JP2010130316A - Optical transmitter and update method of firmware - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmitter capable of updating firmware in a state that optical communication is maintained without being removed from a host device. <P>SOLUTION: The optical transmitter 1 is attached to the host device 2, and is provided with: an LD 11a; and a controller 13 which executes control by the firmware to control at least light emission intensity of the LD 11a to a predetermined value. The controller 13 has: an output value storage means 23 for storing an output value regarding control by the firmware in reception when a firmware rewrite signal is received from the host device 2; a fixed value control means 24 for stopping control by the firmware to control the output value to the stored output value while the recorded firmware is rewritten to new firmware to be transmitted from the host device 2; and a firmware control restart means 25 for starting control by the new firmware after the end of rewrite to the new firmware. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical transmission device applied to an optical transceiver and the like, and a method for updating firmware of the optical transmission device.

  An optical transmission device that transmits signal light for optical communication includes, for example, a semiconductor light emitting element (LD) 101 and an LD drive circuit 102 as shown in FIG. A DC bias current is generated so that a predetermined light emission power can be obtained from the LD 101, and a modulation current is generated based on a transmission signal received from the host device X. The optical transmission device 100 supplies the LD 101 with a current obtained by superimposing the modulation current on the DC bias current, thereby transitioning the light emission intensity of the LD 101 and modulating the LD signal light.

  In addition, the optical transmission apparatus 100 uses a digital controller 104 that supplies a bias current value and a modulation current value to the LD drive circuit 102 through a digital / analog conversion unit (D / A) 103, and performs auto power control (APC) of the LD 101. : Auto Power Control). Specifically, in the optical transmission device 100, a semiconductor light receiving element (PD: Photo Diode) 105 disposed in the vicinity of the LD 101 detects the light emission power of the LD 101, and a current value corresponding to the detected power is represented by the light amount detection circuit 106 and An analog / digital conversion unit (A / D) 107 performs digital conversion and inputs to the controller 104. Then, the controller 104 determines a bias current based on the digital value input from the A / D 107 and a pre-programmed function so that the detected light emission power is constant, and a control signal used to generate the bias current is determined. APC control is performed by inputting to the D / A 103.

In an optical transceiver to which such an optical transmitter is applied, in recent years, an operation parameter related to an operation state of the optical transceiver using a communication protocol such as I2C (Inter-Integrated Circuit) or MDIO (Management Data Input / Output) is used. Is generally transmitted to the host device (see, for example, Non-Patent Document 1).
In addition, a method of controlling a built-in component of an optical transmission device (optical transceiver) using a digital controller, such as the APC control described above, has a high affinity with a form using the communication protocol described above, and is widely used at present. It is starting to be used.

  In order to control the built-in components of the apparatus using a digital controller, an arithmetic unit such as the CPU 104a and firmware describing processing necessary for the control are required as in the controller 104 in the example of FIG. For example, the firmware is stored in a flash memory 104b built in the controller 104 (or stored in a storage device provided outside the controller 104) and loaded into the RAM 104c of the controller 104 at the time of activation.

Conventionally, in order to update the firmware, it is necessary to remove the optical transmission device from the host device once, temporarily stop optical communication, and use a dedicated tool. In recent years, in the field of optical transceivers, due to the spread of pluggable devices, removal from the host device has become easier, but it is still necessary to stop the network when updating the firmware, and measures are desired. ing.
SFF Committee, “SFF-8472 Specification for Diagnostic Monitoring Interface for Optical Xcvrs Rev 10.3”, [online], December 1, 2007 [Search on September 12, 2008], Internet <URL: ftp://ftp.seagate.com/sff/SFF-8472.PDF>

  The present invention has been made in view of the above circumstances, and an optical transmission device capable of updating firmware while maintaining optical communication without being removed from a host device, and the optical transmission device An object of the present invention is to provide a method for updating the firmware.

An optical transmission device of the present invention includes a semiconductor light emitting element that emits signal light, and a controller that has firmware and executes a control operation by the firmware, and controls at least the light emission intensity of the semiconductor light emitting element to a predetermined value. Is attached to the host device. When the control unit receives a firmware rewrite signal from the host device, an output value storage unit that stores an output value related to control by the firmware at the time of reception, and a new firmware transmitted from the host device of the recorded firmware During rewriting to the firmware, the control by the firmware is stopped, the fixed value control means for controlling the output value to the output value saved by the output value saving means, and the control by the new firmware after the rewriting to the new firmware is completed. Firmware control restarting means for starting.
During rewriting to the new firmware, it is preferable to provide a switch for switching the communication destination with the host from the control unit to the firmware storage unit.

