System and method for improved synchronization between devices

• US 9,971,421 B2
• Filed: 03/06/2014
• Issued: 05/15/2018
• Est. Priority Date: 03/06/2014
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Asia Pacific Pte Limited (STMicroelectronics NV)
• Inventors: Cheong, Chee Weng, Dinu, Leonard Liviu, Guo, Dianbo, Tan, Kien Beng
• Primary Examiner(s): Liu, Shuwang
• Assistant Examiner(s): AHN, SUNG S
• Application Number:
  US14/199,210
• Publication Number:
  US 20150256329A1
• Time in Patent Office: 1,531 Days
• CPC Class Codes: G06F 2203/0384 Wireless input, i.e. hardware and software details of wireless interface arrangements for pointing devices
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/04162 for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware
• CPC Class Codes: H04L 2027/0097 Adaptive synchronisation signals

Abstract

A system and method for synchronizing two devices in communication with each other. When communication between the two devices is to be established, a synchronization process may be invoked. In an embodiment, a first device may initiate sending synchronization signals having rising edge and falling edge pairs. The second device may include a controller configured to receive the synchronization signals. However, noise may inhibit the ability of the controller to correctly receive and/or interpret the synchronization signals. Noise may cause detection components to falsely detect noise as a synchronization signal or may cause detection components to miss detection of an actual synchronization signal. A window generator may be used to generate comparison windows for the controller to detect synchronization signals. Further, the detection window duration and start times may be adjusted based on previously detected (or undetected) synchronization signals in order to compensate for noise overshadowing synchronization signals.

Claims

1. A synchronization detector, comprising:

a charge to voltage converter configured to receive a synchronization signal having a period and edges; and

a window generator configured to generate an activating signal for the charge to voltage converter, the activating signal activating the charge to voltage converter to attempt detection during each of a plurality of time windows including;

a first window for detecting a first subsequent synchronization signal edge in response to a first synchronization signal edge, and

a second window for detecting a second subsequent synchronization signal edge following the first subsequent synchronization signal edge in response to a failure to detect the first subsequent synchronization signal edge within the first window, wherein the second window has a greater duration than the first window;

wherein the window generator is configured to generate the second window after a delay time that is a function of half the period of the synchronization signal and a transient period representing a delay time between occurrence of an edge in the synchronization signal and detection of the edge by the charge to voltage converter;

wherein the charge to voltage converter is configured to be deactivated by the activating signal outside of each of the plurality of time windows;

wherein each of the first and second windows have a duration of less than the period of the synchronization signal.

2. The synchronization detector of claim 1, wherein the first synchronization signal edge comprises a rising edge.

3. The synchronization detector of claim 1, wherein the duration of the generated first window is approximately one tenth of the period of the synchronization signal plus a detection delay time.

4. The synchronization detector of claim 1, wherein the window generator generates the first window after a delay time equal to approximately half of the period of the synchronization signal.

5. The synchronization detector of claim 1, wherein the window generator is further configured to generate another window in response to detection of the first subsequent synchronization signal edge.

6. The synchronization detector of claim 1, wherein the window generator is further configured to generate another window in response to the first subsequent synchronization signal edge after a delay time equal to approximately half the period of the synchronization signal.

7. The synchronization detector of claim 1, wherein the window generator is further configured to generate the second window after the delay time that is the function of half the period of the synchronization signal and the transient period representing the delay time between occurrence of the edge in the synchronization signal, less half of a frequency error deviation in the period of the synchronization signal.

8. A synchronization detector, comprising:

a charge to voltage converter configured to receive a synchronization signal having a period and edges; and

a window generator configured to generate an activating signal for the charge to voltage converter, the activating signal activating the charge to voltage converter to attempt detection during windows for detecting the edges of the synchronization signal, the windows each having a duration related to the period of the synchronization signal and whether an immediately preceding edge of the synchronization signal was detected in an immediately preceding window;

wherein the charge to voltage converter is configured to deactivated by the activating signal outside of each of the generated windows;

wherein each of the generated windows has a duration of less than the period of the synchronization signal;

wherein the window generator is configured to generate the activating signal after an delay time that is a function of half the period of the synchronization signal and a transient period representing a delay time between occurrence of an edge in the synchronization signal and detection of the edge by the charge to voltage converter.

9. The synchronization detector of claim 8, wherein the synchronization signal comprises edges such that a first and second edges are within the period of the synchronization signal.

10. The synchronization detector of claim 8, wherein the generated window duration is at least approximately one tenth of the period of the synchronization signal plus a detection delay time.

