Methods for Discovery, Configuration, and Coordinating Data Communications Between Master and Slave Devices in a Communication System

• US 20130124763A1
• Filed: 10/05/2012
• Published: 05/16/2013
• Est. Priority Date: 10/05/2011
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Kessler, Martin
• Granted Patent: US 8,990,464 B2
• Time in Patent Office: Days
• US Class Current: 710/110
• CPC Class Codes: G06F 11/0754 by exceeding limits
• CPC Class Codes: G06F 11/221 to test buses, lines or interfaces, e.g. stuck-at or open line faults
• CPC Class Codes: G06F 13/364 using independent requests or grants, e.g. using separated request and grant lines
• CPC Class Codes: G06F 13/4072 Drivers or receivers G06F13/4086 takes precedence; for multistate logic circuits H03K19/0002
• CPC Class Codes: G06F 13/426 using an embedded synchronisation, e.g. Firewire bus, Fibre Channel bus, SSA bus
• CPC Class Codes: G06F 13/4282 on a serial bus, e.g. I2C bus, SPI bus on daisy chain buses G06F13/4247
• CPC Class Codes: G06F 13/4295 using an embedded synchronisation
• CPC Class Codes: G06F 2213/0016 Inter-integrated circuit (I2C)
• CPC Class Codes: G06F 9/4411 Configuring for operating with peripheral devices; Loading of device drivers
• CPC Class Codes: H04B 2203/5445 Local network
• CPC Class Codes: H04B 2203/547 via DC power distribution
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 3/548 the power on the line being DC arrangements for feeding power H04L12/10; extracting feeding power from signals H04L25/02
• CPC Class Codes: H04B 3/56 Circuits for coupling, blocking, or by-passing of signals
• CPC Class Codes: H04L 12/40019 Details regarding a bus master
• CPC Class Codes: H04L 12/40026 Details regarding a bus guardian
• CPC Class Codes: H04L 12/40045 Details regarding the feeding of energy to the node from the bus
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 12/4035 in which slots of a TDMA packet structure are assigned based on a contention resolution carried out at a master unit TDM/TDMA multiplex systems per se H04J3/1694; hybrid switching systems H04L12/64
• CPC Class Codes: H04L 2012/40273 the transportation system being a vehicle
• CPC Class Codes: Y02B 70/10 : Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02D 10/00 : Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

Various embodiments of the present invention methods for discovery, configuration, and coordinating data communications between master and slave devices in a communication system. Exemplary embodiments are described with reference to a two-wire point-to-point bus system, although the method can be used in other communication systems. Provisions are included for controlling the sequential powering of the bus and slave devices.

Claims

1. In a communication system having a master device, at least one intermediate slave device, and a last slave device communicatively coupled in series, a method for coordinating data communications between the master device and the slave devices, the method comprising:

periodically transmitting a synchronization control frame by the master device downstream to a first intermediate slave device in the succession of slave devices;

selectively forwarding the synchronization control frame downstream by each successive intermediate slave device to the last slave device;

transmitting by the last slave device a synchronization response frame upstream; and

selectively forwarding the synchronization response frame upstream by each successive intermediate slave device to the master device, wherein;

each slave device derives timing information from the downstream synchronization control frame;

at least one slave device transmits data upstream;

each slave device that receives data from a downstream device selectively transmits the received data upstream and selectively transmits additional data upstream; and

each device that transmits data upstream transmits the data in at least one designated time interval following the synchronization control frame.

2. A method according to claim 1, wherein each slave device is communicatively coupled to a corresponding upstream device by a separate two-wire bus segment.

3. A method according to claim 1, wherein the timing information includes a clock signal for local timing at the slave device and a framing signal indicating the start of a periodic superframe.

4. A method according to claim 1, wherein selectively transmitting data received from a downstream device comprises selectively removing the received data without transmitting the data upstream.

