Methods and Apparatus to Detect Voltage Class of a Circuit

• US 20080244279A1
• Filed: 03/27/2007
• Published: 10/02/2008
• Est. Priority Date: 03/27/2007
• Status: Active Grant

• Current Assignee: Atmel Rousset S.A.S. (Microchip Technology Incorporated)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Godzinski, Stephane, Bracmard, Gaetan
• Granted Patent: US 7,987,380 B2
• Time in Patent Office: Days
• US Class Current: 713/300
• CPC Class Codes: G06F 1/266 Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips

Abstract

A method including monitoring whether an externally originating signal reaches a predetermined threshold value in a host, producing an output value based on the monitoring, and identifying a power environment for the host based on the output value is described. Also described is a method for determining the power environment of a host. Systems and hosts for implementing the methods are also described.

Claims

1. A host, comprising:

a hardware circuit including a signal monitoring circuit for monitoring an externally originating signal, a status register to store output generated from the hardware circuit;

a software sequence to program the hardware circuit including programming for the signal monitoring circuit to generate an output and programmable control logic to identify a power environment based on the generated output; and

a bus to interface with the status register and obtain the generated output.

2. The host of claim 1, wherein the host is a smart card.

3. The host of claim 1, wherein the host includes one or more communication interfaces.

4. A system for determining the voltage class of an environment, comprising:

a hardware circuit including a signal monitoring circuit, a status register, and programmable control logic; and

a software sequence to program the hardware circuit.

5. The system of claim 4, further comprising one or more control registers.

6. The system of claim 5, further comprising a central processing unit bus that is able to communicate with the one or more control registers and the status register.

7. The system of claim 5, wherein the software sequence can change the values stored in the control registers.

8. The system of claim 7, wherein the values stored in the control registers are used in generating an output from the signal monitoring circuit.

9. The system of claim 4, wherein the signal monitoring circuit comprises an analog supply monitor.

10. The system of claim 4, wherein the signal monitoring circuit comprises a plurality of predetermined, selectable signal levels.

11. The system of claim 10, wherein the predetermined, selectable signal levels comprise:

a first selectable voltage level between class A voltage and class B voltage; and

a second selectable voltage level between class B voltage and class C voltage.

12. The system of claim 4, wherein the signal monitoring circuit is used to monitor a power signal.

13. The system of claim 4, wherein the status register may be modified based on output generated by the signal monitoring circuit.

14. The system of claim 4, wherein an output is generated based on the power supplied to the signal monitoring circuit.

15. The system of claim 4, wherein an output is generated based on the voltage level supplied to the signal monitoring circuit.

16. A method, comprising:

monitoring whether an externally originating signal reaches a predetermined threshold value in a host;

producing an output value based on the monitoring; and

identifying a power environment for the host based on the output value.

17. The method of claim 16, further comprising setting an initial value.

18. The method of claim 16, wherein the host is a smart card.

19. The method of claim 16, wherein the power environment is identified from a plurality of possible power environments.

20. The method of claim 16, wherein the externally originating signal is a power signal.

21. The method of claim 16, wherein the output value is a logical output.

22. A method for determining the power environment of a host;

comprising;

monitoring whether an externally originating signal reaches a predetermined threshold value in a host;

producing a first output value based on the monitoring;

identifying a first power environment for the host if the first output value meets a first specified criteria;

producing a second output value based on the monitoring if the first output value does not meet a first specified criteria; and

identifying a power environment for the host if the second output value meets a second specified criteria.

23. The method of claim 22, further comprising:

producing a third output value based on the monitoring if the second output value does not meet a second specified criteria; and

identifying a power environment for the host if the third output value meets a third specified criteria.

24. The method of claim 23, further comprising:

restarting a sequence with producing a first output value if the third output value does not meet a third specified criteria.

25. The method of claim 23, further comprising using additional output values and additional specified criteria to identify the power environment.

26. The method of claim 22, wherein the first specified criteria and the second specified criteria are the same.

27. The method of claim 22, wherein the host is a smart card.

28. The method of claim 22, wherein each output value is a logical output.

29. A method for determining the power environment of a host, comprising:

means located within the host for monitoring an externally originating signal;

means for producing an output value based on the monitoring; and

means for identifying the power environment of the host based on the output.

30. The method of claim 29, further comprising means for programming a software sequence used in monitoring the externally originating signal.