention relates to an optical transceiver used in an optical communication system.

  In recent years, optical transceivers used in optical communication systems have been required to have high functionality and small size. For example, an optical transceiver transmits and receives an optical signal in two-core bidirectional using four wavelengths in a wavelength band of 1300 nm. In this optical transceiver, the transmitting side performs electro-optical conversion at a data rate of 25 Gbps for each wavelength, and then combines four wavelengths to output one wavelength multiplexed signal, and the receiving side outputs one wavelength multiplexed signal. It receives it, demultiplexes it into four wavelengths, and performs photoelectric conversion at a data rate of 25 Gbps for each wavelength. Standards relating to the outer diameter, terminal arrangement, electrical characteristics, and optical characteristics of such optical transceivers are defined by MSA (Multi-Source Agreement) standard CFP (100G Form-factor Pluggable).

  In the case of CFP, an external host device and an optical transceiver are connected via an MDIO (Management Data Input / Output) bus. The MDIO bus is composed of two signal lines, a clock signal MDC and a data signal MDIO. Communication via this bus is performed in units of 64-bit data called frames, and there are four types of address setting, writing, and reading (two types) depending on the purpose. Which type is specified by the host device by the OP code in the frame.

  Here, the optical transceiver is required to have a function of detecting a loss of signal (LOS) and issuing a LOS signal as one of the communication state monitoring functions. In general, an optical transceiver has a built-in CPU when an optical receiver device (ROSA: Receiver Optical Sub-assembly) in which one photodiode and one transimpedance amplifier are mounted is used for each wavelength. Receives the LOS signal individually for each wavelength, identifies which wavelength the LOS has occurred, and sends an alarm signal to the host device via the dedicated signal line. On the other hand, in CFP, the alarm issuing time to the host device is defined as within 100 μsec from the occurrence of LOS, and the maximum frequency of MDC is 4 MHz.

  Currently, along with demands for higher speed and larger capacity of communication systems, there is a continuous demand for miniaturization of optical transceivers from the market. Specifically, studies on MSA standards such as CFP2 and CFP4, which are further miniaturized from CFP, are underway.

Japanese Patent No. 4657291

  In order to reduce the size of the optical receiving device (ROSA), it is effective to mount an optical demultiplexer, a plurality of (for example, four) photodiodes, and a transimpedance amplifier corresponding to a plurality of channels in one package. In this case, the signal lines for notifying the LOS signal to the built-in CPU need to be integrated into one because of the limitation on the number of terminals, and the built-in CPU is notified that LOS has occurred at at least one wavelength. However, the built-in CPU needs to read information stored in a register in the transimpedance amplifier using a serial bus or the like in order to know at which wavelength the LOS has occurred.

  On the other hand, when an external host device receives an alarm signal from the optical transceiver via a dedicated signal line, it reads the value of the MDIO register in the CPU via the MDIO bus to grasp the wavelength at which the LOS has occurred. Communication for this LOS occurrence notification is required to be performed in conformity with the above-mentioned standards such as CFP, but depending on the CPU register read processing time required with the downsizing of ROSA In some cases, the request cannot be met.

  Therefore, the present invention has been made in view of such a problem. Even when the device is downsized, an optical device capable of executing processing at high speed while ensuring consistency by notification of occurrence of LOS. An object is to provide a transceiver.

  In order to solve the above-described problem, an optical transceiver according to an aspect of the present invention has a duplexer that demultiplexes an optical input signal into a plurality of optical output signals having different wavelengths, and an abnormality in the plurality of optical output signals is detected. A memory circuit unit that stores abnormality information indicating an abnormality occurrence state for each of a plurality of optical output signals at a timing, and a microcomputer connected to the optical reception device via an alarm signal line and a communication bus The optical receiving device, when detecting an abnormality in at least one of the plurality of optical output signals, sends an alarm signal to the microcomputer via the alarm signal line, and prevents the occurrence of the abnormality. Corresponding abnormality information is stored in the storage circuit unit, and the microcomputer reads the abnormality information from the storage circuit unit via the communication bus when the alarm signal is received from the optical receiving device. It is.

