Signal processing

• US 8,533,654 B2
• Filed: 11/07/2011
• Issued: 09/10/2013
• Est. Priority Date: 10/21/2008
• Status: Expired due to Fees

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Yilmaz, Esat, Philipp, Harald
• Primary Examiner(s): LIN, SUN J
• Application Number:
  US13/290,807
• Publication Number:
  US 20120112770A1
• Time in Patent Office: 673 Days
• Field of Search: 716/108, 716/113, 716/115, 716/134, 716/136, 327/551
• US Class Current: 716/136
• CPC Class Codes: G06F 2218/04 Denoising
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 2217/960705 Safety of capacitive touch and proximity switches, e.g. increasing reliability, fail-safe
• CPC Class Codes: H03K 5/1252 Suppression or limitation of noise or interference specially adapted for transmission systems H04B15/00, H04L25/08

Abstract

An iterative method may comprise obtaining a current input signal value for a current iteration, comparing the current input signal value with an output signal value determined in a previous iteration, updating a counter value determined in the previous iteration based on the comparison such that the updated counter value replaces the previously determined counter value, determining a slew value based on the counter value, and adding the slew value to the previously determined output signal value to generate a new current output signal value. Different slew values may be added to the previous output signal to obtain a new output signal. The counter value is updated to reflect recent trends in the input signals. For example, if the input signal is on an upward trend, the counter value may be relatively high because it is incremented each time an input signal exceeds a previously determined output signal.

Claims

1. A method comprising:

comparing, using one or more microcontrollers, a current input signal value for a current iteration with a previous output signal value;

updating, using the one or more microcontrollers, a counter value determined in a previous iteration based on a result of the comparing between the current input signal value and the previous output signal value;

determining, using the one or more microcontrollers, a slew value based on the updated counter value; and

adding, using the one or more microcontrollers, the slew value to the previous output signal value to generate a current output signal value.

2. An apparatus comprising:

a storage component; and

a processing component operable to perform operations comprising;

comparing a current input signal value for a current iteration with a previous output signal value;

updating a counter value based on a result of the comparing between the current input signal value and the previous output signal value;

determining a slew value based on the updated counter value; and

adding the slew value to the previous output signal value to generate a current output signal value.

3. The apparatus of claim 2, wherein the determining the slew value is performed based on a size of a difference between the updated counter value and a pre-defined base value.

4. The apparatus of claim 3, wherein the determining the slew value is made such that slew values of greater magnitude are determined if the updated counter value is farther away from the pre-defined base value than if the updated counter value is nearer to the pre-defined base value.

5. The apparatus of claim 2, wherein a relationship between counter values and magnitudes of slew values is a non-linear relationship.

6. The apparatus of claim 2, wherein the slew value is determined from the updated counter value by reference to a pre-defined look-up table.

7. The apparatus of claim 2, wherein the updating the counter value is performed differently depending on whether the counter value is beyond a threshold counter value.

8. The apparatus of claim 2, wherein the updating the counter value comprises:

comparing the updated counter value with a pre-defined threshold counter value, and

incrementing, decrementing, or resetting the counter value to a base value depending on both a result of the comparing the updated counter value with the pre-defined threshold counter value and the result of the comparing the current input signal value with the previous output signal value.

9. The apparatus of claim 2, wherein the operations further comprise setting, if the counter value is beyond a defined threshold value and the updating the counter value brought the updated counter value closer to the defined threshold value, the current output signal value to the previous output signal value.

10. The apparatus of claim 2, wherein the operations further comprise setting, if the current input signal value is within a range bound by the previous output signal value and the current output signal value, the current output signal value to the current input signal value.

11. The apparatus of claim 2, wherein the updated counter value is constrained to values between a predefined maximum counter value and a pre-defined minimum counter value.

12. The apparatus of claim 2, wherein the operations further comprise initializing a counter value and defining a notional previous output signal value for a first iteration.

13. The apparatus of claim 12, wherein the notional previous output signal value for the first iteration is one of the input signal values.

14. The apparatus of claim 2, wherein the slew value is defined to a higher precision than the input signal values.

15. The apparatus of claim 2, wherein the current output signal value is independent of a magnitude of a difference between the current input signal value and the previous output signal value.

16. The apparatus of claim 2, wherein the input signal values represent measurements from a sensing element of a capacitive sensor.

17. The apparatus of claim 2, wherein the operations further comprise providing the output signal value on an output signal line.

18. One or more non-transitory computer-readable storage media that embody logic that is operable, when executed by a processor, to perform operations comprising:

comparing a current input signal value for a current iteration with a previous output signal value;

updating a counter value based on a result of the comparing between the current input signal value and the previous output signal value;

determining a slew value based on the updated counter value; and

adding the slew value to the previous output signal value to generate a current output signal value.

19. The one or more non-transitory computer-readable storage media of claim 18, wherein the determining the slew value is performed based on a size of a difference between the updated counter value and a pre-defined base value.

20. The one or more non-transitory computer-readable storage media of claim 18, wherein the operations further comprise setting, if the counter value is beyond a defined threshold value and the updating the counter value brought the updated counter value closer to the defined threshold value, the current output signal value to the previous output signal value.