CN113760129A

CN113760129A - Method for detecting noise of TP chip

Info

Publication number: CN113760129A
Application number: CN202111037718.4A
Authority: CN
Inventors: 杜洪洋; 张金磊
Original assignee: Hefei Songhao Electronic Technology Co ltd
Current assignee: Hefei Songhao Electronic Technology Co ltd
Priority date: 2021-09-06
Filing date: 2021-09-06
Publication date: 2021-12-07

Abstract

The invention discloses a method for detecting noise of a TP (touch panel) chip, which detects the noise through data of an empty scanning channel, and when the TP chip collects voltage difference on the channel through CA (conditional access), the voltage difference is converted into digital data by using an ADC (analog-to-digital converter); when a frame of TP chip is scanned, the CA and the empty scanning channel are in a disconnected state, if no noise exists on the system, the CA outputs VREF constant voltage, and the digital code value converted by the ADC is corresponding to the VREF voltage value; if the system has noise, the CA is interfered, the output voltage deviates from the VREF voltage value, and the digital code value converted by the ADC has deviation. The invention can detect whether the frequency point of TP work has noise in real time, and can detect the noise of a plurality of other frequency points at the same time; if the noise of the current frequency point is considered to be too large, frequency hopping operation is carried out, the noise information of the current environment can be accurately detected through the empty scanning channel method, and the working efficiency is high.

Description

Method for detecting noise of TP chip

Technical Field

The invention relates to the technical field of chip scanning, in particular to a method for detecting TP chip noise.

Background

The TP IC is an important chip for detecting human-computer interaction in life, and people can directly operate a terminal electronic product through the TP IC. After the capacitive TP IC is developed and produced by APPLE corporation, TP technology has developed rapidly and the volume of goods delivered has increased in recent years.

Along with the rapid development of terminal products, the functions of the terminal products are more and more abundant. A mobile phone not only provides the function of communication, but also provides the functions of shopping, playing games and the like. The requirements of these new functions on accuracy are very strict, so the requirements on the performance of TP are also more strict, and today's TP needs to overcome the interference of various noises and accurately and smoothly trace a dot line.

The TP IC carries out voltage acquisition on the channel through the CA, the ADC converts the acquired voltage into a digital signal, and the digital part in the IC carries out data filtering to obtain final cache data. Through the cached data, whether a man-machine interaction event exists can be judged, and the coordinates of the point can be accurately calculated. When there is external noise, the operation of the CA and ADC is disturbed, and the noise is also coupled into the data. Under some frequency points with larger noise, the buffered data receives larger noise interference, which can cause point error reporting or inaccurate line drawing.

In order to prevent noise from affecting the dot and scribe lines, a digital filter is typically added inside the TP IC to filter out some of the noise. However, in a scene where noise interference is serious, only noise can be detected, and the frame data is discarded and subjected to frequency hopping.

In existing solutions, noise is considered to occur instantaneously, with a very high frequency. For this, noise is detected by data separation. When the data is stored, one frame of data of each channel is divided into a first half frame and a second half frame, and the first half frame and the second half frame are respectively cached. After the scanning of a frame of data is completed, the data of the first half frame and the data of the second half frame are subjected to difference, and if the difference value exceeds a configured threshold value, the data of the current frame is considered to be greatly interfered by noise, the frame needs to be discarded and frequency hopping operation is adopted. As shown in fig. 1, in the data separation method, when detecting noise, the frequency of default noise is very high, which is an event occurring instantaneously, so that only data of the first half frame or the second half frame is interfered in data of the first half frame and the second half frame, and therefore, the two frames are differed, and whether noise exists can be detected through a difference value. But the noise is chaotic and may cause inaccurate detection if the frequency of the noise is relatively low in the current scene. Meanwhile, when noise is detected, the data separation method cannot provide enough information, so that the system can know what frequency point the system should hop to, and the efficiency of the whole system is reduced.

Disclosure of Invention

The invention aims to make up for the defects of the prior art and provides a method for detecting noise of a TP chip. The problems mainly solved by the invention include: 1) detecting whether the frequency point of TP operation has noise in real time; 2) simultaneously detecting the noise of a plurality of other frequency points; 3) and if the current frequency point is considered to have overlarge noise, carrying out frequency hopping operation. The invention utilizes the empty scanning channels designed in the TP to carry out noise monitoring, and the number of the empty scanning channels is least limited, and can be a plurality of empty scanning channels or one empty scanning channel. At the beginning of a frame TP, the normal channel and the Null scan channels can be configured to work together, wherein the scan frequency of one Null scan channel Null0 is identical to that of the normal channel, and the scan frequency of the other Null scan channel Nullx is different from that of the normal channel. Finally, whether the current frequency point has noise is judged through the data of Null0, and then the data of Null x can be referred to in real time to decide which frequency point to hop.

The invention is realized by the following technical scheme:

a method for detecting noise of a TP chip detects the noise through data of an empty scanning channel, and comprises the following specific steps:

(1) when the TP chip collects the voltage difference on the channel through the CA, the voltage difference is converted into digital data by using the ADC;

(2) when a frame of TP chip is scanned, the CA and the empty scanning channel are in a disconnected state, if no noise exists on the system, the CA outputs VREF constant voltage, and the digital code value converted by the ADC is corresponding to the VREF voltage value; if the system has noise, the CA is interfered, the output voltage deviates from the VREF voltage value, and the digital code value converted by the ADC has deviation.

