Device address assignment in a bus cascade system

• US 8,346,977 B2
• Filed: 08/10/2010
• Issued: 01/01/2013
• Est. Priority Date: 05/20/2010
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Zeng, Xiaojun, Sheng, Kaiya
• Primary Examiner(s): SHIN, CHRISTOPHER B
• Application Number:
  US12/854,041
• Publication Number:
  US 20110289239A1
• Time in Patent Office: 875 Days
• Field of Search: 710 3- 9, 710/33, 710/110, 710/305, 370431-438
• US Class Current: 710/4
• CPC Class Codes: G06F 13/4282 on a serial bus, e.g. I2C bus, SPI bus on daisy chain buses G06F13/4247

Abstract

According to one aspect there is disclosed an apparatus. The apparatus may include a first device. The first device may include a first serial input port configured to receive serial data from at least one of a host MCU and a second device; a first serial output port configured to output the serial data to a third device when the third device is coupled to the first device; a first shift register configured to receive the serial data from the first serial input port; a first multiplexer configured to selectively couple the first serial output port to the first shift register or the first serial input port; and a bus controller configured to receive the serial data from the first serial input port, the bus controller further configured to control the first multiplexer to couple the first serial output port to the first serial input port or the first shift register, based at least in part on the serial data, wherein the serial data includes a command section of a command and at least a portion of a payload section of the command, wherein the command section includes a command code, a target address and an error check and the payload section includes at least one new address and at least one corresponding error check.

Claims

1. An apparatus, comprising:

a first device comprising;

a first serial input port configured to receive serial data from at least one of a host MCU and a second device;

a first serial output port configured to output the serial data to a third device when the third device is coupled to the first device;

a first shift register configured to receive the serial data from the first serial input port;

a first multiplexer configured to selectively couple the first serial output port to the first shift register or the first serial input port; and

a bus controller configured to receive the serial data from the first serial input port, the bus controller further configured to control the first multiplexer to couple the first serial output port to the first serial input port or the first shift register, based at least in part on the serial data,

wherein the serial data comprises a command section of a command and at least a portion of a payload section of the command, wherein the command section comprises a command code, a target address and an error check and the payload section comprises at least one new address and at least one corresponding error check.

2. The first device of claim 1, further comprising:

a second serial input port configured to receive serial data from the third device when the third device is coupled to the first device;

a second serial output port configured to output the serial data to at least one of the second device and the host MCU;

a second shift register configured to receive the serial data from the second serial input port; and

a second multiplexer configured to selectively couple the second serial data output port to the second shift register or the second serial data input port;

wherein the bus controller is further configured to receive the serial data from the second serial input port, the bus controller further configured to control the second multiplexer to selectively couple the second serial output port to the second serial input port, based at least in part on the serial data.

3. The first device of claim 2, further comprising a switch, wherein the switch is configured to couple the first serial input port to the second multiplexer when the switch is closed to provide a test circuit, wherein the bus controller is configured to control the switch.

4. The apparatus of claim 1, wherein the target address a broadcast address and the payload section comprises a plurality of new addresses and the plurality of corresponding error checks.

5. The apparatus of claim 1, wherein the target address is an old address and the payload section comprises one new address and one corresponding error check.

6. The apparatus of claim 1, wherein the first device further comprises a level shifter configured to shift a voltage level of the first device relative to another device when the another device is coupled to the first device.

7. A method for assigning an address to at least one device, the method comprising:

receiving serial data at a first device, wherein the serial data comprises a command section of a command and at least a portion of a payload section of the command, wherein the command section comprises a command code, a target address and a command error check and the payload section comprises at least one new address and at least one corresponding error check;

determining whether the serial data is targeted for the first device based, at least in part, on the command section;

storing a first address in the first device if the serial data is targeted for the first device; and

outputting the first address to a second device or latching the first address in the first device based, at least in part, on the command section.

8. The method of claim 7, wherein the payload comprises a plurality of new addresses, the method further comprising receiving the first address at the second device, receiving a second address at the first device, storing the first address in the second device and storing the second address in the first device, determining whether the serial data comprises an end flag, and outputting the first address to a third device and the second address to the second device or latching the first address in the second device and the second address in the first device, based, at least in part, on whether the serial data comprises the end flag.

9. The method of claim 7, wherein each device comprises a shift register configured to receive the at least one new address.

10. The method of claim 9, wherein the shift register of the first device is further configured to output the first address to the second device.

11. A system, comprising:

a plurality of devices; and

a host controller coupled to a first device of the plurality of devices, the host controller is configured to provide serial data to the first device wherein the serial data comprises a command section of a command and at least a portion of a payload section of the command, the command section comprises a command code, a target address and an error check and the payload section comprises at least one new address and at least one corresponding error check, wherein the command code is configured to cause at least one device to store or output a respective new address;

wherein each device comprises;

a first serial input port configured to receive the serial data,

a first serial output port configured to output the serial data to another device,

a first shift register configured to receive the serial data from the first serial input port,

a first multiplexer configured to selectively couple the first serial output port to the first shift register or the first serial input port, and

a bus controller configured to receive the serial data from the first serial input port, the bus controller further configured to control the first multiplexer to couple the first serial output port to the first serial input port or the first shift, based at least in part on the serial data.

12. The system of claim 11, wherein each device further comprises:

a second serial input port configured to receive the serial data;

a second serial output port configured to output the serial data;

a second shift register configured to receive the serial data from the second serial input port; and

a second multiplexer configured to selectively couple the second serial data output port to the second shift register or the second serial data input port;

wherein the bus controller is further configured to receive the serial data from the second serial input port, the bus controller further configured to control the second multiplexer to selectively couple the second serial output port to the second serial input port, based at least in part on the serial data.

13. The system of claim 12, wherein each device further comprises a switch, wherein the switch is configured to couple the first serial input port to the second multiplexer when the switch is closed to provide a test circuit, wherein the bus controller is configured to control the switch.

14. The system of claim 11, wherein the target address a broadcast address and the payload section comprises a plurality of new addresses and the plurality of corresponding error checks.

15. The system of claim 11, wherein the target address is an old address and the payload section comprises one new address and one corresponding error check.

16. The system of claim 11, wherein each device further comprises a level shifter configured to shift a voltage level of the first device relative to another device when the another device is coupled to the first device.

17. The system of claim 11, wherein the host controller is further coupled to a second device of the plurality of devices.

18. The system of claim 11, wherein the plurality of devices and host controller are coupled in a daisy chain with a common ground, wherein the first serial output port of each device is coupled to a first serial output port of another device or the host controller.

19. The system of claim 11, the system further comprising a plurality of isolators, wherein the plurality of devices and the host controller are coupled in a daisy chain with a non-common ground and a respective isolator is coupled to the first serial output port of each device and a first serial output port of another device or the host controller.

20. The system of claim 12, wherein the plurality of devices and host controller are coupled in a vertical bus with a non-common ground, wherein the first serial input port and the second serial output port of the first device are coupled to the host controller, the first serial output port of the first device is coupled to the first serial input port of another device and the second serial input port of the first device is coupled to the second serial output port of the another device.