Asynchronous ID generation

Abstract

A technique for automatically establishing device IDs for devices in a daisy chain cascade arrangement. For each device, a write ID operation is initiated at the device to cause the device to enter a generate/write ID mode. While in this mode, a first value is input to the device. The device generates a second value from the first value. The device outputs the generated second value from the device to a next device in the daisy chain cascade which uses the second value as a first value for the next device. The device then establishes its ID from the first value. The process is repeated for all devices in the daisy chain cascade arrangement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention.

FIG. 1 is a high-level block diagram of a plurality of devices coupled in a daisy chain cascade arrangement that may be used with the techniques described herein.

FIG. 2 is a timing diagram illustrating the establishment of identifiers (IDs) for devices coupled in a daisy chain cascade arrangement.

FIGS. 3A-B are high-level block diagrams of a daisy chain cascade arrangement comprising dual port devices and a daisy chain cascade arrangement comprising single port devices, respectively, that may be used with the techniques described herein.

FIG. 4 is a block diagram of exemplary circuitry that may be used to establish IDs for single port devices in accordance with the techniques described herein.

FIG. 5 is a block diagram of exemplary circuitry that may be used to establish IDs for dual port devices in accordance with the techniques described herein.

FIG. 6 is a high-level block diagram of a daisy chain cascade arrangement of single port devices illustrating a state of the devices' IDs at a reset state.

FIG. 7 is a timing diagram illustrating timing involved with establishing the device IDs of devices during a power-up sequence.

FIGS. 8A-C are diagrams illustrating the establishment of IDs for devices using a control signal input to the devices to control the ID establishment process.

FIG. 9 is a block diagram of exemplary circuitry that controls the operation of the generation/write ID mode for a device using a control signal that is input to the device.

FIG. 10 is a flow chart of a sequence of steps that may be used to establish IDs for devices in a daisy chain cascade in accordance with the techniques described herein.

Claims

1. A method of establishing an identifier (ID) for a device configured in a daisy chain cascade arrangement having a plurality of devices, the method comprising: inputting a first value to a first device in the daisy chain cascade;outputting a second value generated from the first value from the first device to a second device in the daisy chain cascade via one or more outputs of the first device; andestablishing an ID for the first device from the first value.

2. A method as defined in claim 1 wherein inputting a first value to a first device includes acquiring the state of inputs of the first device.

3. A method as defined in claim 1 wherein establishing an ID for the first device includes placing the first value in storage associated with the first device.

4. A method as defined in claim 3 wherein the storage is a device ID register for the first device.

5. A method as defined in claim 1 wherein the ID is established in response to a command input into the first device.

6. A method as defined in claim 1 wherein the ID is established in response to a control signal that is asserted at an input of the first device.

7. A method as defined in claim 1 further comprising: adding a predetermined value to the first value to generate the second value.

8. A device configured in a daisy chain cascade arrangement having a plurality of devices, the device comprising: input circuitry configured to input a first value into the device;output circuitry configured to output a second value generated from the first value to a second device in the daisy chain cascade via one or more outputs of the device; andcircuitry configured to establish an identifier (ID) for the device from the first value.

9. A device as defined in claim 8 wherein the input circuitry configured to input the first value further comprises circuitry configured to acquire the state of inputs of the first device.

10. A device as defined in claim 8 wherein the circuitry configured to establish the ID for the device further comprises storage and circuitry configured to establish the ID for the device by placing the acquired state in the storage.

11. A device as defined in claim 8 further comprising: adder circuitry configured to add a third value to the first value to generate the second value.

12. A device as defined in claim 11 wherein the third value is a predetermined value.

13. A device as defined in claim 8 wherein the output circuitry includes: one or more output buffers configured to output the value to the second device in the daisy chain cascade.

14. A device as defined in claim 8 wherein the second value is generated in response to inputting a command into an input of the first device.

15. A device as defined in claim 8 wherein the value is generated in response to inputting a control signal into an input of the first device.

16. An apparatus for establishing an identifier (ID) for a device configured in a daisy chain cascade arrangement having a plurality of devices, the apparatus comprising: means for inputting a first value to a first device in the daisy chain cascade;means for outputting a second value generated from the first value from the first device to a second device in the daisy chain cascade via one or more outputs of the first device; andmeans for establishing an ID for the first device from the first value.

17. An apparatus as defined in claim 16 wherein the means for inputting a first value to a first device includes means for acquiring the state of inputs of the first device.

18. An apparatus as defined in claim 16 wherein the means establishing an ID for the first device includes means for placing the first value in storage associated with the first device.

19. An apparatus as defined in claim 16 wherein the ID is established in response to a command input into the first device.

20. An apparatus as defined in claim 16 wherein the ID is established in response to a control signal that is asserted at an input of the first device.

21. An apparatus as defined in claim 16 further comprising: means for adding a predetermined value to the first value to generate the second value.