  The method of updating the firmware of the optical transmission device according to the present invention includes a semiconductor light emitting element that emits signal light and firmware, and executes a control operation by the firmware, and controls at least the light emission intensity of the semiconductor light emitting element to a predetermined value. And a firmware update method for an optical transmission device attached to the host device. An output value that receives a firmware rewrite signal from the host device, saves an output value related to the control by the firmware by the output value storage means, and stops the control by the firmware and saves the output value of the control unit by the fixed value control means After starting the control to fix the output value, the recorded firmware is rewritten to the new firmware transmitted from the host device. After the rewriting is finished, the control for fixing the output value is stopped by the firmware control restarting means, and the new firmware is used. Control is started.

  According to the present invention, since the communication between the host device and the firmware storage unit is enabled, the firmware can be rewritten directly from the host device. In addition, while the processing according to the firmware is stopped for the update, the drive current value immediately before the stop is continuously supplied to the drive circuit, so the firmware update is performed while maintaining the optical communication. It can be performed.

  FIG. 1 is a block diagram illustrating a configuration example of an optical transmission apparatus according to the present invention. The optical transmission device is modularized as an optical data link or the like, and further used in a state of being connected to a host device. The optical transmission apparatus of the present invention is provided with differential input terminals 10a and 10b for receiving an electrical signal from the host apparatus 2, as exemplified by the optical data link 1 of FIG. Complementary differential input signals E + and E− are input to these terminals 10a and 10b, respectively.

  The optical data link 1 includes a transmission optical module 11, an LD drive circuit 12, a controller 13, a D / A 14, an A / D 15, a light amount detection circuit 16, and an EEPROM (Electrically Erasable and Programmable Read Only Memory) 17. And a switch 18.

  The transmission optical module 11 includes an LD 11a that transmits signal light and a PD 11b that monitors the LD 11a. The signal light from the LD 11 a is coupled to the optical connector 19 by an optical system (not shown), and is output to the optical fiber F through the optical connector 19. The PD 11 b receives light emitted from the LD 11 a (for example, part of the signal light), detects the light intensity, generates an output current signal corresponding to the intensity, and outputs the output current signal to the light amount detection circuit 16.

  The LD 11 a is connected to the LD drive circuit 12. The LD drive circuit 12 is a circuit that drives the LD 11a in accordance with an input signal to output light, and supplies a drive current (DC bias current and modulation current) to the LD 11a. The LD drive circuit 12 is connected to differential input terminals 10a and 10b, receives differential input signals E + and E− from these terminals 10a and 10b, and receives a modulation current modulated in accordance with the difference signal. Generate. Then, this modulation current is superimposed on the bias current and supplied to the LD 11a. As a result, the LD 11a is driven, and an optical signal modulated according to the modulation current is output from the LD 11a.

  The LD drive circuit 12 is connected to the controller 13 via the D / A 14. The controller 13 is a control unit that executes various processes including a process for generating a control signal for controlling the drive current and a process for supplying the control signal to the LD drive circuit 12. The controller 13 performs APC control during normal operation to stabilize the average value of the optical output of the LD 11a. In the APC control, the optical output of the LD 11a measured by the PD 11b is compared with a predetermined value, and the magnitudes of the bias current and the modulation current are adjusted according to the difference therebetween. Note that the optical data link controller of the present invention is characterized by processing in the operation at the time of firmware update, not in the processing in the normal operation described above. The characteristic processing will be described later.

  The controller 13 outputs a digital value (drive current control signal) corresponding to the magnitudes of the bias current and the modulation current to the D / A 14. The D / A 14 converts these digital values into analog signals and supplies them to the LD drive circuit 12. The LD drive circuit 12 adjusts the magnitudes of the bias current and the modulation current according to these analog signals.

Further, a light amount detection circuit 16 is connected to the controller 13 via an A / D 15.
The light quantity detection circuit 16 converts the output current signal of the PD 11b into a corresponding analog voltage signal. The A / D 15 converts the analog voltage signal into a digital value and sends it to the controller 13. The digital value corresponds to the output current signal of the PD 11b as described above, and thus indicates the light output detected by the PD 11b. Hereinafter, this digital value is referred to as an output monitor value.

  The controller 13 is connected to an EEPROM 17. The EEPROM 17 is a storage unit that stores firmware. The firmware in the optical data link 1 describes the process of the controller 13 in the normal operation including the control signal generation process (that is, the APC control process) for making the signal light of the LD 11a have a predetermined intensity, in other words, It includes an application program describing processing related to optical transmission operation such as LD control and monitor control. For example, the firmware is loaded in an executable form from the EEPROM 17 by the controller 13 when the optical data link 1 is activated and when the firmware rewrite is completed. That is, it is read from the EEPROM 17, developed in a RAM (Random Access Memory) 13 c of the controller 13 and executed.