  Alternatively, an optical transceiver according to another aspect of the present invention includes a duplexer that demultiplexes an optical input signal into a plurality of optical output signals having different wavelengths, and a detection circuit unit that detects an abnormality for each of the plurality of optical output signals. When the optical receiving device detects an abnormality in at least one of the plurality of optical output signals, the optical receiving device has a microcomputer connected to the optical receiving device via an alarm signal line. In addition, the abnormality occurrence state for each of the plurality of optical output signals is identified based on the abnormality information corresponding to the occurrence of the abnormality, and a pulse signal indicating the abnormality occurrence state for each of the plurality of optical output signals is transmitted via the alarm signal line. When the pulse signal is received from the optical receiving device, the microcomputer specifies an abnormality occurrence state for each of the plurality of optical output signals based on the pulse signal.

  According to the present invention, even when the device is downsized, it is possible to provide an optical transceiver capable of executing processing at high speed while ensuring consistency by an LOS occurrence notification.

1 is a block diagram showing a schematic configuration of an optical transceiver according to a first embodiment of the present invention. It is a block diagram which extracts and shows the connection structure between CPU13 of FIG. 1, and ROSA11. FIG. 3 is a sequence diagram showing a procedure of LOS signal notification operation between the optical transceiver 1 and the host device 50 of FIG. 1. It is a sequence diagram which shows the procedure of the LOS notification operation | movement between the optical transceiver 1 and the host apparatus 50 which concern on 2nd Embodiment of this invention. (A) is a timing chart showing the time waveform of the LOS signal transmitted from the ROSA 11 to the CPU 13 during the LOS notification operation, and (b) shows the time waveform of the LOS signal transmitted from the CPU 13 to the host device 50 during the LOS notification operation. It is a timing chart which shows. ROSA11 and the number of pulses of rectangular pulses P ₁ in the LOS signal set by according to the second embodiment, showing the correspondence between LOS generation state of each channel. It is a flowchart which shows the procedure of the LOS notification operation | movement in CPU13 which concerns on 2nd Embodiment. It is a block diagram which shows schematic structure of the optical transceiver which concerns on a comparative example. It is a block diagram which extracts and shows the structure by the side of the optical receiving device in the optical transceiver of another modification. It is a sequence diagram which shows the procedure of the notification operation | movement of the LOS signal of the optical transceiver which concerns on another modification.

  Embodiments of an optical transceiver according to the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

[First Embodiment]
FIG. 1 is a block diagram showing a schematic configuration of an optical transceiver according to the first embodiment of the present invention. The optical transceiver 1 is a device used for transmitting and receiving optical signals in an optical communication system, and includes an optical multiplexing function, an optical demultiplexing function, an optical-electrical mutual conversion function, an electrical waveform shaping function, and the like. As shown in the figure, the optical transceiver 1 is connected to an external host device 50 via a communication bus, and includes CDR (Clock Data Recovery) circuit units 3 and 5, LDD (Laser Diode Driver) circuit unit 7, It includes a TOSA (Transmitter Optical Sub-assembly) 9 that is an optical transmission device, a ROSA (Receiver Optical Sub-assembly) 11 that is an optical reception device, and a CPU 13 that is a microcomputer.

The TOSA 9 incorporates four laser diodes (hereinafter referred to as “LDs”) 15 that are four-channel light emitting elements and an optical multiplexer 17, and the four-channel LD 15 includes four electric sources from the outside. Based on the signal TX, optical signals having different wavelengths are generated, and the optical multiplexer 17 combines these optical signals and outputs them. The CDR circuit unit 3 receives, for example, four electrical signals TX having a data transfer rate of 10 Gbps and 25 Gbps from the outside, and shapes the waveforms of these electrical signals TX. The LDD circuit unit 7 receives the four electric signals TX from the CDR circuit unit 3, modulates the four LDs 15 based on the four electric signals, and outputs an optical signal. As a result, the optical signal O _out having a data transfer rate of 40 Gbps or 100 Gbps is output from the TOSA 9. The LDD circuit unit 7 also has a function of selectively blocking the output of optical signals from the four LDs 15 in accordance with a control signal from the CPU 13.

