TWI753379B - Always-on system with multi-layer power management - Google Patents

Abstract

An always-on system with multi-layer power management includes an always-on portion that is powered in shutdown state and all power states while rest portions of the system are not powered in the shutdown state; a memory unit that is powered in sleep state to retain data in the memory unit; an input interface that is powered only in event detection state, in which at least one captured image is received from an image sensor, the event detection state beginning when a trigger signal is issued; an event monitor that detects motion in the captured image; a digital signal processor (DSP) that is powered only in computer vision state to perform image identification on the captured image if motion is detected; and an output interface is powered only in the computer vision state, a result of the DSP being outputted via the output interface.

Description

Always-on system with multi-layer power management

The present invention relates to power management, and more particularly, to an always-on system with multiple layers of power management.

Always-on sensing technology can be applied to systems with limited power, such as battery-operated Internet of Things (IoT), to substantially reduce overall power consumption with high performance. Because contemporary systems are more functional and complex, traditional always-on systems cannot effectively manage power consumption.

Passive infrared (PIR) sensors, ambient light sensors or temperature sensors are commonly used in event-trigger systems to save power. However, the traditional always-on system triggered by the sensor still cannot effectively save a lot of power consumption due to the frequent false alarms of the sensor.

Therefore, there is an urgent need to propose a novel mechanism to overcome many deficiencies of power management in conventional systems.

In view of the above, one of the objectives of the embodiments of the present invention is to provide an always-on system with multi-layer power management to effectively manage the power consumption of the always-on application.

According to an embodiment of the present invention, the always-on system with multi-layer power management has shutdown, sleep, event detection and computer vision states. The always-on system includes a permanent-on part, a memory unit, an input interface, an event monitor, a digital signal processor and an output interface. In the shutdown state, part of the power supply is always turned on, but the The rest of the open system is not powered. The memory unit is powered in the sleep state to keep the data in the memory unit. The input interface is only powered in the event detection state, receives at least one captured image from the image sensor, and starts the event detection state when a trigger signal is sent. The event monitor detects movement in the captured image. The digital signal processor is powered only in the computer vision state and performs image recognition on the captured image when motion is detected. The output interface is powered only in the computer vision state to output the results of the digital signal processor.

100: always-on system with multi-layer power management

400: always-on system with multi-layer power management

10: Power Management Unit

10A: PWM unit

10B: Low pressure drop regulator

11: Timer

12: Non-image sensing unit

13: Memory unit

14: Input interface

15: Oscillator

16: Data bus

17: Encoder

18: Event Monitor

19: Digital Signal Processor

20: Output interface

101: External sensor

102: Image sensor

103: External Electronics

104: External memory unit

31: The first trigger signal

32: Second trigger signal

SD: shutdown

SLP: sleep

ED: Event Detection

TR: trigger

RX: receive

CV: Computer Vision

The first figure shows a block diagram of an always-on system with multi-layer power management according to an embodiment of the present invention.

The table in the second figure shows the power states of the system of the embodiment of the present invention.

The timing diagram of the third figure shows the corresponding signals for power management in the time domain.

FIG. 4 shows a block diagram of an always-on system with multi-layer power management according to a variant embodiment of the present invention.

The first figure shows a block diagram of an always-on system 100 with multi-layer power management according to an embodiment of the present invention. The always-on system with multi-layer power management (hereinafter referred to as the system) 100 can be fabricated on a system-on-a-chip (SoC), and all components of the system are integrated on a single microchip.

According to one of the features of this embodiment, the multi-layer power management of the system 100 may include at least the following power states: shutdown (SD), sleep (SLP), event detection (ED), and computer vision (computer vision) vision, CV). The table in the second figure shows the power state of the system 100 according to the embodiment of the present invention, and the timing diagram in the third figure shows the corresponding signals of power management in the time domain.

In this embodiment, the system 100 may include a permanently open portion (marked as SD). In the shutdown (SD) state, power (eg, battery power) is supplied to the always-on portion, while the rest of the system 100 is not powered. The always-on part is powered in all states.

In one embodiment, the always-on portion may include a power management unit 10, which may include at least one pulse width modulation (PWM) unit 10A and at least one voltage regulator according to system specifications. regulator) (eg, low pressure drop (LDO) regulator 10B). The always-on portion may also include a timer 11 that counts down from a preset time interval to (regularly) issue a (first) trigger signal 31 (third figure) to indicate that the preset time interval has expired. The always-on part may also include a non-image sensing unit 12 for detecting events notified by the external sensor 101, and (irregularly) issuing a (second) trigger signal 32 (third figure) to indicate a pre- Suppose the event has occurred. The external sensor 101 may be a passive infrared (PIR) sensor, an ambient light sensor, a temperature sensor or a sound sensor. The system 100 may include a memory unit 13 that is powered in a sleep state to retain data in the memory unit 13 . In one embodiment, the memory unit 13 is only powered off in a shutdown (SD) state.

As illustrated in the third figure, when the timer 11 or the external sensor 101 sends out the trigger signal 31/32, the event detection (ED) state is started. In this embodiment, the event detection (ED) state can be divided into two sub-states: a trigger (TR) sub-state and a receive (RX) sub-state, which are executed sequentially.

In the trigger (TR) sub-state, the input interface 14 of the system 100 is powered and activated, and is regulated by the oscillator 15 . The input interface 14 can output the clock signal and the control signal to the (external) image sensor 102 to activate the image sensor 102 . Next, the activated image sensor 102 can capture at least one image. In one embodiment, the input interface 14 and the oscillator 15 are powered only in the trigger (TR) sub-state.