  The controller 13 and the EEPROM 17 are connected via a switch 18 to a serial communication (port) terminal 20 for performing communication with the host device 2. During normal operation, the controller 13 receives a command from the host device 2 via the serial communication terminal 20 and, in response to the command, serializes data (for example, output monitor value) indicating the operation status of the optical data link 1. The data is output to the host device 2 through the communication terminal 20. On the other hand, when updating the firmware, the EEPROM 17 receives new firmware from the host device 2 via the serial communication terminal 20, and the old firmware is rewritten with the firmware. Note that communication between the optical data link 1 and the host device 2 via the serial communication terminal 20 is performed using a communication protocol such as I2C or MDIO.

  The switch 18 positioned between the serial communication terminal 20 and the controller 13 and the EEPROM 17 switches the connection destination of the terminal 20 to the controller 13 or the EEPROM 17. The switch 18 is connected to a rewrite signal terminal 21 which is an input terminal of a signal (rewrite signal) for notifying that the firmware is being rewritten, and switches the connection destination according to the state of the rewrite signal.

  The controller 13 connected to the above-described EEPROM 17, the switch 18 and the like has, for example, a CPU 13a as an arithmetic unit, and further stores a flash memory 13b for storing an update program describing processing of the controller 13 at the time of firmware update. Have In addition to the update program, the flash memory 13b stores a startup program that describes the processing of the controller 13 when the optical data link 1 is started. These basic programs such as the update program and the startup program are read from the flash memory 13b by the controller 13 as appropriate when the optical data link 1 is started, and are expanded and executed in the RAM 13c of the controller 13.

The RAM 13c is composed of an area for temporarily storing various data, is used as a development area for update programs and firmware, and further stores data used when executing the processing described in the update program and firmware. It is also used as a data area.
The controller 13 configured as described above functions as an update control device 13d described later by executing an update program on the CPU 13a.

Further, the rewrite signal terminal 21 connected to the switch 18 as described above is connected to the controller 13.
The rewrite signal terminal 21 is used when the host device inputs a rewrite signal to the controller 13 or the switch 18 during rewriting of the firmware. The rewrite signal is input (asserted) only during a period when the firmware is being rewritten, and the input is canceled (deasserted) during the normal operation of the optical data link 1.

The operations of the switch 18 and the controller 13 before and after the input and release of the rewrite signal include an operation for firmware update, which is a characteristic operation in the present invention, as will be described below with reference to FIG.
The switch 18 sets the connection destination of the serial communication terminal 20 to the controller 13 when the input of the rewrite signal is cancelled, and sets the connection destination of the serial communication terminal 20 to the EEPROM 17 when the rewrite signal is input. Firmware can be rewritten.

The controller 13 executes an update program for firmware update, and thereby has an update control apparatus having a signal input / input release detection means 22, an output value storage means 23, a fixed value control means 24, and a firmware control restart means 25. It functions as 13d.
The signal input / input release detection means 22 detects the input and release of the rewrite signal. The output value storage unit 23 stores an output value related to control by firmware at that time at a predetermined timing (for example, when the detection unit 22 detects the input of the rewrite signal (that is, when the rewrite signal is received)). . The fixed value control means 24 stops the control by the firmware while the firmware recorded in the EEPROM 17 is rewritten to the new firmware transmitted from the host device, and the output value storage means 23 stores the output value. Control to fix the saved output value. The firmware control restarting means 25 stops the control by the fixed value control means 24 when the signal input / input release detection means 22 detects the input release of the rewrite signal and the completion of rewriting to the new firmware is detected. Execute (start) control by firmware.

  When the input of the rewrite signal is cancelled, the controller 13 functioning in this way executes the APC control process described in the firmware based on the output monitor value from the A / D 15, and the serial communication terminal 20 When an instruction is received from the host device 2 via the host device 2, an output monitor value or the like is output to the host device 2 in response to the command.

  Further, when the rewrite signal is input, the controller 13 stores the output value related to the control by the firmware at that time, stops the control by the firmware, and fixes the output value to the stored value. More specifically, the APC control process described in the firmware is stopped, the drive current control signal immediately before the stop of the APC control process is continuously input to the D / A 14 (that is, the LD drive circuit 12), and the signal light is emitted from the LD 11a. To continue. When the input of the rewrite signal is canceled, the controller 13 reads the rewritten firmware from the EEPROM 17 and starts the APC control process described in the new firmware. Until the APC control process of the new firmware is started, the input of the control signal and the transmission of the signal light are continuously performed.

The firmware is updated by the operation of the switch 18 and the controller 13 as described above.
In the present optical data link 1, as described above, the firmware from the host device 2 can be rewritten, and while the APC control process is stopped for the firmware update, the drive current value immediately before the stop is set. Since the supply to the LD drive circuit 12 is continued, the firmware can be updated without being removed from the host device 2 and without bringing down optical communication.

