Transporting data and auxiliary signals over an optical link

Abstract

A data transport system for transporting data and auxiliary signals over an optical link comprises a transmitter, a receiver and an optical link. The transmitter and receiver are coupled to a first end of the optical link. The optical link includes a number of optical channels. A controller is coupled to the transmitter and the receiver, and controls the transmitter and the receiver to operate in a first state when data are detected at an input of the transmitter. Data are transported via the data transport system in the first state. The controller controls the transmitter and the receiver to operate in a second state when the data are detected as absent at the input of the transmitter. Data are prevented from being transported via the data transport system in the second state.

What is claimed is: 
     
       1. A device comprising:
 a transmitter coupled to a first end of an optical link, wherein the optical link includes optical channels and wherein each of the optical channels is capable of being enabled such that modulated signals are transported or disabled such that no modulated signals are transported; 
 a receiver coupled to the first end of the optical link, wherein a data transport system comprises the transmitter, the receiver, and the optical link; and 
 a controller coupled to the transmitter and the receiver; wherein 
 the controller controls the transmitter and the receiver to operate in:
 a first state in which data are transmitted and received via modulated signals by enabling one or more of the optical channels; and 
 a second state in which one or more auxiliary signals are transmitted by selectively enabling and disabling two or more of the optical channels and in which one or more auxiliary signals are received by determining which ones of the optical channels have been enabled and which ones of the optical channels have been disabled; and 
 
 which auxiliary signal is being transmitted or received is determined by which of the two or more of the optical channels are enabled or disabled. 
 
     
     
       2. The device of  claim 1 , comprising a detector coupled between an input of the transmitter and the controller, wherein the detector measures a parameter of input signals present at the input and outputs a detector signal representative of the parameter. 
     
     
       3. The device of  claim 2 , wherein the first state comprises a state in which an output of the transmitter is enabled and an output of the receiver is enabled. 
     
     
       4. The device of  claim 3 , wherein the first state includes a sub-state that is an electrical idle state, wherein the controller detects the electrical idle state using the detector signal. 
     
     
       5. The device of  claim 4 , wherein the electrical idle state comprises a state in which an output of the transmitter is disabled, an output of the receiver is enabled, and internal squelches coupled to each receiver output channel are enabled, and the controller is monitoring for the data at the input of the transmitter. 
     
     
       6. The device of  claim 4 , wherein in response to detecting the electrical idle state the controller disables an output of the transmitter. 
     
     
       7. The device of  claim 6 , wherein the controller disables the output of the transmitter by toggling at least one bit of a driver control signal in violation of a driver control signal protocol, wherein an output of at least one driver of the transmitter is disabled, wherein no light is transmitted over the optical channel when the driver is disabled. 
     
     
       8. The device of  claim 4 , wherein in response to detecting the electrical idle state the controller enables at least one output of the receiver. 
     
     
       9. The device of  claim 4 , wherein in response to detecting the electrical idle state the receiver enables at least one internal squelch of at least one receiver channel. 
     
     
       10. The device of  claim 4 , wherein the controller disables an output of at least one driver of the transmitter when an absence of light is detected on at least one output channel of the optical link. 
     
     
       11. The device of  claim 3 , wherein the controller uses a write-ahead protocol to reduce a delay resulting from control of the transmitter. 
     
     
       12. The device of  claim 3 , wherein the auxiliary signals include status and control signals. 
     
     
       13. The device of  claim 12 , wherein outputs of the transmitter are selectively enabled and disabled as appropriate to transmit auxiliary signals. 
     
     
       14. The device of  claim 12 , wherein:
 a value or values of the one or more auxiliary signals defines an auxiliary signal configuration; and 
 the controller controls the transmitter and the receiver to operate in the first state when a first auxiliary signal configuration is detected. 
 
     
     
       15. The device of  claim 14 , wherein the controller controls the transmitter and the receiver to operate in the second state when a second auxiliary signal configuration is detected. 
     
     
       16. The device of  claim 15 , wherein the first auxiliary signal configuration includes a first code that indicates that the transmitter and the receiver are properly configured to transmit the data. 
     
     
       17. The device of  claim 16 , wherein the second auxiliary signal configuration includes a second code that indicates that the transmitter and the receiver are improperly configured to transmit the data. 
     
