Wii Mote Materials And Design Methodology Information Technology Essay

The Wii is a home video game console released by Nintendo. As a seventh generation console, the Wii primarily competes with Microsofts Xbox 360 and Sony’s PlayStation 3. Nintendo states that its console targets a broader demographic than that of the two others. As of March 2010, the Wii leads the generation over the PlayStation 3 and Xbox 360 in worldwide sales and in December 2009 broke the record for best-selling console in a single month in the United States.

A distinguishing feature of the console is its wireless controller, the Wii Remote, which can be used as a handheld pointing device and detects movement in three dimensions. Another distinctive feature of the console is WiiConnect24, which enables it to receive messages and updates over the Internet while in standby mode.

The Wii is Nintendo’s fifth home console, the direct successor to the Nintendo GameCube, and able to play all official GameCube games. Nintendo first spoke of the console at the 2004 press conference and later unveiled the system at the 2005. Nintendo CEO Satoru Iwata revealed a prototype of the controller at the September 2005 at Tokyo Game Show. At 2006, the console won the first of several awards. By December 8, 2006, it had completed its launch in four key markets.

The company has given many reasons for this choice of name since the announcement however, the best known is:

Wii sounds like ‘we’, which emphasizes that the console is for everyone. Wii can easily be remembered by people around the world, no matter what language they speak. No confusion and no need to abbreviate.

NEMS (Nano Electro Mechanical Systems) is being pitched as the eventual successor to the MEMS (Micro Electro Mechanical Systems) motion sensing tech used by Nintendo in Wii MotionPlus. The latest NEMS breakthrough comes courtesy of a bunch of researchers at TU Delft in The Netherlands, who “have succeeded in measuring the influence of a single electron on a vibrating carbon nanotube.”

Wii Remote

The Wii Remote is the primary controller for the console. It uses a combination of built in accelerometers and infrared detection to sense its position in 3D space when pointed at the LEDs within the Sensor Bar. This design allows users to control the game using physical gestures as well as traditional button presses. The controller connects to the console using Bluetooth and features rumble as well as an internal speaker. The Wii Remote can connect to expansion devices through a proprietary port at the base of the controller. The Wii Motion Plus was announced as a device that connects to the Wii Remote to supplement the accelerometer and Sensor Bar capabilities and enable actions to be rendered identically on the screen in real time. Nintendo also revealed the Wii Vitality Sensor, a fingertip pulse oximeter sensor that connects through the Wii Remote.Nintendo-Wii.jpg

Ultra-sensitive motion gaming

The scientists, from the Kavli Institute for Nanoscience at TU Delft, have published their latest findings in the journal Science. The experiments in the project took place in a cooled environment close to absolute zero and involved a “suspended vibrating carbon nanotube, comparable to an ultra small violin string” which starts to vibrate at a certain frequency as a result of a surrounding alternating electric field.

“The number of electrons allowed on the nanotube causes very slight changes in the vibration behavior of the tube. Thus the frequency at which the nanotube vibrates shifts very slightly each time an electron is added. The scientists have succeeded in charting the influence of the presence of just a single electron.

The research is vital to the development of NEMS (Nano Electro Mechanical Systems) such as ultra small switches and measuring instruments, with applications of the technology including ultra sensitive motion controllers for games companies.

Testing Accelerometer

The test device is surface micromachine, force balanced three axis accelerometer with integrated CMOS circuitry. Each of the three accelerometers comprises a proof mass, proof mass suspension, capacitive pickoff mechanism, electronic servo loop, and signal digitizer. Each of the three proof masses is constrained to move in a single dimension orthogonal to the other two thus providing the input accelerations sensing along three mutually orthogonal axes, X, Y and Z.

