CN114860520B - USB slave equipment extraction detection circuit - Google Patents
USB slave equipment extraction detection circuit Download PDFInfo
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- CN114860520B CN114860520B CN202210428939.2A CN202210428939A CN114860520B CN 114860520 B CN114860520 B CN 114860520B CN 202210428939 A CN202210428939 A CN 202210428939A CN 114860520 B CN114860520 B CN 114860520B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F11/00—Error detection; Error correction; Monitoring
- G06F11/22—Detection or location of defective computer hardware by testing during standby operation or during idle time, e.g. start-up testing
- G06F11/2205—Detection or location of defective computer hardware by testing during standby operation or during idle time, e.g. start-up testing using arrangements specific to the hardware being tested
- G06F11/2221—Detection or location of defective computer hardware by testing during standby operation or during idle time, e.g. start-up testing using arrangements specific to the hardware being tested to test input/output devices or peripheral units
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F9/00—Arrangements for program control, e.g. control units
- G06F9/06—Arrangements for program control, e.g. control units using stored programs, i.e. using an internal store of processing equipment to receive or retain programs
- G06F9/44—Arrangements for executing specific programs
- G06F9/4401—Bootstrapping
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Abstract
A USB slave device pull-out detection circuit comprises an overtime detection module, a detection module and a control module, wherein the overtime detection module is used for detecting the generation of an overtime signal; the SE0 detection module detects whether the signal is an SE0 signal; the hang detection module outputs a hang signal to the pull detection control module after detecting the hang signal; the wake-up module drives the slave equipment to actively initiate a wake-up action according to the wake-up operation starting signal, and if the master equipment is online, the master equipment takes over the wake-up signal and drives an SE0 signal; and the pull-out detection control module is used for sending a wake-up operation starting signal to the wake-up module after receiving the suspension signal, starting the SE0 detection module to carry out SE0 signal detection, and sending an interrupt signal pulled out of the equipment if the received SE0 detection result is 0 so as to finish the pull-out detection of the equipment. The invention aims to detect whether the USB slave device is pulled out or not by adopting a USB suspension circuit and a recovery circuit which are arranged in a chip on the basis of not increasing additional GPIO and detection circuits and not customizing USB phy, thereby reducing the detection cost and improving the detection accuracy.
Description
Technical Field
The present invention relates to a detection circuit, and more particularly, to a USB slave device pull-out detection circuit.
Background
In the USB protocol, only the host and the HUB have the device removal detection function, and as the slave device (device) often does not have the device disconnection detection function, a detection mechanism needs to be designed to determine whether the USB host device is disconnected therefrom.
There are various methods for detecting disconnection of the USB, and the slave device generates a suspend signal after the USB is disconnected from the host as the slave device. When no data exists on the USB bus, the master device can also actively send out a suspend signal to keep the USB bus in a bus idle state for more than 3ms, and the slave device can think that the master device initiates a suspend operation. The slave device is inaccurate if it directly uses the suspend interrupt to determine that the master device is disconnected. If the master device sends data to the USB slave device at regular time, the USB slave device may consider the USB to be disconnected when the USB slave device does not receive the data, but this method needs to transmit a large amount of handshake data to improve the real-time performance, occupies the USB bus, and is not favorable for high-efficiency and high-speed transmission of USB data.
For the USB slave device, a general purpose input/output port GPIO can be used to add a hardware detection circuit to detect that VBUS is disconnected, wherein VBUS is a power supply for the host/HUB to supply power to the USB device, so that the disconnection of the device is judged. The USB host supplies power to the slave device, the USB slave device can detect the power supply pin, a rising edge is generated when the USB is connected, and a falling edge is generated when the USB is disconnected, so that whether the USB host is disconnected or not can be quickly judged. This scheme is effective for when the slave supply power source is not connected to the master VBUS. When the power supply of the master equipment VBUS and the power supply of the slave equipment are connected together, after the VBUS of the master equipment is disconnected, the connected signal can be switched to a main power supply; or certain application scenes require the slave device to reversely charge the master device through the VBUS, and the VBUS disconnection of the master device cannot be judged through the GPIO hardware detection circuit at the moment.
The third scheme is realized by customizing a usb physical layer (usb phy), and the disconnection of the master device when the usb is used as the slave device is judged by using the change of an electrical signal of a data line of the usb phy, but the disconnection is not in accordance with a standard method and can be realized only by specially customizing the physical layer, so that the cost is very high.