     
       18. The device of  claim 17 , wherein the transmitter comprises a plurality of channels and a plurality of drivers corresponding to the plurality of channels, wherein the controller selectively enables and disables the plurality of drivers to generate the first code and the second code. 
     
     
       19. The device of  claim 2 , wherein the transmitter comprises a plurality of channels, wherein each channel includes a driver. 
     
     
       20. The device of  claim 19 , wherein the detector is coupled between an input of at least one channel and the controller, wherein the detector measures a parameter of input signals present at the input and outputs a detector signal representative of the parameter, wherein the controller compares the detector signal to a reference and uses the result of the comparison to determine when the data is present at the input of the transmitter. 
     
     
       21. The device of  claim 20 , comprising a driver control signal coupled between the controller and the driver, wherein the controller via the driver control signal enables a driver output of the driver when the data is detected at the input of the transmitter. 
     
     
       22. The device of  claim 21 , wherein the controller, when the driver output is disabled, writes ahead an initial portion of the driver control signal, and writes a final portion of the driver control signal when the data is detected at the input of the transmitter. 
     
     
       23. The device of  claim 21 , wherein the controller via the driver control signal disables the driver output when the data is detected as absent at the input of the transmitter. 
     
     
       24. The device of  claim 23 , wherein the controller disables the driver outputs of the transmitter when the controller detects at the receiver an absence of light received over the optical link. 
     
     
       25. The device of  claim 23 , wherein the controller disables the driver output by toggling at least one bit of the driver control signal in violation of a driver control signal protocol, wherein no light is transmitted over the optical channel when the driver output is disabled. 
     
     
       26. The device of  claim 1 , wherein the auxiliary signals include status and control signals, wherein the transmitter comprises at least one light-emitting device for transmitting the data over the optical link, wherein the receiver comprises at least one light-detecting device for receiving optical signals over the optical link. 
     
     
       27. The device of  claim 26 , wherein the transmitter operating in the first state converts first data signals to first optical signals and outputs the first optical signals to the optical link. 
     
     
       28. The device of  claim 27 , wherein the receiver operating in the first state converts second optical signals received over the optical link to second data signals. 
     
     
       29. The device of  claim 28 , wherein the transmitter operating in the second state converts first auxiliary electrical signals to first auxiliary optical signals and outputs the first auxiliary optical signals to the optical link. 
     
     
       30. The device of  claim 29 , wherein the receiver operating in the second state converts second auxiliary optical signals received over the optical link to second auxiliary electrical signals. 
     
     
       31. The device of  claim 26 , wherein the data comprises first data signals and second data signals, and wherein the auxiliary signals comprise first auxiliary signals and second auxiliary signals. 
     
     
       32. The device of  claim 31 , wherein the data and the auxiliary signals are compatible with a Peripheral Component Interconnect (PCI) Express (PCIe) protocol. 
     
     
       33. The device of  claim 31 , wherein the transmitter operates in the first state to transmit the first data signals over the optical link and operates in the second state to transmit the first auxiliary signals over the optical link. 
     
     
       34. The device of  claim 33 , wherein the receiver operates in the first state to receive the second data signals over the optical link and operates in the second state to receive the second auxiliary signals over the optical link. 
     
     
       35. The device of  claim 34 , wherein:
 a value or values of the one or more auxiliary signals defines an auxiliary signal configuration; and 
 the controller controls the transmitter and the receiver to operate in the first state when a first auxiliary signal configuration is detected, and controls the transmitter and the receiver to operate in the second state when a second auxiliary signal configuration is detected. 
 
     
     
       36. The device of  claim 35 , wherein the first auxiliary signal configuration includes at least one first code that indicates that the transmitter and the receiver are properly configured to transmit the data. 
     
     
       37. The device of  claim 36 , wherein the second auxiliary signal configuration includes at least one second code that indicates that the transmitter and the receiver are improperly configured to transmit the data. 
     
     
       38. The device of  claim 37 , wherein the transmitter comprises a plurality of channels and a plurality of drivers corresponding to the plurality of channels, wherein the controller selectively enables and disables driver outputs of the plurality of drivers to generate the at least one first code and the at least one second code. 
     
     
       39. The device of  claim 38 , wherein the at least one first code is a member of a first code set, wherein the first code set includes a first plurality of binary codes. 
     
