A high-sensitivity touch detection circuit
By introducing counter, latch, subtractor and comparator circuits into the touch detection circuit, the hardware complexity and power consumption problems caused by high-frequency clock sampling are solved, and high-sensitivity touch detection is achieved, which is suitable for 32-bit and 8-bit MCU series products.
Patent Information
- Application Number
- CN202521603578.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-30
- Publication Date
- 2026-05-26
- Estimated Expiration
- 2035-07-30
AI Technical Summary
Traditional touch detection systems increase hardware complexity, chip area, and power consumption when using high-frequency clock sampling, leading to higher costs and difficulty in meeting the requirements of low-power design.
A simple digital detection circuit is used, which combines a counter, latch, subtractor and comparator circuit. Touch events are detected by configuring threshold comparison, reducing false alarms and missed alarms, and meeting the high sensitivity requirements of the new generation of MCUs.
It achieves high-sensitivity touch detection, reduces false alarms and false negatives, meets the touch detection requirements of the new generation of MCUs, and is suitable for 32-bit and 8-bit MCU series products.
Smart Images
Figure CN224287506U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of touch detection circuit technology, specifically a high-sensitivity touch detection circuit. Background Technology
[0002] Touch detection circuits are widely used in various electronic devices, especially in smartphones, tablets, home appliances, and industrial control systems. With the development of touch technology, the demands for touch detection accuracy, response speed, and low power consumption are increasing. Traditional touch detection systems typically employ capacitive or resistive touch sensing technology, detecting touch events by sampling the signal output from the touch module and comparing it with a set threshold.
[0003] However, in some applications, to improve the accuracy and sensitivity of touch detection, the system may need to use a high-frequency clock to sample the square wave signal output by the touch module. This method can accurately capture every pulse change, thereby issuing touch interruption signals more promptly and reducing the influence of external interference, ensuring accurate recognition of touch events.
[0004] However, using a high-frequency clock to sample the touch module's output signal also presents several challenges. First, employing an additional high-frequency clock means the chip needs to handle more data sampling frequencies, increasing the complexity of the hardware implementation. Furthermore, the use of a high-frequency clock leads to an increase in chip area, thereby raising the overall cost, especially when high-frequency clock IP licensing is involved, where costs rise further. Second, using a high-frequency clock significantly increases chip power consumption, which becomes a significant issue in applications requiring low-power designs. Therefore, to reduce power consumption, additional low-power processing schemes are typically needed to avoid the energy consumption problems caused by high-frequency clocks. Currently, no solutions have been proposed to address these technical issues. Utility Model Content
[0005] In response to the problems in related technologies, this utility model proposes a high-sensitivity touch detection circuit to overcome the aforementioned technical problems existing in the prior art. The purpose of this utility model is to use a simple digital detection circuit to complete the detection of touch events, and to reduce problems such as false judgment or missed detection by comparing with the configured threshold, so that the touch detection circuit can work more reliably and meet the high requirements of the new generation of MCUs for touch detection.
[0006] To achieve the above objectives, this utility model provides the following technical solution: a high-sensitivity touch detection circuit, comprising: a touch analog circuit, a touch digital circuit, and a CPU processor. The touch analog circuit is used for touch button detection. The touch digital circuit is the digital circuit part of the touch system. The CPU processor is used to process the output from the touch digital circuit, respond to touch interrupts, and configure upper and lower thresholds for touch detection for the touch digital circuit. The touch digital circuit includes a counter circuit, a latch circuit, a subtractor circuit, and a comparator circuit.
[0007] Preferably, the touch simulation circuit transfers charge to an on-chip 60pF capacitor via an on-chip I / O capacitor. When a touch action occurs, the capacitor transferring the charge increases, resulting in a reduction in the number of touch operations.
[0008] Preferably, the counter circuit receives the OUT output from the touch analog circuit, which is used to drive the CP terminal of the D flip-flop group, and the final output of the register group is the number of OUT output pulses.
[0009] Preferably, the latch circuit is used to buffer the output data of the counter circuit.
[0010] Preferably, the subtractor circuit is used to calculate the difference between the current output of the counter circuit and the latched value output by the latch circuit.