First, when the suspension interrupt is used to determine that the slave device is pulled out, a false alarm is generated when the master device actively suspends the slave device but the connection is not really disconnected. The second scheme requires additional GPIOs and hardware detection circuits, which increases the PCB cost and requires more GPIOs. This scheme fails when the master slave VBUS is connected together. Solution three requires customization of the non-standard usb phy. The invention aims to detect whether the USB slave device is pulled out or not by adopting a USB suspension circuit and a recovery circuit which are arranged in a chip on the basis of not increasing additional GPI O and a detection circuit and not customizing USB phy, thereby reducing the detection cost and improving the accuracy, the efficiency and the convenience of detection.
Disclosure of Invention
The invention designs a USB slave device pull-out detection circuit, which is internally arranged in the USB slave device and comprises:
the overtime detection module is used for detecting the generation of an overtime signal, starting an overtime counter according to an overtime counter starting signal, a reset signal and an overtime register configuration signal, and outputting the overtime signal if the overtime counter reaches a count value;
the SE0 detection module comprises an edge detection circuit and an SE0 judgment circuit, the edge detection circuit is started to detect the USB bus state signal after the SE0 detection starting signal is received, the SE0 judgment circuit judges whether the state signal is the SE0 signal or not after the state signal is detected, if the result is true, the SE0 detection result is output to be 1, and if the result is not 0;
the hang detection module outputs a hang signal to the pull-out detection control module after detecting the hang signal;
the wake-up module is used for driving the slave equipment to actively initiate wake-up action according to the wake-up operation starting signal, if the master equipment is on line, the master equipment takes over the wake-up signal and reverses the polarity on the data line to wake up the slave equipment, and the wake-up action is ended by a low-speed EOP signal;
the pull-out detection control module is used for controlling the start and the reset of the overtime detection module after receiving the hang-up signal, sending a wake-up operation start signal to the wake-up module, starting the SE0 detection module to detect the SE0 signal, and sending an interrupt signal pulled out of the equipment if the received SE0 detection result is 0, so as to finish the pull-out detection of the equipment; if the received SE0 detection result is 1, the slave device is judged not to be pulled out.
Further, the low speed device EOP signal is the SE0 state for 2 bit times of the bus followed by the J state for 1 bit time.
Further, after sending a wake-up operation starting signal to the wake-up module, the pull-out detection control module starts a first timeout threshold, and after the first timeout threshold, starts the SE0 detection module to detect the SE0 signal, and if the SE0 signal is detected, it is determined that the slave device is not pulled out.
Further, after the pulling-out detection control module sends a wake-up operation starting signal to the wake-up module, after a first timeout time threshold passes, the SE0 detection module is started to perform SE0 signal detection, if the SE0 signal is not detected, a second timeout time threshold is started and the SE0 signal continues to wait, after the second timeout time threshold passes, if the SE0 signal is detected, it is determined that the slave device is not pulled out, otherwise, it is determined that the slave device is pulled out.
Further, the SE0 detection module may be replaced by a USB signal K state detection module, and if the USB signal state is kept in the K state after the suspension, it may be determined that the slave device has been disconnected.
According to the invention, on the premise of not increasing additional GPI O and detection circuits and not needing customization of USB phy, the USB suspension circuit and the wake-up circuit which are arranged in the chip are adopted to detect whether the USB slave device is pulled out, so that the detection cost is greatly reduced, and the accuracy, the efficiency and the convenience of detection are improved.
Drawings
FIG. 1 shows a block circuit diagram of the SE0 detection module of the present invention;
FIG. 2 shows a block circuit diagram of the timeout detection module of the present invention;
FIG. 3 shows a block diagram of a USB slave device unplugging detection circuit of the present invention;
FIG. 4 shows a flow chart of the USB slave device unplugging detection of the present invention.
Detailed Description
The technical solution of the present invention will be specifically described below with reference to examples.
The invention aims to solve the problem of how to efficiently and conveniently detect whether the slave equipment is pulled out from the USB slave equipment. Detection of unplugging or disconnecting of a slave device from a master device has many application scenarios, such as video greeting cards, which are USB slave devices with batteries. When the computer is not connected, the video greeting card can automatically play the local video. When the video greeting card is connected to a computer, the video greeting card stops playing videos, and the video greeting card is simulated into a U disk device which is used for operating the local video content (including copying, cutting, deleting and the like) of the greeting card in the computer. If the greeting card is pulled out of the computer, the greeting card needs to actively detect the pulling-out signal and then switch to local video playing in time. The invention utilizes the suspend of USB and the remote wake-up mechanism of the slave device to match with the built-in signal detection circuit of the chip to judge whether the slave device is disconnected.
The improved idea of the invention is to actively initiate the wake-up operation after receiving the suspend signal, if the main device is on line, an SE0 signal is generated on the bus, and the SE0 signal detection module detects the SE0 signal and judges that the main device is on line; if the SE0 signal is not detected for more than a certain time, it is determined that the master device has disconnected. SE0 is the usb data line single ended 0 state.
Fig. 1 and fig. 2 are a SE0 detection module and a timeout detection module, respectively, according to the present invention.