In the receive (RX) sub-state, the data bus 16, encoder 17, and event monitor 18 of the system 100 are powered. The captured images are received (or streamed) by the data bus 16 and encoded by the encoder 17 . Next, the event detector 18 performs (image-based) motion detection on the encoded image to detect motion within the image. For example, it is determined whether the image difference between the current image and the previous image is greater than a predetermined threshold. When the image difference is greater than the preset threshold, motion is detected, otherwise no motion is detected. In one embodiment, the data bus 16, encoder 17 and event monitor 18 are powered only in the receive (RX) sub-state. In an alternative embodiment, the output interface 14, oscillator 15, data bus 16, encoder 17 and event monitor 18 are powered in the event detection (ED) state. In one embodiment, the supply voltage of the memory unit 13 in the receive (RX) sub-state is greater than the supply voltage in the sleep (SLP) state.

If the event monitor 18 detects movement, the system 100 may enter a computer vision (CV) state and power a digital signal processor (DSP) 19 and output interface 20 . Among them, the digital signal processor 19 can code) to capture images and perform image recognition to recognize faces. It is worth noting that the processing power of the digital signal processor 19 for recognizing the human face in the image is much greater than that of the event monitor 18 for detecting movement in the image. In one embodiment, the digital signal processor (DSP) 19 and the output interface 20 are powered only in the computer vision (CV) state.

When the image recognition is completed, the results of the digital image processor 19 can be output to the external electronic device 103 through the output interface 20 for further operations and processing. The results of the digital image processor 19 can also be output through the output interface 20 and stored in the external memory unit 104 . In one embodiment, the external memory unit 104 can store a preset database for assisting the digital image processor 19 to perform image recognition.

FIG. 4 shows a block diagram of an always-on system 400 with multi-layer power management according to a variant embodiment of the present invention. The always-on system with multi-layer power management (hereinafter referred to as the system) 400 is similar to the system 100 (the first figure), and the differences will be described as follows. In this embodiment, the event monitor 18 is provided on the (external) image sensor 102 . When the event monitor 18 of the image sensor 102 detects motion, the event monitor 18 can notify the non-image sensing unit 12, causing the system 400 to enter a computer vision (CV) state so that the digital image processor 19 can The image performs image recognition to recognize faces.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the scope of the patent application of the present invention; all other equivalent changes or modifications made without departing from the spirit disclosed in the invention shall be included in the following within the scope of the patent application.

100: always-on system with multi-layer power management

10: Power Management Unit

11: Timer

12: Non-image sensing unit

13: Memory unit

14: Input interface

15: Oscillator

16: Data bus

17: Encoder

18: Event Monitor

19: Digital Signal Processor

20: Output interface

101: External sensor

102: Image sensor

103: External Electronics

104: External memory unit

Claims (17)

An always-on system with multi-layer power management, with shutdown, sleep, event detection and computer vision states, the always-on system includes: an always-on part, in the shutdown state, the always-on part supplies power, but the always-on system The remaining part is not powered, the always-on part is powered in all states, the always-on part includes a power management unit to adjust the voltage of other components of the always-on system; a memory unit, which only stops power supply in the shutdown state Power supply in other states to keep data in the memory unit to provide data to other components of the always-on system; an input interface, powered only in the event detection state, receives at least one captured image from an image sensor, and sends out an The event detection state starts when a signal is triggered; an event monitor detects movement in the captured image, the event monitor is powered in the event detection state; a digital signal processor is powered only in the computer vision state , when movement is detected, image recognition is performed on the captured image; and an output interface is powered only in the computer vision state, so as to output the result of the digital signal processor. The always-on system with multi-layer power management of claim 1, wherein the always-on system is provided in a system-on-chip. The always-on system with multi-layer power management of claim 1, wherein the power management unit includes a low-dropout regulator. The always-on system with multi-layer power management of claim 1, wherein the always-on part further comprises: a timer that counts down from a preset time interval to issue a first trigger signal to indicate that the preset time interval has expired and enter the event detection state. The always-on system with multi-layer power management of claim 1, wherein the always-on part further comprises: a non-image sensing unit that detects an event notified by an external sensor, and sends out a second trigger signal, indicating a preset An event has occurred to start the event detection state. The always-on system with multi-layer power management of claim 5, wherein the external sensor comprises a passive infrared sensor, an ambient light sensor, a temperature sensor or a sound sensor. The always-on system with multi-layer power management of claim 5, wherein the event monitor is set in the image sensor, and when the event monitor detects motion, the event monitor notifies the non-image sensing unit to Start this computer vision state. The always-on system with multi-layer power management of claim 1, wherein the event detection state is divided into two sub-states: a triggering sub-state and a receiving sub-state, which are executed in sequence. The always-on system with multi-layer power management of claim 8, wherein the input interface outputs a clock signal and a control signal to the image sensor to activate the image sensor in the trigger sub-state. The always-on system with multi-layer power management as claimed in claim 1 further includes an oscillator for adjusting the input interface in the event detection state. The always-on system with multi-layer power management of claim 8, further comprising a data bus and an encoder for supplying power in the receiving sub-state, wherein the captured image is received by the data bus and by the encoder be encoded. The always-on system with multi-layer power management of claim 11, wherein the data bus and the encoder are powered only in the receiving sub-state. The always-on system with multi-layer power management of claim 11, wherein the data bus, the encoder and the event monitor are powered in the event detection state. The always-on system with multi-layer power management of claim 8, wherein the supply voltage of the memory cell in the receiving sub-state is greater than the supply voltage in the sleep state. The always-on system with multi-layer power management of claim 1, wherein the processing capability of the digital signal processor is greater than that of the event monitor. The always-on system with multi-layer power management of claim 1, wherein the result of the digital image processor is output through the output interface and stored in an external memory unit. The always-on system with multi-layer power management of claim 16, wherein the external memory unit stores a preset database for assisting the digital image processor to perform image recognition.

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