[0011] Preferably, the comparator circuit has two detection thresholds: an upper threshold and a lower threshold. If the lower threshold < difference < upper threshold, that is, the difference is within the range of the upper and lower thresholds, it indicates that a touch event has occurred, and an interrupt is sent to the CPU processor. If the difference is outside the range of the upper and lower thresholds, it indicates that no touch event has occurred, and no interrupt is output.
[0012] Compared with the prior art, the beneficial effects of this utility model are:
[0013] This invention relates to a high-sensitivity touch detection circuit. It uses a simple digital detection circuit to detect touch events and interacts with the CPU processor to receive configuration thresholds, reducing false alarms and missed detections, thus ensuring more reliable operation. The configuration interface is open to users, offering flexible configuration and adaptability to various scenarios. It meets the high requirements of next-generation MCUs for touch detection and can be applied in MCU systems, including 32-bit and 8-bit MCU series products. Charge is transferred from on-chip I / O capacitors to internal capacitors. When a touch action occurs, the capacitance for charge transfer increases, reducing the number of transfers. The digital circuit determines whether a touch event has occurred by detecting the number of transfers. Attached Figure Description
[0014] Figure 1 This is a structural block diagram of the entire utility model;
[0015] Figure 2 This is a schematic diagram of the control waveform of this utility model. Attached image description:
[0017] 100. Touch analog circuit; 200. Touch digital circuit; 201. Counter circuit; 202. Latch circuit; 203. Subtractor circuit; 204. Comparator circuit; 300. CPU processor. Detailed Implementation
[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.
[0019] Example
[0020] Please see Figure 1-2 This utility model proposes a technical solution for a high-sensitivity touch detection circuit: a high-sensitivity touch detection circuit, comprising: a touch analog circuit 100, a touch digital circuit 200, and a CPU processor 300. The touch analog circuit 100 is used for touch button detection, the touch digital circuit 200 is the digital circuit part of the touch system, and the CPU processor 300 is used to process the output from the touch digital circuit 200, respond to touch interrupts, and configure upper and lower thresholds for touch detection for the touch digital circuit 200. The touch digital circuit 200 includes a counter circuit 201, a latch circuit 202, a subtractor circuit 203, and a comparator circuit 204.
[0021] In this embodiment, the touch simulation circuit 100 supports a maximum of 32 channels (VIN0~VIN31), and can adjust the resolution, internal capacitor (capacitor for carrying charge), and internal reference voltage. The touch simulation circuit 100 requires a CLK clock. The ENABLE signal enables the module. The START signal starts detection when logic is high. When detection is complete, START needs to be pulled low to wait for the next detection. The OUT signal represents the output of this module. The OUT signal needs to be counted after the rising edge of SRART. The count value corresponds to the capacitor on IO. When there is a touch action, the count value will decrease.
[0022] Furthermore, the touch simulation circuit 100 transfers charge to the on-chip 60pF capacitor through the on-chip I / O capacitor. When a touch action occurs, the capacitor that transfers charge will increase, resulting in a reduction in the number of touch operations.
[0023] Furthermore, the counter circuit 201 receives the OUT output from the touch analog circuit 100, which is used to drive the CP terminal of the D flip-flop group. Finally, the output of the register group is the number of OUT output pulses.
[0024] Furthermore, the latch circuit 202 is used to buffer the output data of the counter circuit 201.
[0025] Furthermore, the subtractor circuit 203 is used to calculate the difference between the current output of the counter circuit 201 and the latched value output by the latch circuit 202.
[0026] Furthermore, the comparator circuit 204 has two detection thresholds: an upper threshold and a lower threshold. When the lower threshold < the difference < the upper threshold, that is, when the difference is within the range of the upper and lower thresholds, it indicates that a touch event has occurred, and an interrupt is sent to the CPU processor 300. If the difference is outside the range of the upper and lower thresholds, it indicates that no touch event has occurred, and there is no interrupt output.
