INTERRUPT REDUCTION METHOD IN TOUCH SCREEN CONTROLLER

• US 20090115740A1
• Filed: 11/05/2008
• Published: 05/07/2009
• 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: Ng, Chee Yu, Ningrat, Kusuma Adi
• Granted Patent: US 8,698,756 B2
• Time in Patent Office: Days
• 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 comprising a FIFO memory and a timer integrated together between a touch panel and a host for reducing the number of interrupts given to the host without losing acquired touch data.

2. The touch detect system of claim 1 wherein the FIFO memory receives data from a data acquisition block in the touch detect system.

3. The touch detect system of claim 1 wherein the timer receives data from a data acquisition block in the touch detect system.

4. The touch detect system of claim 1 wherein the FIFO memory is in communication with a controller in the touch detect system.

5. The touch detect system of claim 1 wherein the timer is in communication with a controller in the touch detect system.

6. The touch detect system of claim 1 wherein touch data is stored in the FIFO memory if the host is busy.

7. The touch detect system of claim 1 wherein the FIFO memory includes a predetermined FIFO threshold.

8. A touch screen system comprising:

a data acquisition block;

a controller;

a host;

a FIFO memory for receiving data from the data acquisition block and is in communication with the controller; and

a timer for receiving data from the data acquisition block and is in communication with the controller,

wherein the FIFO memory and the timer reduce the number of interrupts to the host without losing data provided by the data acquisition block.

9. The touch screen system of claim 8 wherein the timer comprises a plurality of J-K flip-flops.

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

11. The touch screen system of claim 8 wherein, when there is no touch, the timer is reset.

12. The touch screen system of claim 8 wherein, when a touch is detected the timer is enabled.

13. The touch screen system of claim 8 wherein, if no further data is acquired, the timer continues to run until a threshold is hit and an interrupt is issued.

14. The touch screen system of claim 8 wherein the FIFO memory includes a write pointer and a read pointer.

15. A method for controlling a touch screen system comprising providing a FIFO memory and a timer to store acquired data such that the number of interrupts presented to a host can be minimized.

16. The method of claim 15 further comprising issuing a command for data acquisition and for enabling the timer when touch is detected.

17. The method of claim 15 further comprising resetting the timer every time new data is acquired.

18. The method of claim 15 further comprising, if the number of data entries in the FIFO memory has reach a predetermined value, an interrupt is issued to the host to read all the data available in the FIFO memory.

19. The method of claim 15 further comprising, when no more valid data is acquired, allowing the timer to count until a time-up level is reached and an interrupt is issued to the host to read all the data available in the FIFO memory.

20. The method of claim 15 wherein all acquired data is stored in FIFO memory under the control of a touch screen controller.