The SE0 detection module is used for detecting generation of an SE0 signal and comprises an edge detection circuit and an SE0 judgment circuit, the edge detection circuit is started to detect the USB bus state signal after receiving the SE0 detection starting signal, the SE0 judgment circuit judges whether the state signal is the SE0 signal or not after detecting the state signal, and if the result is true, the SE0 detection result is output to be 1.
The timeout detection module detects generation of a timeout signal. The timeout counter is started according to a timeout counter start signal, a reset signal and a timeout register configuration signal. The timeout counter outputs a timeout ending signal if it reaches a count value configured by software. The timeout counter can be used for detecting 3 times of timeout in the unplugging detection process. The timeout counter may also be reset by the unplug detection control module. The register module serves as a software configuration register for the timeout counter.
FIG. 3 shows a complete circuit block diagram of the USB slave device unplugging detection of the present invention.
And after the suspension detection module detects the suspension signal, the suspension detection module outputs the suspension signal to the pull-out detection control module. There are 2 situations that will generate the suspend signal, and after the master device disconnects, the slave device considers that the suspend signal is received if the master device keeps the data line idle for more than 3 ms. And the awakening module is used for driving the slave equipment to actively initiate awakening action according to the awakening operation starting signal, if the master equipment is on line, the master equipment takes over the awakening signal and reverses the polarity on the data line to awaken the slave equipment, and the awakening module is ended by a low-speed EOP signal. If the slave supports remote wakeup, the slave may initiate a remote wakeup request to the host if the slave has entered id le state for at least 5ms, the slave drives the bus into K state, which must be maintained within 1ms-15ms, which is taken over by the host within 1ms, and the host continues to drive the wakeup signal up to 20ms and ending with the low speed EOP signal. The low speed device EOP signal refers to the SE0 (single ended 0) state of the bus for 2 bit times followed by the J state (differential 0) for 1 bit time.
And the pull-out detection control module receives the hang-up signal, controls the start and the reset of the overtime counter, starts the detection of the wake-up operation signal and the SE0 signal, sends an interrupt signal pulled out from the equipment after receiving the result of the SE0 detection signal and completes the pull-out detection of the slave equipment. The overtime detection module is used for detecting the generation of an overtime signal, starting an overtime counter according to an overtime counter starting signal, a reset signal and an overtime register configuration signal, and outputting the overtime signal if the overtime counter reaches a count value; and the SE0 detection module comprises an edge detection circuit and an SE0 judgment circuit, the edge detection circuit is started to detect the USB bus state signal after the SE0 detection starting signal is received, the SE0 judgment circuit judges whether the state signal is the SE0 signal or not after the state signal is detected, if the result is true, the SE0 detection result is output to be 1, and if the result is not 0, the USB bus state signal is output.
The hang detection module outputs a hang signal to the pull-out detection control module after detecting the hang signal; the wake-up module is used for driving the slave equipment to actively initiate wake-up action according to the wake-up operation starting signal, if the master equipment is on line, the master equipment takes over the wake-up signal and reverses the polarity on the data line to wake up the slave equipment, and the wake-up action is ended by a low-speed EOP signal;
the pull-out detection control module is used for controlling the start and reset of the overtime detection module after receiving the suspension signal, sending a wake-up operation start signal to the wake-up module, starting the SE0 detection module to detect the SE0 signal, and sending an interrupt signal pulled out of the equipment if the received SE0 detection result is 0 so as to finish the pull-out detection of the equipment; if the received SE0 detection result is 1, the slave device is judged not to be pulled out.
FIG. 4 is a flow chart of the detection circuit of the present invention detecting the removal of a USB slave device. The hang detection module sends a hang signal to the pull detection control module after detecting the hang signal; the pulling detection control module starts an overtime counter to obtain an overtime 100ms signal, and the time of 100ms is waited for and the time of 100ms can be adjusted according to the actual situation; the pulling detection control module sends a wake-up operation starting signal to the usb controller, and starts the timeout counter again to monitor the first timeout time threshold, for example, a timeout 15ms signal, and waits for 15ms and 15ms which can be configured by software; the pulling-out detection module starts the SE0 detection module and simultaneously starts the overtime counter again; when the SE0 detection module detects the SE0 signal, the main equipment is on line; otherwise continuing to detect the SE0 signal monitoring a second timeout time threshold, such as until a 20ms timeout exits, then it is determined that the master has been disconnected and the slave is unplugged, and if the SE0 signal is detected during this time, then it is determined that the master is online, 20ms being configurable by software.
The USB signal SE0 detection module can replace a USB signal K state detection module, and if the USB signal state is kept in the K state all the time after the suspension is initiated, the slave equipment can be judged to be disconnected.