The ROSA 11 includes four photodiodes (hereinafter referred to as “PD”) 19, an optical demultiplexer 21, and a transimpedance amplifier (hereinafter referred to as “TIA”) 23, which are four-channel light receiving elements. The so-called “integrated ROSA”. The optical demultiplexer 21 receives an optical input signal O _in from the outside, and demultiplexes the optical input signal O _in into optical output signals of four channels having different wavelengths. Each of the four PDs 19 receives the four-channel optical output signals output from the optical demultiplexer 21 and converts those optical signals into photocurrents. The TIA 23 converts each of the four photocurrents output from the four-channel PD 19 into an electric signal RX. This TIA 23 is connected in common to the four PDs 19 and integrated in the ROSA 11 for the miniaturization of the optical transceiver 1 and processes the photocurrent for four channels. Further, the TIA 23 has an on / off function of the electrical signal RX for each channel, a function of turning off the electrical signal RX of the channel when a LOS occurs in each channel, and a LOS described later, as the function of the optical transceiver 1 increases. A function to refer to abnormal information at the time of occurrence is included. The CDR circuit unit 5 receives the 4-channel electrical signal RX from the ROSA 11 and shapes the waveform, thereby outputting a 4-channel electrical signal RX having a data transfer rate of, for example, 10 Gbps or 25 Gbps to the outside.

  Although the CDR circuit units 3 and 5 and the LDD circuit unit 7 have functions for four channels, they may be configured by separate circuit units for each channel. Also, the CDR circuit units 3 and 5 may be integrated or provided outside the optical transceiver 1. Further, the CDR circuit unit 3 may have a function of synthesizing / separating 10 electric signals with a data transfer rate of 10 Gbps, for example, into 4 electric signals with a data transfer rate of 25 Gbps, for example. The CDR circuit unit 5 may have a function of synthesizing and separating, for example, four electric signals with a data transfer rate of 25 Gbps into ten electric signals with a data transfer rate of 10 Gbps, for example.

  Further, the ROSA 11 has a function as a detection circuit unit that constantly detects an input signal disconnection (LOS) every four channels of the optical transceiver 1 and stores the detection result in a register in the TIA 23 that functions as a storage circuit unit. . That is, the ROSA 11 monitors the four-channel electrical signal RX generated by the TIA 23, detects an abnormality occurrence state for each of the four-channel electrical signal RX, and at the timing when the occurrence of LOS is detected in any channel. Abnormal information corresponding to the LOS occurrence state for each electrical signal RX of the channel is stored. For example, in the TIA 23, a flag bit (“0” or “1”) indicating whether or not LOS has occurred is stored in the register address provided for each channel as abnormality information.

  The CPU 13 is a control circuit for performing overall control and monitoring of the optical transceiver 1. The CPU 13 is not limited to a one-chip microcomputer, and may include a plurality of CPUs, an FPGA (Field-Programmable Gate Array), a CPLD (Complex Programmable Logic Device), and the like.

The optical transceiver 1 is also provided with various signal lines for monitoring and control between internal circuit units and external devices. That is, the CPU 13 and the ROSA 11 are connected by a serial communication bus L ₁ such as I ² C and an alarm signal line L ₂ for transmitting a LOS signal (alarm signal) for notifying the occurrence of LOS. Here, the alarm signal line L ₂ is limited other power line, the presence of ground connection line such as wiring (not shown), and space saving, from the viewpoint of miniaturization, a minimum of one. Further, the CPU 13 and the LDD circuit unit 7 are connected by a signal transmission signal line L ₃ for instructing blocking of the optical signal of each channel under the control of the host device 50. Various alarm signals are transmitted between the CPU 13 and the external host device 50 from the control signal line L ₄ for controlling the optical transceiver 1, the serial communication bus L ₅ such as I ² C and MDIO, and the optical transceiver 1. alarm signal line L _{6 and,} for, are connected by the alarm signal line L ₇ for transmitting LOS signal (alarm signal) for notifying the occurrence of the LOS from the optical transceiver 1. FIG. 2 shows an extracted connection configuration between the CPU 13 and the ROSA 11. Thus, the number of signal lines between the CPU 13 and the ROSA 11 is reduced to two.

  Next, the operation at the time of LOS notification to the host device 50 when the LOS occurs in the optical transceiver 1 of the present embodiment will be described with reference to FIG. FIG. 3 is a sequence diagram showing the procedure of the LOS signal notification operation between the optical transceiver 1 and the host device 50.

