INPUT DEVICE TRANSMITTER PATH ERROR DIAGNOSIS

• US 20140159742A1
• Filed: 02/13/2014
• Published: 06/12/2014
• Est. Priority Date: 01/25/2011
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: FANG, Wen
• Granted Patent: US 9,304,162 B2
• Time in Patent Office: Days
• US Class Current: 324/548
• CPC Class Codes: G01R 31/2832 Specific tests of electronic circuits not provided for elsewhere G01R31/2801, G01R31/316 take precedence
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

A processing system configured for capacitive sensing comprises transmitter circuitry, a first internal diagnostic mechanism, and a determination module. The transmitter circuitry is coupled with a first transmitter path of a plurality of transmitter paths and configured to transmit a first transmitter signal with the first transmitter path, wherein each transmitter path of the plurality of transmitter paths is configured for capacitive sensing. The first internal diagnostic mechanism is coupled to a second transmitter path of the plurality of transmitter paths. The first internal diagnostic mechanism is configured to acquire a first resulting signal while the transmitter circuitry transmits the first transmitter signal with the first transmitter path, wherein the first internal diagnostic mechanism comprises a selectable leakage path coupled to the transmitter circuitry. The determination module is further configured to determine that the first transmitter path is ohmically coupled to the second transmitter path of the plurality of transmitter paths based upon the first resulting signal.

Claims

1. A processing system configured for capacitive sensing, said processing system comprising:

transmitter circuitry coupled with a first transmitter path of a plurality of transmitter paths and configured to transmit a first transmitter signal with said first transmitter path, wherein each transmitter path of said plurality of transmitter paths is configured for capacitive sensing;

a first internal diagnostic mechanism coupled to a second transmitter path of said plurality of transmitter paths, said first internal diagnostic mechanism configured to acquire a first resulting signal while said transmitter circuitry transmits said first transmitter signal with said first transmitter path, wherein said first internal diagnostic mechanism comprises a selectable leakage path coupled to said transmitter circuitry; and

a determination module is further configured to determine that said first transmitter path is ohmically coupled to said second transmitter path of said plurality of transmitter paths based upon said first resulting signal.

2. The processing system of claim 1, wherein said determination module is further configured to determine when said first transmitter path is ohmically coupled to a third transmitter path of said plurality of transmitter paths based on a second resulting signal at an output of a second internal diagnostic mechanism coupled with said third transmitter path, wherein said second resulting signal is acquired via said output of said second internal diagnostic mechanism while said transmitter circuitry transmits said first transmitter signal with said first transmitter path.

3. The processing system of claim 1, wherein said transmitter circuitry is further configured to transmit a second transmitter signal on said second transmitter path while said first transmitter signal is transmitted on said first transmitter path, wherein said second transmitter signal is of opposite polarity to said first transmitter signal.

4. The processing system of claim 1 further comprising a second internal diagnostic mechanism coupled said first transmitter path, wherein:

said transmitter circuitry is further configured to transmit a second transmitter signal with said second transmitter path;

said second internal diagnostic mechanism is further configured to enable an output of said second internal diagnostic mechanism; and

said determination module is further configured to determine when said first transmitter path is ohmically coupled to a reference potential based on a measurement of a second resulting signal, wherein said second resulting signal is acquired via said output of said second internal diagnostic mechanism while said transmitter circuitry transmits said second transmitter signal with said second transmitter path.

5. The processing system of claim 1, wherein said transmitter circuitry is further configured to transmit said first transmitter signal with said second transmitter path;

and

said determination module is configured to determine when said second transmitter path is ohmically coupled to a third transmitter path of said plurality of transmitter paths based on a second resulting signal at an output of a second internal diagnostic mechanism coupled with said third transmitter path, wherein said second resulting signal is acquired via said output of said second internal diagnostic mechanism while said transmitter circuitry transmits said first transmitter signal with said second transmitter path.

6. The processing system of claim 1, wherein said first internal diagnostic mechanism is configured to couple said second transmitter path with a constant voltage during a first time period and wherein said determination module is configured to determine when a discontinuity exists within said second transmitter path based on an output of said first internal diagnostic mechanism during a second time period, wherein said second time period occurs after said first time period.

7. The processing system of claim 1, wherein said determination module is further configured to determine when said first transmitter path is ohmically coupled to at least one receiver path of a capacitive sensing device based on a comparison of a measurement of capacitive loading of said first transmitter path to a predetermined capacitive loading threshold value.