The X and Y axis accelerometers were implemented using a comb structure in which the fingers of a compliant comb are interdigital with fixed comb fingers to provide an output differential signal from the capacitive coupling between individual fingers. The Y axis comb structure is about half the mass of the X axis. The Z axis accelerometer is implemented differently with a hinged plate as a proof mass. The proof mass forms a capacitor with the ground plane polysilicon structure of the device. A fixed reference capacitor plate was designed into the Z axis channel to provide a differential output in conjunction with the moveable plate. The accelerometer die is shown below.untitled.bmp

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The electrical output of an accelerometer channel is a pulse train. The acceleration sensed by the device is contained in the pulse density of the output pulses. By design an output or bias frequency is present even at zero input acceleration. The scale factor or density of output pulses per unit time per unit acceleration input is a function of the device clock frequency. Stability of the clock for the accelerometer directly affects accelerometer performance therefore maintaining good clock stability is essential for measuring accelerometer capability.

Theoretical and Computational of Wiimote Accelerometer and Gyroscopic

Accelerometers are manufactured using a relatively new technology called MEMS Technology also known as MicroElectroMechanical System. In the image below you can see a micro machined MEMS three axis accelerometer under a microscope. The average human hair is about 80 micrometers in diameter and you can see that this accelerometer is roughly 200 micrometers wide or three hair widths. The four maze looking parts in the corners are actually springs and as the device is moved the centre part of the accelerometer moves, expanding and compressing these springs. Meanwhile, electricity is flowing through these springs and as the springs expands or compresses the spacing changes, this in turn changes the capacitance which is an electrical property that can then be detected and outputted on the wires you see coming out of the chip. The device is quite fragile so a micro machined cover is placed over the accelerometer.

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Figure 1: This micromechanical structure is the core of a 3 axis MEMS accelerometer. Such an open microstructure is very delicate, susceptible to degradation by dust, water, and almost any physical contact. Special tooling must be used to dice and package the chip, and hermetic packaging is required to ensure long-term reliability.

Accelerometers use to pointing, senses orientation, vibration and shock. Meanwhile, it can accurately sense three axes of acceleration: up and down, left and right, forward and backward.

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Photo 2: Motion or controller

The hardware that most people do not realize that there is actually a small infrared camera on the end of the Wiimote. The camera is locate as shown in the picture below,

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Photo 3: Sensor in Wiimote

The sensor bar is really not a “sensor” but in fact two infrared LED lights. When you point the Wiimote at your TV the infrared sensitive camera picks up the lights and uses this data to determine where you are pointing the Wiimote, rather than using the accelerometers. The reason for this is because accelerometers are good at detecting motion in the X, Y, and Z directions but they cannot detect rotational acceleration (as when you rotate the remote to move the cursor around on the screen). In order to detect rotational accelerations you need what is called a gyroscope (also based on MEMS technology).

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Gyroscopes are devices that measures or maintain an orientation of an object using the principle of angular momentum. Unfortunately gyroscopes are pretty expensive so engineers at Nintendo came up with the sensor bar idea to reduce the price of the controllers to an affordable level.

Fabrication of Wiimote

The Wii Remote is the Wii’s main input device. It is a wireless device, using standard bluetooth technology to communicate with the Wii. It is built around a Broadcom BCM2042 bluetooth System-on-a-chip, and contains multiple peripherals that provide data to it, as well as an expansion port for external add-ons.

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Broadcom BCM2042

The Wii remote uses the standard bluetooth HID protocol to communicate with the host, which is directly based upon the USB HID standard. As such, it will appear as a standard input device to any bluetooth host. However, the Wii Remote does not make use of the standard data types and HID descriptor, and only describes its report format length, leaving the actual content undefined, which makes it useless with standard HID drivers. The Wii Remote actually uses a fairly complex set of operations, transmitted through HID Output reports, and returns a number of different data packets through its Input reports, which contain the data from its peripherals.

Memory and Registers

The Wii Remote includes a built-in EEPROM memory, part of which is accessible to the user to store that. This user part is used to store calibration constants, as well as the Mii Data. Additionally, many peripherals on the Wii Remote have registers which are accessible through a portion of the address space.