     
       40. The device of  claim 39 , wherein the first plurality of binary codes comprises at least one of 0000, 0001, 0011, 1000, 1100, and 1111. 
     
     
       41. The device of  claim 38 , wherein the at least one second code is a member of a second code set, wherein the second code set includes a second plurality of binary codes. 
     
     
       42. The device of  claim 41 , wherein the second plurality of binary codes comprises at least one of 1001, 1011, 1101, and 1110. 
     
     
       43. The device of  claim 42 , wherein the second plurality of binary codes further comprises at least one of 0111, 0110, 0010, 0100, 0101, and 1010. 
     
     
       44. The device of  claim 42 , wherein the auxiliary signals are auxiliary signals of a PCIe protocol, and the second plurality of binary codes corresponds to at least one auxiliary signal. 
     
     
       45. The device of  claim 44 , wherein the binary code 1001 corresponds to a platform reset signal in a low logic state and a power on signal in a low logic state. 
     
     
       46. The device of  claim 44 , wherein the binary code 1011 corresponds to a platform reset signal in a low logic state and a power on signal in a high logic state. 
     
     
       47. The device of  claim 44 , wherein the binary code 1101 corresponds to a platform reset signal in a high logic state and a power on signal in a low logic state. 
     
     
       48. The device of  claim 44 , wherein the binary code 1110 corresponds to a platform reset signal in a high logic state and a power on signal in a high logic state. 
     
     
       49. The device of  claim 44 , wherein the binary code 1001 corresponds to a present signal in a low logic state and a wake signal in a low logic state. 
     
     
       50. The device of  claim 44 , wherein the binary code 1011 corresponds to a present signal in a low logic state and a wake signal in a high logic state. 
     
     
       51. The device of  claim 44 , wherein the binary code 1101 corresponds to a present signal in a high logic state and a wake signal in a low logic state. 
     
     
       52. The device of  claim 44 , wherein the binary code 1110 corresponds to a present signal in a high logic state and a wake signal in a high logic state. 
     
     
       53. The device of  claim 35 , wherein the auxiliary signals are auxiliary signals of a PCIe protocol. 
     
     
       54. The device of  claim 53 , wherein the auxiliary signals include at least one of a present signal, a wake signal, a platform reset signal, and a power on signal. 
     
     
       55. The device of  claim 54 , wherein the present signal is transmitted by a device to indicate the device is present on the optical link, wherein the wake signal is transmitted by a device to command a receiving device to awaken, wherein the platform reset signal is transmitted by a device to indicate a power state and a reset state of the device, wherein the power on signal is transmitted by a host to notify a target that host power is present. 
     
     
       56. The device of  claim 54 , wherein the first auxiliary signals comprise the present signal and the wake signal, and the second auxiliary signals comprise the platform reset signal and the power on signal. 
     
     
       57. The device of  claim 54 , wherein the first auxiliary signals comprise the platform reset signal and the power on signal, and the second auxiliary signals comprise the present signal and the wake signal. 
     
     
       58. The device of  claim 26 , wherein the transmitter comprises a plurality of channels and a plurality of drivers, wherein each channel includes a driver, and comprising a detector coupled between an input of at least one driver and the controller, wherein the detector measures a parameter of input signals present at the input and outputs a detector signal representative of the parameter. 
     
     
       59. The device of  claim 58 , wherein the controller compares the detector signal to a reference and uses the result of the comparison to determine when data is present at the input of the at least one driver. 
     
     
       60. The device of  claim 59 , comprising a driver control signal coupled between the controller and the at least one driver, wherein the controller via the driver control signal enables at least one driver output of the at least one driver when the data is detected at the input of the at least one driver. 
     
     
       61. The device of  claim 60 , wherein the driver control signal is coupled between the controller and a plurality of drivers of the transmitter, wherein the controller via the driver control signal enables a plurality of driver outputs of the plurality of drivers when the data is detected at the input of the at least one driver. 
     
     
       62. The device of  claim 60 , wherein the controller, when the at least one driver output is disabled, writes ahead an initial portion of the driver control signal, and writes a final portion of the driver control signal when the data signal is detected at the input of the transmitter. 
     
     
       63. The device of  claim 60 , wherein the controller via the driver control signal disables the at least one driver output when the data is detected as absent at the input of the at least one driver. 
     