The number of the empty scanning channels is multiple, when a frame TP starts scanning, a conventional channel and the empty scanning channels are configured to work together, the scanning frequency of one empty scanning channel, Null0, is configured to be consistent with that of the conventional channel, the scanning frequency of Nullx is different from that of the conventional channel, and the scanning frequency is greater than or less than that of the conventional channel according to a certain percentage.

The Null scan channel is configured to scan before or after the conventional channel, after the scanning is finished, the data of the Null scan channel and the data of the conventional channel are cached, whether noise exists at present is judged through the data of Null0, and when the data of Null0 is close to a code value corresponding to VERF, the noise is considered to be small; and when the code value corresponding to the data of Null0 and the VERF is greatly deviated, the noise of the current frequency point is considered to be large, and the frequency hopping operation needs to be carried out.

Before frequency hopping, Nullx data is read out, which frequency point has relatively low noise is judged according to the data, and finally, frequency hopping is determined to the frequency point with low noise.

IC-integrated circuit;

TP-touch chip;

CA-charge amplifier;

ADC-analog to digital converter;

VREF-reference voltage.

The invention has the advantages that: the invention can detect whether the frequency point of TP work has noise in real time, and can detect the noise of a plurality of other frequency points at the same time; if the noise of the current frequency point is considered to be too large, frequency hopping operation is carried out, the noise information of the current environment can be accurately detected through the empty scanning channel method, and the working efficiency is high.

Drawings

FIG. 1 is a flow chart of noise detection in a data separation method in the prior art.

FIG. 2 is a schematic diagram of an idle scan channel circuit.

FIG. 3 is an overall flow chart of the present invention.

Detailed Description

The invention detects noise through an empty scan channel. The circuit structure is shown in fig. 2, when the TP is the voltage difference on the channel collected by the CA, the voltage difference is converted into digital data by the ADC. When a frame TP scan begins, CA collects its voltage values for the conventional channel. For the empty scanning channel, the CA and the empty scanning channel are in a disconnected state, so that if no noise exists on the system, the voltage of VREF is constantly output by the CA, and the digital code value converted by the ADC is correspondingly the voltage value of VREF; if there is noise on the system and CA is disturbed, the output voltage will deviate from the voltage value of VREF, and the digital code value converted by ADC will also deviate. Therefore, the data of the channel empty scanning channel can accurately detect the noise information of the current environment.

The Null scan channel can support a plurality of Null0, which is configured to have a scan frequency consistent with that of the normal channel, and a scan frequency of Nullx is different from that of the normal channel, and the scan frequency is usually a certain percentage, larger or smaller than that of the normal channel.

The empty scan lane may be configured to scan before or after the regular lane. After the scanning is completed, the data of the empty scanning channel and the data of the normal scanning channel are cached. Judging whether noise exists currently through the data of Null0, and when the data of Null0 is close to the code value corresponding to VERF, considering that the noise is small; and when the code value corresponding to the data of Null0 and the VERF is greatly deviated, the noise of the current frequency point is considered to be large, and the frequency hopping operation needs to be carried out.

Before frequency hopping, Nullx data is read out, which frequency point has relatively low noise is judged according to the data, and finally, frequency hopping is determined to the frequency point with low noise. In practical mass production projects, the number of the air-sweeping channels can be determined after balancing power consumption and performance.

The invention provides a new switchable noise detection mode, the overall flow chart is shown in fig. 3, when the multi-frame data in the digital interior is very noisy, but the overall data flow is relatively smooth, the current system is considered to be interfered by relatively low-frequency noise. At the moment, the processing mode of the digital interior is switched from the data separation method to the empty scanning channel detection method, so that the noise of the frequency point can be accurately detected, effective frequency hopping information is provided, and the TP can immediately hop to the proper frequency point to continue working after the noise is detected. When the TP works at a proper frequency point, the detection mechanism in the digital can be switched to a data separation method from a null scanning channel method, so that part of power consumption is saved.

Claims

1. A method for detecting noise of a TP chip is characterized in that: detecting noise through data of an empty scanning channel, and specifically comprising the following steps:

2. The method of claim 1, wherein the method further comprises: the number of the empty scanning channels is multiple, when a frame TP starts scanning, a conventional channel and the empty scanning channels are configured to work together, the scanning frequency of one empty scanning channel, Null0, is configured to be consistent with that of the conventional channel, the scanning frequency of Nullx is different from that of the conventional channel, and the scanning frequency is greater than or less than that of the conventional channel according to a certain percentage.

3. The method of claim 2, wherein the method further comprises: the Null scan channel is configured to scan before or after the conventional channel, after the scanning is finished, the data of the Null scan channel and the data of the conventional channel are cached, whether noise exists at present is judged through the data of Null0, and when the data of Null0 is close to a code value corresponding to VERF, the noise is considered to be small; and when the code value corresponding to the data of Null0 and the VERF is greatly deviated, the noise of the current frequency point is considered to be large, and the frequency hopping operation needs to be carried out.

4. A method according to claim 3, wherein the method comprises: before frequency hopping, Nullx data is read out, which frequency point has relatively low noise is judged according to the data, and finally, frequency hopping is determined to the frequency point with low noise.