First, when an event of LOS in any of the electrical signals RX of four channels in ROSA11 is detected, LOS signal is sent to the CPU13 via the alarm signal line _{L 2} (step S01). At the same time, in the ROSA 11, abnormality information indicating the LOS occurrence state for each of the four-channel electrical signals RX is stored in the register R0 in the TIA 23. For example, in the register R0, flag bits (“1” or “0”) indicating whether or not LOS has occurred are stored in addresses A1 to A4 corresponding to 1ch to 4ch.

On the other hand, when receiving the LOS signal from the ROSA 11, the CPU 13 detects an interrupt and operates to read the abnormality information from the TIA 23 in the TOSA 11 (step S02). At this time, the CPU 13 accesses the register of the TIA 23 via the serial communication bus L ₁ , reads flag bits indicating the presence or absence of LOS from the addresses A ₁ to A 4 in the register, and reads these flag bits in the CPU 13. Store in register. Note that this read operation and storage operation may be performed in units of 1 byte (8 bits) or 1 word (2 bytes or 4 bytes).

Immediately after completion of the operation in step S02, CPU 13 may, LOS signal to the host device 50, which via another alarm signal line _{L 7} is an alarm signal line _{L 2,} notifies the LOS occurrence in any channel Is transmitted (step S03). On the other hand, the host device 50 operates to read the abnormality information from the register in the CPU 13 (step S04). At this time, the host device 50 accesses the register of the CPU 13 via the serial communication bus L ₅ , reads flag bits indicating whether or not LOS corresponding to each channel has occurred, and stores these flag bits in the host device 50. Stored in the register R1. Note that this read operation and storage operation may be performed in units of 1 byte (8 bits) or 1 word (2 bytes or 4 bytes).

According to the notification operation of the optical transceiver 1 of the LOS signal, CPU 13, when via the serial communication bus L ₅ from the host device 50 LOS occurrence of each channel is requested, provide accurate information it can. However, according to the CFP standard, it is required to complete within 100 μsec from the occurrence of the LOS event to the notification of the LOS signal to the host device. When it takes about 50 μsec from the occurrence of the LOS event to the provision of the LOS signal from the TIA 23 to the CPU 13, if the communication speed of the serial communication bus L ₁ is 1 MHz, for example, it will be about 36 μsec. Information can be provided and requests within 100 μsec can be met. Conversely, the communication speed of the serial communication bus L ₁ is required to be somewhat faster than about 1 MHz.

According to the optical transceiver 1 described above, when an abnormality at least one of the electrical signals RX of four channels is detected in ROSA11 is, LOS signal is sent to the inside of CPU13 via the alarm signal line L ₂ At the same time, the abnormality information indicating the LOS occurrence state for each of the four-channel electrical signals RX is stored in a register in the TIA 23. Further, the CPU 13, the abnormality information is read out in advance from TIA23 in response to receiving the LOS signal over the serial communications bus _{L 1.} As a result, after the LOS signal is sent to the host device 50, the host device 50 can immediately read out the abnormality information corresponding to the LOS occurrence state from the CPU 13 to reduce the size of the device such as the ROSA 11. Even when the TIA is shared and the alarm signal lines are reduced, the LOS signal notification to the host device 50 can be efficiently executed within a predetermined time. As a result, it is possible to ensure the consistency of LOS signal notification and execute processing at high speed.

Further, when the CPU 13 receives the LOS signal from the ROSA 11, after reading the abnormality information from the TIA 23 via the serial communication bus L ₁ , the CPU 13 notifies the host device 50 via the alarm signal line L ₇ . Thus, in response to the detailed LOS information read request from the host device 50 immediately after the LOS signal is sent, the CPU 13 can return appropriate detailed information corresponding to the LOS occurrence state at that time.