     
       64. The device of  claim 63 , wherein the controller disables the at least one driver output when the controller detects at the receiver an absence of light received over the optical link. 
     
     
       65. The device of  claim 63 , wherein the controller disables the at least one driver output by toggling at least one bit of the driver control signal in violation of a driver control signal protocol, wherein no light is transmitted over the optical channel when the at least one driver output is disabled. 
     
     
       66. The device of  claim 60 , wherein the controller via the driver control signal disables a plurality of driver outputs of the transmitter when the data is detected as absent at the input of the at least one driver. 
     
     
       67. The device of  claim 26 , wherein outputs of the transmitter are selectively enabled and disabled as appropriate to transmit auxiliary signals. 
     
     
       68. The device of  claim 26 , wherein the first state comprises a plurality of sub-states. 
     
     
       69. The device of  claim 68 , wherein:
 a value or values of the one or more auxiliary signals defines an auxiliary signal configuration; and 
 a first sub-state is a data-idle state in which the first auxiliary signal configuration is detected, and data signals are absent at an input of the transmitter, wherein no data is transported over the optical link during the data-idle state. 
 
     
     
       70. The device of  claim 69 , wherein the data-idle state comprises a state in which an output of the transmitter is disabled, an output of the receiver is enabled, internal squelches coupled to each receiver output channel are enabled, and the controller is monitoring for the data at the input of the transmitter. 
     
     
       71. The device of  claim 69 , wherein a second sub-state is a data-active state in which the first auxiliary signal configuration is detected, and data signals are detected at an input of the transmitter, wherein data is transported optically over the optical link during the data-active state. 
     
     
       72. The device of  claim 71 , wherein the data-active state comprises a state in which an output of the transmitter is enabled and an output of the receiver is enabled. 
     
     
       73. A method for controlling a transmitter and a receiver in a device including:
 the transmitter coupled to a first end of an optical link that includes optical channels, wherein each of the optical channels is capable of being enabled such that modulated signals are transported or disabled such that no modulated signals are transported; 
 the receiver coupled to the first end of the optical link; and 
 a controller coupled to the transmitter and the receiver, the method comprising controlling the transmitter and the receiver to operate in:
 a first state in which data are transmitted via modulated signals by enabling one or more of the optical channels; and 
 a second state in which one or more auxiliary signals are transmitted by selectively enabling and disabling two or more of the optical channels and are received by determining which ones of the optical channels have been enabled and which ones of the optical channels have been disabled; and 
 
 which auxiliary signal is being transmitted or received is determined by which of the two or more of the optical channels are enabled or disabled. 
 
     
     
       74. A data transport system comprising:
 a transmitter coupled to an optical link comprising optical channels, wherein the transmitter operates in a first state to transmit first data signals over the optical link and operates in a second state to transmit one or more first auxiliary signals over the optical link; 
 a receiver coupled to the optical link, wherein the receiver operates in the first state to receive second data signals over the optical link and operates in the second state to receive one or more second auxiliary signals over the optical link; 
 a controller coupled to the transmitter and the receiver; wherein 
 the controller controls the transmitter and the receiver to:
 in the first state, transmit the first data signals and receive the second data signals by modulated signals over the optical link; and 
 in the second state, transmit the one or more first auxiliary signals by selectively enabling and disabling two or more of the optical channels and receive the one or more second auxiliary signals by determining which ones of the optical channels have been enabled and which ones of the optical channels have been disabled; and 
 
 which auxiliary signal is being transmitted or received is determined by which of the two or more of the optical channels are enabled or disabled. 
 
     
     
       75. A data transport system comprising:
 a transmitter and a receiver coupled to a first end of an optical link, wherein the optical link includes optical channels capable of being enabled such that modulated signals are transported or disabled such that no modulated signals are transported; and 
 a controller coupled to the transmitter and the receiver; wherein 
 the controller controls the transmitter and the receiver to operate:
 in a first state in which data are transmitted via modulated signals by enabling one or more of the optical channels; and 
 in a second state in which one or more auxiliary signals are transmitted by selectively enabling and disabling two or more of the optical channels and in which one or more auxiliary signals are received by determining which ones of the optical channels have been enabled and which ones of the optical channels have been disabled; and 
 
 which auxiliary signal is being transmitted or received is determined by which of the optical channels are enabled or disabled.