5. A method according to claim 1, further comprising:

selectively transmitting data for at least one slave device by the master device following the synchronization signal, wherein;

each slave device that receives data from an upstream device selectively transmits the received data downstream and selectively transmits additional data downstream; and

each device that transmits downstream data transmits the data in designated time intervals following the synchronization signal.

6. A method according to claim 5, wherein selectively transmitting data received from an upstream device comprises selectively removing the received data without transmitting the data downstream.

7. A method according to claim 1, wherein the synchronization control frame comprises:

a preamble; and

a header, wherein periodically transmitting the synchronization control frame by the master device comprises scrambling a portion of the header.

8. A method according to claim 7, wherein the scrambled portion of the header includes a count field that is changed for each successive transmission to effectively change scrambling parameters for scrambling the remainder of the scrambled portion of the header.

9. A method according to claim 1, wherein the synchronization control frame includes a set of fields selectively used by the master device for conveying communications between an I2C-connected host and a designated slave device.

10. A method according to claim 9, wherein the set of fields includes a field selectively used by the master device to indicate whether a communication is destined for the designated slave device itself or for an I2C device coupled to the designated slave device.

11. A method according to claim 1, wherein the synchronization control frame sent by the master device selectively includes broadcast information intended for all slave devices, and wherein the synchronization response frame includes a broadcast acknowledgement field for indicating whether or not the slave devices received the broadcast information.

12. A method according to claim 1, wherein the synchronization response frame includes an interrupt frame portion to indicate that the slave device requires attention by the master device.

13. A method according to claim 12, wherein the synchronization response frame includes a first CRC field and a second CRC field specifically for the interrupt frame portion.

14. A method according to claim 13, wherein the first CRC field is a 16-bit CRC field, and wherein the second CRC field is a 4-bit CRC field.

15. A method according to claim 1, wherein at least one of:

the upstream data transmitted in designated time intervals includes a parity bit as part of the data frame;

or

the upstream data transmitted in designated time intervals is scrambled.

16. A method according to claim 5, wherein at least one of:

the downstream data transmitted in designated time intervals includes a parity bit as part of the data frame;

or

the downstream data transmitted in designated time intervals is scrambled.

17. In a communication system having a master device and a plurality of slave devices communicatively coupled in series, a method for discovering and configuring slave devices, the method comprising, in each of a number of successive discovery cycles:

transmitting a discovery signal by the master device on a downstream communication link;

by each discovered slave device that receives the discovery signal, forwarding the discovery signal on a downstream communication link; and

by an undiscovered slave device that receives the discovery signal, responding upstream to the discovery signal without forwarding the discovery signal on a downstream communication link.

18. A method according to claim 17, wherein a discovered slave device that is configured as the last discovered slave device and that receives the discovery signal forwards the discovery signal on a downstream communication link and awaits a reply from a downstream slave device while maintaining communications with the master device over an upstream communication link and, upon receiving a discovery response from a downstream slave device, forwards the discovery response from the newly discovered slave device to the master device over the upstream communication link.

19. A method according to claim 18, wherein such discovered slave device that is configured as the last discovered slave device and that receives the discovery signal provides power to the downstream communication link prior to forwarding the discovery signal.

20. A method according to claim 19, wherein providing power to the downstream communication link comprises connecting power from the upstream communication link to the downstream communication link.

21. A method according to claim 20, wherein connecting power from the upstream communication link to the downstream communication link comprises closing at least one switch coupled between the upstream communication link and the downstream communication link.

22. A method according to claim 18, further comprising, upon discovery of the newly discovered slave device:

configuring the newly discovered slave device as the last discovered slave device; and

reconfiguring the previously last discovered slave device as no longer being the last discovered slave device.

23. A method according to claim 17, wherein the discovery signal is part of a synchronization control frame from which the slave devices obtain timing information.

24. A method according to claim 17, wherein the discovery signal includes a response time indicating a time interval for a newly discovered slave device to reply to the discovery signal.