Here, the effect in this embodiment is further demonstrated, comparing with a comparative example. FIG. 8 is a block diagram illustrating a schematic configuration of an optical transceiver 801 according to a comparative example. The optical transceiver 801 shown in the figure is different from the optical transceiver 1 of this embodiment in that a TIA is not built in the ROSA 811 and a TIA 823 is provided as an individual circuit unit. From the TIA 823 to the CPU 813 Four alarm signal lines L ₂ for notifying the occurrence of LOS for each channel are provided, and an alarm signal line L ₇ for transmitting a LOS signal from the TIA 823 to the host device 50 is provided from the alarm signal line L _2. The branching point is connected to the host device 50. In the optical transceiver 801 having such a configuration, LOS event occurrence for each channel is detected by TIA823, notifies the CPU813 LOS signal indicative of the LOS occurrence for each channel via the four alarm signal lines _{L 2} Is done. At the same time, (or it may be provided via CPU813) is provided directly to the host device 50 via an alarm signal line _{L 7} LOS signal from TIA823 showing the LOS occurrence in either channel. Thereafter, the host device 50 requests detailed LOS information from the CPU 813 via the serial communication bus L ₅ in order to specify which channel the LOS has occurred in. However, the CPU 813 has already received the LOS for each channel. Detailed LOS information can be provided immediately because the signal is acquired. However, the configuration of the optical transceiver 801 is difficult to reduce in size because the TIA 823 is a separate circuit different from the ROSA 811 and it is necessary to secure a space for installing an alarm signal line.

FIG. 9 is a block diagram showing an extracted configuration of the optical receiving device in an optical transceiver according to another modification. In this modification, four ROSAs 911a, 911b, 911c, and 911d are provided for each channel, and the optical demultiplexer 921 is provided as a component housed in a separate package from the ROSA, and each ROSA 911a, 911b, 911c, PD 919a, 919b, 919c, 919d and TIA 923a, 923b, 923c, 923d are built in 911d. Each ROSA911a, 911b, 911c, an alarm signal line _{L 2} for notifying the LOS occurrence for each channel CPU913 from 911d is provided this 4. In such a modification, LOS signal for each channel is notified to the CPU913 through the four alarm signal line L _2. Immediately thereafter, LOS signal indicative of the LOS occurrence in either channel is provided to the host device 50 via an alarm signal line _{L 7} from CPU 913. Thereafter, the host device 50, but would require a detailed LOS information via the serial communication bus _{L 5} to CPU 913, CPU 913 can provide detailed LOS information immediately. However, the configuration of this comparative example is a component in which the optical demultiplexer 921 is housed in a separate package from the ROSA, and the ROSA has a 4-channel individual configuration, so that a space for installing an alarm signal line is secured. However, it is difficult to reduce the size.

  In addition, the optical transceiver 1 may be operated in the procedure shown in FIG. 10 instead of the LOS notification operation shown in FIG. That is, in FIG. 10, when the ROSA 11 detects an LOS event in any channel, the LOS signal is sent to the CPU 13 (step S901), and immediately after that, the CPU 13 notifies the host device 50 of the LOS signal (step S901). S902). After that, the CPU 13 reads the abnormality information indicating the LOS occurrence state for every four channels from the register R0 of the TIA 23, and stores the abnormality information in a register in the CPU 13 (step S904). In response to this, the host device 50 receives the notification of the LOS signal (step S902) and operates to read out the abnormality information from the register in the CPU 13 (steps S903 and 905). It may occur before the latest abnormality information is reflected on the internal register. For example, there is a case where detailed LOS information indicating that LOS has not occurred in all channels is provided even though LOS has occurred in any channel. Therefore, the operation procedure shown in FIG. 10 provides inaccurate detailed LOS information that does not reflect the current LOS occurrence status.

  Compared to these comparative examples, the optical transceiver 1 of the present embodiment is easy to miniaturize because the TIA 23 is built in the TOSA 11 and the number of alarm signal lines is reduced. In addition, even if the number of alarm signal lines is reduced, appropriate detailed information corresponding to the LOS occurrence state at that time can be quickly returned in response to a read request from the host device 50.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The configuration of the optical transceiver in this embodiment is the same as that of the optical transceiver 1 according to the first embodiment. FIG. 4 shows the procedure of the LOS notification operation to the host device 50 when the LOS occurs in the optical transceiver 1 of this embodiment. FIG. 5A shows the LOS transmitted from the ROSA 11 to the CPU 13 during the LOS notification operation. FIG. 5B shows a time waveform of the LOS signal transmitted from the CPU 13 to the host device 50 during the LOS notification operation.

First, when an LOS event is detected in any one of the four-channel electrical signals RX in the ROSA 11, abnormality information indicating the LOS occurrence state for each of the four-channel electrical signals RX is stored in the register R0 in the TIA 23. . At the same time, the ROSA 11 specifies the LOS occurrence state for each of the four-channel electrical signals RX based on the abnormality information stored in the register R0 in the TIA 23. Immediately thereafter, ROSA11 generates a pulse signal having a waveform indicating the LOS occurrence of each electrical signal RX of the four-channel, and sends the pulse signal to the CPU13 via the alarm signal line _{L 2} as LOS signal (step S11 ).