8. The processing system of claim 1, wherein said first internal diagnostic mechanism further comprises a buffered output coupled with said selectable leakage path and said second transmitter path, and a selectable diagnostic node coupled as an input select of said selectable leakage path.

9. The processing system of claim 1, wherein said selectable leakage path comprises a weak pull-down transistor.

10. The processing system of claim 1, wherein said selectable leakage path comprises a current source.

11. The processing system of claim 1, wherein said first internal diagnostic mechanism is further coupled to a third transmitter path of said plurality of transmitter paths, said first internal diagnostic mechanism configured to acquire a second resulting signal with said third transmitter path while said transmitter circuitry transmits said first transmitter signal with said first transmitter path.

12. A capacitive sensing device comprising:

a plurality of transmitter paths, wherein each transmitter path of said plurality of transmitter paths is configured for capacitive sensing; and

a processing system coupled with said plurality of transmitter paths, said processing system configured to;

transmit a first transmitter signal with a first transmitter path of said plurality of transmitter paths in an input device;

acquire a first resulting signal from an output of a first internal diagnostic mechanism coupled to a second transmitter path of said plurality of transmitter paths while said processing system transmits said first transmitter signal with said first transmitter path; and

determine when said first transmitter path is ohmically coupled to said second transmitter path of said plurality of transmitter paths based upon said first resulting signal.

13. The capacitive sensing device of claim 12, wherein said processing system is further configured to determine when said first transmitter path is ohmically coupled to a third transmitter path of said plurality of transmitter paths based on a second resulting signal at an output of a second internal diagnostic mechanism coupled with said third transmitter path, wherein said second resulting signal is acquired via said output of said second internal diagnostic mechanism while said processing system transmits said first transmitter signal with said first transmitter path.

14. The capacitive sensing device of claim 12, wherein said processing system is further configured to:

transmit a second transmitter signal with said second transmitter path;

enable an output of a second internal diagnostic mechanism coupled to said first transmitter path; and

determine when said first transmitter path is ohmically coupled to a reference potential based on a measurement of a second resulting signal, wherein said second resulting signal is acquired via said output of said second internal diagnostic mechanism while transmitting said second transmitter signal with said second transmitter path.

15. The capacitive sensing device of claim 12, wherein said processing system is further configured to transmit said first transmitter signal with said second transmitter path and to determine when said second transmitter path is ohmically coupled to a third transmitter path of said plurality of transmitter paths based on a second resulting signal at an output of a second internal diagnostic mechanism coupled with said third transmitter path, wherein said second resulting signal is acquired via said output of said second internal diagnostic mechanism while transmitting said first transmitter signal with said second transmitter path.

16. The capacitive sensing device of claim 12, wherein said processing system is configured to couple said second transmitter path with a constant voltage during a first time period via said first internal diagnostic mechanism and wherein said processing system is further configured to determine when a discontinuity exists within said second transmitter path based on an output of said first internal diagnostic mechanism during a second time period, wherein said second time period occurs after said first time period.

17. The capacitive sensing device of claim 12, wherein an output of said first internal diagnostic mechanism is coupled with a multiplexer.

18. A method of input device transmitter path error diagnosis, said method comprising:

transmitting a first transmitter signal with a first transmitter path of a plurality of transmitter paths in an input device, wherein each transmitter path of said plurality of transmitter paths is configured for capacitive sensing;

acquiring a first resulting signal from an output of a first internal diagnostic mechanism coupled to a second transmitter path of said plurality of transmitter paths while transmitting on said first transmitter signal with said first transmitter path; and

determining when said first transmitter path is ohmically coupled to said second transmitter path of said plurality of transmitter paths based upon said first resulting signal.

19. The method as recited in claim 18 further comprising:

determining when said first transmitter path is ohmically coupled to a third transmitter path of said plurality of transmitter paths based on a second resulting signal at an output of a second internal diagnostic mechanism coupled with said third transmitter path, wherein said second resulting signal is acquired via said output of said second internal diagnostic mechanism while transmitting said first transmitter signal with said first transmitter path.

20. The method as recited in claim 18 further comprising:

coupling said second transmitter path with a constant voltage during a first time period via said first internal diagnostic mechanism and determining when a discontinuity exists within said second transmitter path based on an output of said first internal diagnostic mechanism during a second time period, wherein said second time period occurs after said first time period.