EEPROM memory

There is a 128kbit EEPROM chip in the Wii Remote. Parts of its contents include code for the built in microcontroller, and a generic section which can be freely read and written by the host. This section is 0x1700 bytes long, and part of this memory is used to store the Mii Data. It can be accessed by reading or writing to addresses 0x0000-0x16FF in the Wii Remote’s virtual memory space, in the actual EEPROM chip, the data is located at 0x0070-0x176F.

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EEPROM chip

The BCM2042 microcontroller built into the Wii Remote includes a large 108kb on-chip ROM section for storing firmware. If the EEPROM chip really contains code for the BCM2042 then this was probably done to make firmware updates possible, so there might be a way of accessing the other parts of the EEPROM via bluetooth as well.

Input Features

The Wii Remote has two input features that are controlled directly by the broadcom chip, a Three Axis Accelerometer and 11 Buttons. Additionally, it has an IR camera with an object tracking processor, and an expansion port that allows for external input features such as those contained in the nunchuk and the classic controller.

Accelerometer

The Wii Remote includes a three axis linear accelerometer located on the top suface of the circuit board, slightly left of the large A button. The integrated circuit is the ADXL330, manufactured by Analog Devices. This device is physically rated to measure accelerations over a range of at least +/- 3g with 10% sensitivity.

Since the accelerometer is measures the force exerted by a set of small proof masses inside of it with respect to its enclosure, the accelerometer measures linear acceleration in a free fall frame of reference. If the Wii remote is in free fall, it will report zero acceleration. At rest, it will report an upward acceleration (+Z, when horizontal) equal to the acceleration due to gravity, g (approximately 9.8 m/s²) but in the opposite direction. This fact can be used to derive tilt from the acceleration outputs when the Wii Remote is reasonably still.

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ADXL330 Accelerometer

Buttons

The Wii Remote has 11 buttons on its front face, and one trigger style button on the back. Of these, the Power button is special and is treated differently by the Wii Remote. All the other buttons are independently accessible through a two byte bitmask which is transmitted first in most Input reports. A button will report a 1 bit if pressed or a 0 bit otherwise.

IR Camera

The Wii Remote includes a 128×96 monochrome camera with built in image processing. The camera looks through an infrared pass filter in the remote’s plastic casing. The camera’s built in image processing is capable of tracking up to 4 moving objects, and these data are the only data available to the host. Raw pixel data is not available to the host, so the camera cannot be used to take a conventional picture. The built in processor uses 8x subpixel analysis to provide 1024×768 resolutions for the tracked points. The sensor bar that comes with the Wii includes two IR LED clusters at each end, which are tracked by the Wii Remote to provide pointing information. The distance between the centers of the LED clusters is 20 cm .

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128×96 monochrome camera

Feedback Features

The Wii Remote sports three feedback features which are Player LEDs, Rumble, and the Speaker.

Player LEDs

There are four blue LEDs on the front face of the Wii remote. During discovery and before initialization, these LEDs blink at a fixed rate. The number of blinking LEDs is proportional to the battery voltage, indicating battery charge.

During game play with the Wii, one LED is lit to indicate the player number assigned to the Wii remote. However, the LEDs are independently controllable by the host, and can be set to display any pattern. They can also be modulated at a moderately high speed, enabling some brightness control at the cost of a lot of bluetooth bandwidth. Sigma delta modulation works reasonably well for this.

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Wii Remote Player LEDs

Speaker

The Wii Remote has a small low-quality 21mm piezo-electric speaker, used for short sound effects during gameplay. The sound is streamed directly from the host, and the speaker has some adjustable parameters. The speaker is controlled by using three output reports, together with a section of the register address space of the Wii Remote.

Rumble

The Wii remote includes a rumble feature, which is implemented as a small motor attached to an off center weight. It will cause the controller to vibrate when activated. The rumble motor can be turned on or off through any of the output reports. Setting the LSB (bit 0) of the first byte of any output report will activate the rumble motor, and unsetting it will deactivate it.

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However, this will also have the side effect of turning off all LEDs. Since there is no output report that only affects the rumble motor, and all of them do affect it, an implementation might need to store both the rumble and LED values locally and use the same Output Report for both. Another possibility would be using the status request report (0x15). The rumble bit needs to be set properly with every single report sent, to avoid inadvertently turning the rumble motor off.

