Interrupt reduction method in touch screen controller

• US 8,698,756 B2
• Filed: 11/05/2008
• Issued: 04/15/2014
• Est. Priority Date: 11/06/2007
• Status: Active Grant

• Current Assignee: STMicroelectronics Asia Pacific Pte Limited (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Asia Pacific Pte Limited (STMicroelectronics NV)
• Inventors: Ningrat, Kusuma Adi, Ng, Chee Yu
• Primary Examiner(s): Hicks, Charles V
• Application Number:
  US12/265,615
• Publication Number:
  US 20090115740A1
• Time in Patent Office: 1,987 Days
• Field of Search: 345/173
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers

Abstract

Integration of a FIFO memory, FIFO threshold and a timer, along with the other components of a touch screen system allows the number of interrupts to the touch screen controller to be reduced while allowing all point data to be acquired and preserved. In the first touch-detect event, an interrupt is issued to inform the host. The touch screen controller then automatically acquires data as long as touch is detected without host intervention. A FIFO threshold defines the minimum number of data points in FIFO memory before it issues an interrupt to inform the host that data is ready to be fetched. The timer is started once touch is detected. On every single data acquired, the timer is reset. In the event where touch is no longer detected, the timer keeps on counting until the time-up limit is reached. In this event, the touch screen controller will issue an interrupt informing the host the pen is lifted. The host then checks whether there is still data left in FIFO memory to be read.

Claims

1. A touch detect system for coupling between a touch panel and a host, the touch detect system comprising:

a FIFO memory;

a timer that is enabled and reset upon transfer of touch data from the touch panel to the FIFO memory, and that is allowed to timeout after a period where no touch is detected since the last touch; and

a controller that interrupts the host when the timer times out to signal to the host that touch data is available in the FIFO memory for reading.

2. The touch detect system of claim 1, further comprising a data acquisition block that transfers touch data from the touch panel to the FIFO memory.

3. The touch detect system of claim 2, wherein the data acquisition block enables and resets the timer.

4. The touch detect system of claim 1, wherein the controller further interrupts the host when the amount of touch data in the FIFO memory reaches a FIFO threshold.

5. The touch detect system of claim 1, wherein the FIFO threshold is adjustable.

6. A touch screen system comprising:

a data acquisition block;

a host;

a FIFO memory; and

a timer that is enabled and reset upon transfer of touch data from the data acquisition block to the FIFO memory, and that is allowed to timeout after a period where no touch is detected since the last touch; and

a controller that interrupts the host when the timer times out to signal to the host that touch data is available in the FIFO memory for reading.

7. The touch screen system of claim 6 wherein the timer comprises a plurality of J-K flip-flops.

8. The touch screen system of claim 6 wherein the timer comprises reset and clock inputs, and an output.

9. The touch screen system of claim 6 wherein the controller further interrupts the host when the amount of touch data in the FIFO memory reaches.

10. The touch screen system of claim 9 wherein the threshold is adjustable.

11. A method for controlling a touch screen system comprising:

buffering touch data from a touch panel in a FIFO memory;

resetting a timer when touch data is stored in the FIFO memory;

allowing the timer to timeout after a period where no touch is detected since the last touch; and

interrupting a host when the timer times out to signal to the host that touch data is available in the FIFO memory for reading.

12. The method of claim 11 further comprising, interrupting the host when the amount of data in the FIFO memory has reached a threshold value, and for the host to read the data available in the FIFO memory.

13. The method of claim 12 further comprising, adjusting the threshold value.

14. The method of claim 11 wherein all acquired data is stored in the FIFO memory under the control of a touch screen controller.