[0027] like Figure 1 As shown, the touch simulation circuit 100 detects a touch event from an external I / O port, outputs a certain number of pulse signals at OUT and sends them to the touch digital circuit 200. The counter circuit 201 receives the output from the touch simulation circuit 100. The output pulses of OUT serve as the CP terminal of the counter in the counter circuit 201, starting asynchronous counting and finally outputting the actual number of pulses at OUT. The latch circuit 202 performs real-time latching of the count output of the counter circuit 201. The subtractor circuit 203 performs subtraction calculation on the current count value of the counter circuit 201 and the previous count value latched by the latch circuit 202 to obtain the difference. The comparator circuit 204 receives the configuration threshold from the CPU processor 300. There are usually two thresholds configured: an upper threshold and a lower threshold. The comparator circuit 204 compares the difference with the threshold. If the difference is within the range of the upper and lower thresholds, it indicates that a touch event has occurred, and an interrupt is sent to the CPU processor 300. If the difference is outside the range of the upper and lower thresholds, it indicates that no touch event has occurred, and no interrupt is output.
[0028] Figure 2 The diagram shows the waveform of the touch analog circuit detection circuit. CLK is the operating clock of the touch analog circuit 100, which is generally derived from the chip itself. The ENABLE signal is the circuit enable signal; it enables the circuit when the logic is high and disables the circuit when the logic is low. The START signal starts touch detection when the logic is high, and needs to be pulled low after detection to wait for the next detection. The OUT signal needs to be counted after the rising edge of SRART. The count value corresponds to the capacitor on the IO. When there is a TOUCH action, the count value will decrease. The OUT signal is output to the touch digital circuit 200 to complete digital post-processing.
[0029] This invention uses a simple digital detection circuit to detect touch events. By interacting with the CPU processor and receiving configuration thresholds from it, it can reduce problems such as false alarms or missed alarms, making the touch detection circuit work more reliably. The configuration interface is open to users, offering flexible configuration and adaptability to various scenarios. It meets the high requirements of the new generation of MCUs for touch detection and can be applied in MCU systems, suitable for 32-bit and 8-bit MCU series products. Charge is transferred from the on-chip I / O capacitor to the on-chip capacitor. When a touch action occurs, the capacitance for transferring charge increases, resulting in a decrease in the number of transfers. The digital circuit determines whether a touch event has occurred by detecting the number of transfers.
[0030] In the description of this utility model, it should be understood that the terms "coaxial", "bottom", "one end", "top", "middle", "other end", "upper", "side", "top", "inner", "front", "center", "both ends", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0031] In this utility model, unless otherwise explicitly specified and limited, the terms "installation", "setting", "connection", "fixing", "screw connection", etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0032] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A high sensitivity touch detection circuit, characterized by, include: The system comprises a touch analog circuit (100), a touch digital circuit (200), and a CPU processor (300). The touch analog circuit (100) is used for touch button detection. The touch digital circuit (200) is the digital circuit part of the touch system. The CPU processor (300) is used to process the output from the touch digital circuit (200), respond to touch interrupts, and configure upper and lower thresholds for touch detection for the touch digital circuit (200). The touch digital circuit (200) includes a counter circuit (201), a latch circuit (202), a subtractor circuit (203), and a comparator circuit (204).
2. The high sensitivity touch detection circuit of claim 1, wherein: The touch simulation circuit (100) transfers charge to the on-chip 60pF capacitor through the on-chip IO capacitor. When there is a touch action, the capacitor that transfers charge will increase, resulting in a reduction in the number of touches.
3. The high sensitivity touch detection circuit of claim 1, wherein: The counter circuit (201) receives the OUT output from the touch analog circuit (100), which is used to drive the CP terminal of the D flip-flop group. Finally, the output of the register group is the number of OUT output pulses.
4. The high sensitivity touch detection circuit of claim 1, wherein: The latch circuit (202) is used to buffer the output data of the counter circuit (201).
5. The high sensitivity touch detection circuit of claim 1, wherein: The subtractor circuit (203) is used to calculate the difference between the current output of the counter circuit (201) and the latched value output by the latch circuit (202).
6. The high sensitivity touch detection circuit of claim 1, wherein: The comparator circuit (204) has two input detection thresholds: an upper threshold and a lower threshold. When the lower threshold < difference < upper threshold, that is, the difference is within the range of the upper and lower thresholds, it indicates that a touch event has occurred and an interrupt is sent to the CPU processor (300). If the difference is outside the range of the upper and lower thresholds, it indicates that no touch event has occurred and no interrupt is output.