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Wii Remote Rumble

Wii Mote Materials and Design Methodology

One of the main features of Wii mote is its motion sensing capabilities, which allow the user to interact with and manipulate items on the screen via gesture recognition and pointing with the help of a few sensors materials which are optical sensors technology and MEMS sensors technology.

By using MEMS Accelerometer, it able to provide three axis motion signal processing, the accelerometer is used to sense motion of the user in three dimensions of freedom, which are forward backward, left right, and up down, when the Wii mote is picked up and manipulated, it provides a quick element of interaction, sensing motion, depth and positioning dictated by the acceleration of the Wii-mote itself.

Besides the accelerometer, there is another MEMS sensor used in Wii mote is the MEMS Gyroscope used to detect rotational accelerations which combined with accelerometer and result out highly accurate representation of the Wii mote in three dimension space, which allow real 1:1 three dimension control.

A gyroscope is a basic inertial sensor, which can measure an external angular rate. The MEMS gyroscope is an inertial angular rate sensor fabricated using MEMS technology. When an external angular rate is applied to the MEMS gyroscope, the proof mass vibrating at resonant frequency is forced to vibrate in orthogonal direction due to the Coriolis force. The angular rate can be estimated by measuring the amplitude of the orthogonal oscillation.

The Wii mote is a breakthrough design remote control unlike the traditional gamepad controllers of the previous consoles as Wii mote design for single handed remote controller. This was done to make motion sensitivity more intuitive, as a remote design is fitted perfectly for pointing, and in part to help the console appeal to a broader audience that includes non-gamers. The body of the Wii mote measures 148 mm (5.83 in) long, 36.2 mm (1.43 in) wide, and 30.8 mm (1.21 in) thick. The Wii mote model number is RVL-003, a reference to the project codename “Revolution”. The controller communicates wirelessly with the console via short range bluetooth radio, with which it is possible to operate up to four controllers as far as 10 meters away from the console.

However, to utilize pointer functionality, the Wii mote must be used within five meters (approx. 16 ft) of the Sensor Bar. The controller’s symmetrical design allows it to be used in either hand. Wii mote design used the Analog Devices’s model ADXL330 MEMS accelerometer sensor in it, as Mr Genyo Takeda, Senior Managing Director/General Manager, Integrated Research & Development Division, Nintendo Co., Ltd. Said “We selected the ADXL330 because its accuracy, small size, and extremely low power consumption were critical to the Wii Console’s design objectives and key for a wireless controller that will revolutionize the gaming industry.” Nintendo relied on their experience with Analog Devices’ iMEMS Motion Signal Processingâ„¢ technology. Mr Genyo Takeda also mention that “For the industry’s first mainstream game controller using MEMS acceleration sensors, we turned to Analog Devices, an industry leader whose acceleration sensors are used by Nintendo”

The ADXL330 three axis accelerometer sensors is a small, thin, low power, complete 3 axis accelerometer with signal conditioned voltage outputs, all on a single monolithic IC. The product measures acceleration with a minimum full scale range of ±3g. It can measure the static acceleration of gravity in tilt sensing applications, as well as dynamic acceleration resulting from motion, shock, or vibration. The ADXL330 is available in a small, low profile, 4 mm Ã- 4 mm Ã- 1.45 mm, and 16 lead.16 pin 01.jpg

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Figure 1 Functional Block Diagram of ADXL330

The ADXL330 provided three sense axes in a 4 mm Ã- 4 mm Ã- 1.45 mm LFCSP package. An X-ray of the ADXL330 package, which contains a single integrated chip, is presented in Figure 2. Figure 3 shows that the ADX330 MEMS sensor was fabricated as a single chip, with the MEMS structure in the centre of the die, beneath a hermetic cap, and the ASIC circuitry around the outside edge. The ASIC circuitry uses a single metal, single poly 3 µm BiCMOS process, while the MEMS is fabricated using three layers of polysilicon, with the top 4 µm thick poly 3 being used to form the MEMS structures, as shown in Figure 4. Figure 5 show the ADXL330 Die.