The invention can realize the function of detecting the unplugging of the equipment by only adding 4 hardware modules in the existing USB slave equipment controller based on the standard USB phy without customizing USB phy or adopting additional GPI O and a hardware detection circuit on a PCB, and provides a feasible scheme for an application scene of unplugging from the equipment in a live state or a scene of the equipment requiring unplugging detection powered by a battery. The extraction detection of the slave equipment is completely realized by hardware, software does not need to participate, and the hardware generates an interrupt signal to the software after detecting that the slave equipment is extracted.
Finally, it should be noted that the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the same, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.
Claims (5)
1. A USB slave device pull-out detection circuit, the circuit being built-in to the USB slave device, the circuit comprising:
the overtime detection module is used for detecting the generation of an overtime signal, starting an overtime counter according to an overtime counter starting signal, a reset signal and an overtime register configuration signal, and outputting the overtime signal if the overtime counter reaches a count value;
the SE0 detection module comprises an edge detection circuit and an SE0 judgment circuit, the edge detection circuit is started to detect the USB bus state signal after the SE0 detection starting signal is received, the SE0 judgment circuit judges whether the state signal is the SE0 signal or not after the state signal is detected, if the result is true, the SE0 detection result is output to be 1, and if the result is not 0;
the hang detection module outputs a hang signal to the pull-out detection control module after detecting the hang signal;
the wake-up module is used for driving the slave equipment to actively initiate wake-up action according to the wake-up operation starting signal, if the master equipment is on line, the master equipment takes over the wake-up signal and reverses the polarity on the data line to wake up the slave equipment, and the wake-up action is ended by a low-speed EOP signal;
the pull-out detection control module is used for controlling the start and the reset of the overtime detection module after receiving the hang-up signal, sending a wake-up operation start signal to the wake-up module, starting the SE0 detection module to detect the SE0 signal, and sending an interrupt signal pulled out of the equipment if the received SE0 detection result is 0, so as to finish the pull-out detection of the equipment; if the received SE0 detection result is 1, the slave device is judged not to be pulled out.
2. The circuit of claim 1, wherein the low speed device EOP signal is a SE0 state for a bus duration of 2 bit times followed by a J state for a 1 bit time.
3. The circuit according to any of claims 1-2, wherein said unplugging detection control module initiates a first timeout threshold after sending a wake-up operation initiation signal to said wake-up module, initiates said SE0 detection module to perform SE0 signal detection after said first timeout threshold, and determines that the slave device is not unplugged if the SE0 signal is detected.
4. The circuit of claim 3, wherein the unplugging detection control module is configured to, after sending the wake-up operation start signal to the wake-up module, start the SE0 detection module to perform SE0 signal detection after a first timeout threshold, if the SE0 signal is not detected, start a second timeout threshold and continue to wait for the SE0 signal, after the second timeout threshold, if the SE0 signal is detected, determine that the slave device is unplugged, otherwise, determine that the slave device is unplugged.
5. The circuit as claimed in claim 1, wherein the SE0 detection module is replaced by a USB signal K state detection module, and if the USB signal state remains in the K state after suspension, it can be determined that the slave device has been disconnected.
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| CN115981880B (en) * | 2023-03-21 | 2023-06-23 | 深圳云豹智能有限公司 | Method, device, system, storage medium and chip for avoiding deadlock of host access slave |
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| JP2007047909A (en) * | 2005-08-08 | 2007-02-22 | Toshiba Tec Corp | Usb device, and method for evading its standby status |
| CN102063400B (en) * | 2011-01-06 | 2013-03-13 | 天地融科技股份有限公司 | Switching device for general serial bus equipment |
| US8683091B2 (en) * | 2012-06-30 | 2014-03-25 | Intel Corporation | Device disconnect detection |
| JP2019061402A (en) * | 2017-09-26 | 2019-04-18 | セイコーエプソン株式会社 | Electronic apparatus, communication control method and program |
| CN110018976B (en) * | 2018-01-10 | 2022-06-10 | 华为技术有限公司 | Method for USB master device to respond to USB slave device and related device |
| CN112380080B (en) * | 2020-12-02 | 2021-06-08 | 深圳慧能泰半导体科技有限公司 | USB equipment detection system and method |
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| US6460143B1 (en) * | 1999-05-13 | 2002-10-01 | Apple Computer, Inc. | Apparatus and method for awakening bus circuitry from a low power state |
| CN101989246A (en) * | 2009-07-29 | 2011-03-23 | 鸿富锦精密工业（深圳）有限公司 | Electronic device capable of automatically switching master and slave equipment modes of universal serial bus (USB) |
| CN109977042A (en) * | 2019-02-28 | 2019-07-05 | 珠海海奇半导体有限公司 | A kind of USB on-line debugging system and method |
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