11. The synchronization detector of claim 8, wherein the window generator is further configured to generate the windows after a delay time starting from the immediately preceding edge equal to approximately half of the period of the synchronization signal less the transient period representing the delay time between occurrence of an edge in the synchronization signal and detection of the edge by the charge to voltage converter, and less half of a frequency error deviation in the period of the synchronization signal.

12. An integrated circuit, comprising:

a converter configured to receive a synchronization signal having a period and edges; and

a window generator configured to generate an activating signal for the converter, the activating signal activating the converter to attempt detection during a window for detecting a subsequent synchronization signal edge in response to a first synchronization edge;

wherein the converter is deactivated by the activating signal outside of the window;

wherein the window has a duration of less than the period of the synchronization signal;

wherein the window generator is configured to generate the activating signal after a delay time that is a function of half the period of the synchronization signal and a transient period representing a delay time between occurrence of an edge in the synchronization signal and detection of the edge by the converter.

13. The integrated circuit of claim 12, wherein the converter comprises a charge-to-voltage converter.

14. The integrated circuit of claim 12, further comprising a comparator coupled to the converter and configured to generate a comparison signal for triggering the window generator.

15. The integrated circuit of claim 12, wherein the converter and window generator are circuits is integrated within a single integrated circuit die.

16. The integrated circuit of claim 12, further comprising a processor configured to implement the converter and the window generator.

17. A synchronization detector, comprising:

a charge to voltage converter configured to receive a synchronization signal having a period and signal edges; and

a window generator configured to generate an activating signal for the charge to voltage converter, the activating signal activating the charge to voltage converter to attempt detection during windows for detecting one of signal edges of the synchronization signal in response to previous detection of a first synchronization edge wherein said window has a first duration of less than the period of the synchronization signal if the previous detection was for an immediately preceding signal edge and a second duration of less than the period of the synchronization signal, longer than the first duration, if the previous detection was not for the immediately preceding signal edge;

wherein the window generator is configured to generate the activating signal after a delay time that is a function of half the period of the synchronization signal and a transient period representing a delay time between occurrence of an edge in the synchronization signal and detection of the edge by the charge to voltage converter;

wherein the charge to voltage converter is configured to deactivated by the activating signal outside of the window.

18. A system, comprising:

an input device configured to generate a synchronization signal having a period and edges;

a computing device configured to synchronize with the input device, the computing device having;

a charge to voltage converter configured to receive the synchronization signal from the input device; and

a window generator configured to generate an activating signal for the charge to voltage converter, the activating signal activating the charge to voltage converter to attempt detection during a window for detecting a signal edge of the received synchronization signal, said window opening with at a time delay from a previously detected signal edge and having a duration that is less than a duration of the synchronization signal and is dependent on whether an immediately preceding signal edge was detected and a transient period representing a delay time between occurrence of an edge in the synchronization signal and detection of the edge by the charge to voltage converter;

wherein the charge to voltage converter is configured to be deactivated by the activating signal outside of the window.

19. The system of claim 18, wherein the input device comprises a stylus and the computing device comprises a touch screen configured to capacitively communicate with the stylus.

20. A method, comprising:

receiving, at a charge to voltage converter, a synchronization signal having a period and edges;

generating an activating signal for the charge to voltage converter, the activating signal activating the charge to voltage converter to attempt detection during;

a first window for detecting a first subsequent synchronization signal edge in response to a first synchronization signal edge;

a second window for detecting a second subsequent synchronization signal edge following the first subsequent synchronization signal edge in response to a failure to detect the first subsequent synchronization signal edge within the first window, wherein the second window has a greater duration than the first window;

wherein the second window is generated after a delay time that is a function of half the period of the synchronization signal and a transient period representing a delay time between occurrence of an edge in the synchronization signal and detection of the edge; and

deactivating the charge to voltage converter outside of the first and the second window using the activating signal;

wherein the first and the second windows have a duration of less than the period of the synchronization signal.

21. The method of claim 20, further comprising detecting the first synchronization signal edge as a rising edge.

22. The method of claim 20, further comprising detecting the first synchronization signal edge as a falling edge.

23. The method of claim 20, wherein the duration of the first window is approximately one tenth of a period of the synchronization signal plus a detection delay time.

24. The method of claim 20, wherein the first window is generated after the delay time equal that is a function of half of the period of the synchronization signal and the transient period representing the delay time between occurrence of an edge in the synchronization signal and detection of the edge, less half of a frequency error deviation in the period of the synchronization signal.

25. The method of claim 20, further comprising generating another window in response to the first subsequent synchronization signal edge.

26. The method of claim 20, further comprising generating another window in response to the first subsequent synchronization signal edge after a delay time equal to approximately half a period of the synchronization signal.