At this time, the LOS signal generated by the ROSA 11 is set to a waveform as shown in FIG. This LOS signal rises from a low level to a high level in synchronization with the detection timing T ₁ of LOS generation, and immediately after the rising timing T ₁ , a rectangular pulse having the number of pulses corresponding to the LOS generation state for each of the four-channel electrical signals RX. having a waveform as the pulse P ₁ is repeated.

Returning to FIG. 4, in response to the operation of step S < _b > 11, the CPU 13 starts taking in the LOS signal via the alarm signal line L < _b > ₂ and accepts external interrupts of other signals via the alarm signal line L < _b > _2. Is prohibited. Thus, CPU 13 is the default processing for the external interrupt to be performed during normal, so as not to perform duplicate to repetitive rectangular pulse P _1. The CPU 13 captures the LOS signal and counts the number of pulses after the rising timing for a predetermined time after the acceptance of the external interrupt is prohibited. Next, the CPU 13 identifies combinations of LOS occurrence states for each channel based on the counted number of pulses, and stores abnormality information corresponding to these combinations in a register in the CPU 13. Immediately thereafter, CPU 13, to the host device 50, via another alarm signal line _{L 7} is an alarm signal line _{L 2,} and sends a LOS signal notifying the LOS occurrence of either channel (step S12). Thereafter, the CPU 13 operates to allow acceptance of external interrupts for other signals. At this time, LOS signal generated by the CPU 13, as shown in FIG. 5 (b), is set to a waveform as rises from the low level to the high level in accordance with the detection timing _{T 2} of the LOS generation in CPU 13.

In contrast, the host device 50 is operative to read out the abnormality information through the serial communication bus _{L 5} from the register in the CPU 13 (step S13). At this time, the host device 50 stores the read abnormality information in the register R1 in the host device 50.

Figure 6 shows the number of pulses of the rectangular pulse P ₁ in the LOS signal set by the ROSA11 the present embodiment, the correspondence between the LOS occurrence state of each channel. In this way, the number of pulses is set to 0 to 15 for 16 combinations of LOS occurrence states of 4 channels. For example, for the combination of all “0 (none)” LOS occurrence states of channels “1” to “4”, the number of pulses is set to “0”, and the LOS occurrence states of channels “1” to “4” Are all set to “15” for a combination of “1 (present)”. Here, the correspondence of the number of pulses to the combination of the LOS generation states of each channel in FIG. 6 is an example, the correspondence of the number of pulses may be reversed, or the number of pulses for the combination of the LOS generation states having a high occurrence probability is small. It may be made to become. In addition, a function for setting the number of pulses of the LOS signal may be implemented in the TIA 23 itself in the ROSA 11. Further, in such a case, the correspondence is changed so that at least one pulse is output even for a combination of all “0”, and when the number of pulses counted by the CPU 13 is zero, the CPU 13 However, a malfunction or failure of the circuit may be detected.

FIG. 7 is a flowchart showing the procedure of the LOS notification operation in the CPU 13 of this embodiment. CPU13, when detecting a rise of the LOS signal receives the LOS signal from ROSA11, starts LOS notification operation, prohibits acceptance of external interrupt via the subsequent alarm signal line _{L 2} (step S21). Next, the CPU 13 starts capturing the LOS signal from the rising timing of the LOS signal (step S22), and starts timer interruption for a predetermined time (for example, 33 μsec) (step S23). Then, CPU 13 at the timing when the timer interrupt has passed a predetermined completion time, by taking the number of rectangular pulses P ₁ captured from the rising timing of LOS signal, identifies the combination of LOS occurrence status of each channel ( Step S24). At the same time, the CPU 13 writes the abnormality information indicating the combination of the LOS occurrence states of the respective channels to the internal register. Then, CPU 13 may sends out an LOS signal to the host device 50 via the alarm signal line _{L 7} (step S25), and permits the reception of the external interrupt subsequent other signal via the alarm signal line _{L 2} (Step S26). Thus, CPU 13, upon receiving the external interrupt from ROSA11, the maximum in the time required to receive the rectangular pulse _{P 1} number of pulses corresponding to a combination of LOS occurrence of all channels from ROSA11 external interrupt The acceptance of is prohibited. For example, when the time width of the rectangular pulse P ₁ set to the LOS signal is set to 2 μsec and a maximum of 15 rectangular pulses P ₁ are set to the LOS signal, the set interval of the rectangular pulse P ₁ in the LOS signal The maximum length is 30 μsec. In such a case, the CPU 13 sets a 33 μsec timer after detecting the rise of the LOS signal, and does not accept an external interrupt within that time.