Next, an example of a method for updating the firmware of the optical data link 1 of FIG. 1 will be described with reference to the flowchart of FIG.
When updating the firmware, as shown in the figure, the host device 2 first inputs a rewrite signal to the switch 18 and the controller 13 of the optical data link 1 via the rewrite signal terminal 21 (step S1).

The switch 18 to which the rewrite signal has been input switches the connection destination of the serial communication terminal 20 to the EEPROM 17 (step S2). And firmware rewriting is started (step S3).
In addition, the rewrite signal input to the switch 18 is also connected to the controller 13 as described above. The controller 13 follows the update program developed on the RAM 13c and after the rewrite signal is input, before the new firmware is deployed. Processing is executed (step S4). This new firmware pre-deployment process is a process for not stopping optical communication when the new firmware is read and deployed. The stop process of the APC control process according to the old firmware, the final control signal (D / A value) storage processing and fixed value control processing (open loop control processing) using the stored control signal as a fixed value. In other words, it includes processing performed as the output value storage means 23 and fixed value control means 24 of the update control device 13d.

  This new firmware development pre-processing is started immediately after the input of the rewrite signal, for example. In this case, the control signal in the optical data link 1 (that is, the drive current of the LD 11a) is fixed at that just before the rewrite signal is input. The The LD 11a maintains the optical signal quality under the condition that the ambient temperature is constant even if the bias current and the modulation current are fixed. It is unlikely that the ambient temperature rapidly changes within the time for updating the firmware (at most 10 seconds), and the optical signal quality sufficient for practical use is maintained even with the fixed value control processing.

  The host device 2 cancels the input of the rewrite signal after the writing of the new firmware to the EEPROM 17 is completed and the rewriting of the firmware is completed (step S5). After detecting the release of the rewrite signal, the controller 13 of the optical data link 1 reads the new firmware from the EEPROM 17 and develops it on the RAM 13c (step S6). After the development, the controller 13 starts the APC control process according to the new firmware using the saved final control signal (D / A value) before the stop of the APC control process as a start value (step S7). This completes the firmware update. Note that the processing in step S6 and step S7 is also described in the update program, and these processing are performed by the controller 13 as the firmware control restarting means 25 of the update control device 13d. When the update is completed, the connection destination of the serial communication terminal 20 is switched to the controller 13 by the switch 18 from which the input of the rewrite signal is released.

  In the above description, the example in which the optical transmission apparatus is applied to an optical data link having only a transmission function has been described. However, the optical transmission apparatus of the present invention can also be applied to an optical transceiver having both transmission and reception functions. it can.

It is a block diagram explaining the structural example of the optical transmitter of this invention. It is a block diagram for demonstrating the characteristic operation | movement of the optical transmitter of this invention. 3 is a flowchart for explaining an example of a firmware update method of the optical transmission device in FIG. 1. It is a block diagram explaining the structural example of the conventional optical transmitter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical data link, 2 ... Host apparatus, 10a, 10b ... Differential input terminal, 11 ... Optical module for transmission, 11a ... LD, 11b ... PD, 12 ... LD drive circuit, 13 ... Controller, 13a ... CPU, 13b ... Flash memory, 13c ... RAM, 13d ... Update control device, 14 ... D / A, 15 ... A / D, 16 ... Light quantity detection circuit, 17 ... EEPROM, 18 ... Switch, 19 ... Optical connector, 20 ... Serial communication Terminals 21... Rewrite signal terminals 22... Signal input / input release detection means 23... Output value storage means 24... Fixed value control means 25.

Claims (3)

A semiconductor light emitting element that emits signal light and a control unit that has firmware and executes a control operation by the firmware and controls at least the light emission intensity of the semiconductor light emitting element to a predetermined value, and is mounted on the host device An optical transmitter,
The controller is
When receiving a firmware rewrite signal from the host device, output value storage means for storing an output value related to control by the firmware at the time of reception;
Fixed value control means for controlling the output value to the output value stored by the output value storage means by stopping the control by the firmware during rewriting of the recorded firmware to the new firmware transmitted from the host device When,
An optical transmission device comprising: firmware control restarting means for starting control by the new firmware after rewriting to the new firmware.   The optical transmission device according to claim 1, further comprising a switch that switches a communication destination with the host from the control unit to the firmware storage unit during rewriting to the new firmware. A semiconductor light emitting element that emits signal light and a control unit that has firmware and executes a control operation by the firmware and controls at least the light emission intensity of the semiconductor light emitting element to a predetermined value, and is mounted on the host device A method for updating firmware of an optical transmission device, comprising:
Receiving a firmware rewrite signal from the host device, storing an output value related to control by the firmware by an output value storing means;
After starting the control by the fixed value control means to stop the control by the firmware and fix the output value of the control unit to the stored output value,
Rewrite the recorded firmware to the new firmware sent from the host device,
A firmware update method comprising: after completion of rewriting, firmware control restarting means stops control for fixing the output value and starts control by the new firmware.

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