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Figure 2 ADXL330 Package X-Ray

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Figure 3 Decapsulated ADXL330 Chip Figure 4 ADXL330 MEMS Structures

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Figure 5 ADXL330 MEMS Die

Wii mote design also used inven sense IDG-650 Integrated dual axis MEMS Gyroscope sensor to enhance its response accuracy.  The accelerometer is only capable of measuring movement velocity along the X, Y, and Z axis only linear acceleration without rotation. The problem is that acceleration due to gravity can easily be confused with linear motion when using the device.

And though the accelerometer can track gravity, it cannot measure horizontal rotation. This results in a jittery representation of the interpreted data which, when combined with subtle hand movements, makes for an oft-inaccurate picture of what is going on with the remote. Gyroscopes, on the other hand, measure rotation directly. These sensors are very responsive and do not amplify hand jitter, but cannot respond to the linear movement that accelerometers specialize in. When a gyroscope and an accelerometer are combined, the pair of sensors affords the ability for highly accurate representation of the control device in three dimensional spaces. Mr Genyo Takeda, General Manager of Nintendo’s Integrated research and development Division said “Nintendo selected the IDG-650 for its ability to measure large dynamic motions, high shock resistance, and accuracy for sensing the fast moving arm and hand motions required to support exciting new game titles.”

The IDG-650 is the world’s first integrated dual axis MEMS rate gyroscope designed for high performance game controllers and A/V remote controllers which require wide dynamic range motion processing, high impact shock resistance and low cost. An innovative vibrating dual mass in plane sensing configuration senses the rate of rotation about the X and Y axis, resulting in a highly integrated dual axis gyro with guaranteed by design vibration rejection and high cross axis isolation. The IDG 650 also includes an integrated AutoZero feature for minimizing bias drift over temperature.

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Figure 6 A diagram of the IDG-650, the InvenSense chip on Wii-mote

Aspects of Accelerometer and Gyroscopic

Accelerometer are utilized in the field of various engineering application such as automotive industry, robot system, electronics appliances and toys due to their small size, low prize and high performance. Meanwhile it can include a sensor to sense the movement and proof mass. The electric capacity type accelerometer can have an advantage in require less power and space and it have high sensitivity. Of course it also have it weakness which is they are affected by electromagnetic interference and parasitic of electromagnetic.

Gyroscopic are use to control apparatus and systems. It can produce torque that will influences behavior of an object. One of the advantages is in connection with controlling the attitude of satellites or vehicles operating in outer space. However, there have a weakness it may encounter which is due to the presence of undesired counter-acting torques resulting when gyroscopic attempts to produce torque

Process Integration & Simulation

What is process integration? Process Integration has the objective of the design and optimization of integrated chemical manufacturing systems.  Process Integration starts with the selection of a series of processing steps and there interconnection to form a manufacturing system to transform raw materials into desired products.

Simulation is the imitation of some real thing, state of affairs, or process. The act of simulating something generally entails representing certain key characteristics or behaviours of a selected physical or abstract system.

Process Integration of NMEMS Accelerometer

MEMS technology and the drive for cost reductions continue to evolve. Examples of cost reduction include die size reduction, yield improvement, and integration. The accelerometer contains an interface IC and transducer die packaged in a Small Outline Integrated Circuit (SOIC) 16 lead package. The g-cell transducer is constructed using surface micromachining techniques.

The signal conditioning of the accelerometer channel begins with a capacitance-to-voltage conversion followed by a 2 stage switched capacitor amplifier. The 2 stage amplifier has adjustable offset and gain trimming. The accelerometer device has a 4 pole, low-pass, switched capacitor Bessel filter with options for a cut-off frequency of 400 to 700 Hz. The output of the filter is amplified by the output stage, which buffers the signal to the external Vout pin and contains the temperature compensation for sensitivity. The EPROM trim state is valid from 4.4 to 5.5 V with 4.75 to 5.25 V considered the normal operation range for VDD. A self-test voltage can be applied to the electrostatic deflection plate in the transducer resulting in a known output. The product has several fault checks for low voltage detection (LVD), clock and/or bias monitoring, and a check of the stored even parity of the EPROM trim register.