According to the second embodiment described above, when an abnormality is detected in any of the electrical signals RX of four channels in ROSA11 is the CPU13 via the alarm signal line L _2, 4 channels per electrical signal RX A LOS signal having a waveform corresponding to the LOS occurrence state is sent out. Further, the CPU 13 specifies in advance an abnormality occurrence state for each of the four-channel electrical signals RX according to reception of the LOS signal. As a result, after the LOS signal is sent from the CPU 13 to the host device 50, the host device 50 can immediately read detailed LOS information corresponding to the abnormal state at that time from the CPU 13, and the device is downsized. Even so, the LOS occurrence notification to the host device 50 can be efficiently executed within a predetermined time. As a result, it is possible to ensure the consistency of LOS signal notification and execute processing at high speed.

For example, the time width of the rectangular pulse P ₁ set in the LOS signal is set to 2 μsec, and the CPU 13 sets a 33 μsec timer after detecting the rise of the LOS signal, and counts the number of pulses of the LOS signal during that time. Shall. If, LOS is generated in all channels, up to 15 square pulses P ₁ is the case where it is set to LOS signal, the length of the set interval of the rectangular pulse P ₁ in the LOS signal is 30 .mu.sec. At this time, even when the time from the occurrence of the LOS event in the TIA 23 to the time when the LOS is detected is 50 μsec, it is possible to meet the request that the LOS signal issuance to the host device 50 is within 100 μsec.

  Here, since the ROSA 11 sets the number of pulses of the LOS signal corresponding to the combination of the LOS generation states of a plurality of channels, the detailed LOS generation state can be specified appropriately from the waveform of the LOS signal received by the CPU 13. .

Further, CPU 13, upon receiving an external interrupt via an alarm signal line L _2, at least, within the time required to receive the rectangular pulse P ₁ of a predetermined number so prohibits acceptance of external interrupt, CPU 13 However, it is possible to prevent interruption of other processing when the LOS signal is received, and to correctly notify the host device 50 of occurrence of LOS.

  The preferred embodiments according to the present invention have been illustrated and described above, but the present invention is not limited to the specific embodiments described above. That is, it is easily recognized by those skilled in the art that various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

1 ... optical transceiver, 11 ... ROSA (light receiving device), 13 ... CPU (microcomputer), 21 ... optical demultiplexer, 23 ... TIA (storage circuit section, detection circuit section), 50 ... host device, _{L 1} ... Serial communication bus, L ₂ ... alarm signal line, L ₇ ... (external) alarm signal line, O _in ... optical input signal, RX ... electric signal.

Claims (3)

An optical receiving device comprising: a demultiplexer that demultiplexes an optical input signal into a plurality of optical output signals having different wavelengths; and a detection circuit unit that detects an abnormality for each of the plurality of optical output signals.
A microcomputer connected to the optical receiving device via an alarm signal line,
The optical receiving device detects an abnormality occurrence state for each of the plurality of optical output signals based on abnormality information corresponding to the occurrence of the abnormality when detecting an abnormality in at least one of the plurality of optical output signals. Identify and send a pulse signal indicating the abnormality occurrence state for each of the plurality of optical output signals to the microcomputer via the alarm signal line;
The microcomputer is an optical transceiver that identifies the abnormality occurrence state for each of the plurality of optical output signals based on the pulse signal when receiving the pulse signal from the optical receiving device. It said light receiving device, wherein the abnormality is to set the number of pulses in said pulse signal in response to a combination of the plurality of optical output signals generated, claim 1 optical transceiver according. When the microcomputer receives an external interrupt via the alarm signal line, at least the pulse signal of the maximum number of pulses specified corresponding to the combination of the plurality of optical output signals from the optical receiving device The optical transceiver according to claim 2 , wherein reception of the external interrupt is prohibited within a time required to receive the signal.

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