Process Integration of NMEMS Gyroscopic

Companies like InvenSense of Santa Clara have devoted themselves entirely to fabricating dual-axis gyroscopes that integrate with handheld devices. InvenSense is working with their patented manufacturing system, to integrate two very low-cost X-axis and Y-axis MEMS gyroscopes in order to not only simplify but also reduce costs associated with the production process typically needed for gyroscopes of any kind. Company leaders have transferred much of their production energy to a high-output MEMS foundry that can create thousands of MEMS gyroscope sensors alongside other essential consumer electronics devices, all on the surface of a single 6-inch silicon wafer.

Their research and development teams are hard at work on continually shrinking the size of this wafer as well as integrating applications and functions performed by electronics hardware so that every day one device can be used to do the work of two, thereby taking up less space on the chip and reducing the eventual size of the end product. And as we all know, if there’s anything consumers typically want out of their handheld electronics, it tends to be a consistently smaller and sleeker design that still delivers an increase in functionality.

They can combine these gyroscopes on a single chip, making it easier for the main electronics manufacturer to then install the technology into their devices.

A single wafer bonding process utilizes existing aluminium from standard CMOS to achieve a hermetic seal on thousands of devices while simultaneously providing hundreds of thousands of electrical interconnects between the MEMS sensing electrodes and CMOS electronics (see photo).http://invensense.com/images/technology_clip_image002_0004

This creates cost and performance advantages for InvenSense versus its competition. Alternative approaches are more costly and inefficient, including the addition of a silicon cap with a glass-frit seal, residual gas getters for vacuum reliability, hermetically sealed ceramic packages, and multi-chip assembly of the MEMS and CMOS at the package level. Furthermore, additional cost advantages are derived from the simple 6-mask bulk silicon Nasiri-Fabrication process, which enables high-speed calibration and electrically integrated MEMS system-level testing.

Another key enabling technological advantage for InvenSense is its patented, out-of-plane resonating structures, which are the cornerstone of a vibrating, dual-mass, tuning fork design that surpasses the competition by its ability to serve the low-cost consumer electronics market.

Vibratory mass gyros are based on the transfer of energy between the two resonating modes of a structure due to Coriolis acceleration, which arises in a rotating reference frame, and is proportional to the rate of rotation. Vibratory mass gyros generally contain a pair of vibrating masses that are driven to oscillation with equal magnitude and in opposite directions. When the gyro device is rotated, the Coriolis force creates an orthogonal vibration force proportional to the rate of rotation, which is measured using capacitive sensing techniques.

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Conclusion

The Nintendo Wii have revolutionized the way we know gaming but now it seems they are taking the same to the next level. Now how about a mind controlled game that Nintendo is proposing? T3 gives a little clue that all you have is a headset accessory that uses brainwaves to control characters and features immersing in ear headphones. So just imagine a streamlined Wii emote with just one button, which you point and press and rest your brain takes over. Though brain-wave technology has already become a reality with Emotive pioneering in game systems, but soon it seems Nintendo will come out with the first mind-controlled console on the market.futuristic nintendo wii 2010

Future Work

Future work with the WiiMote will include methods for user control via the various inputs on the WiiMote. These inputs could be used to better define a fall and allow the user to put the device into sleep mode in order to conserve batteries while sleeping or resting in a stationary position and to ensure that their inactivity is not considered as a fall. Other devices will be explored for integration with the WiiMote to provide a more robust solution by monitoring additional parameters such as heart rate, voice or sound and etc. Additionally, the threshold values in the detection algorithm will be made dynamic or adaptive in order to be more effective for different subjects with different levels of mobility. Furthermore, the calibration routine will be automated by estimating the offset value during use.

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