This application claims the benefits of the Taiwan Patent Application Ser. No. 101111317. filed on Mar. 30, 2012, the subject matter of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to the technical field of data transmission and, more particularly, to a multiplexed audio cable joystick and system thereof.
2. Description of Related Art
Current consumer electronics are typically provided with a touchpad as one of the input devices. To meet with the requirements of being light, thin, short, and small, a touchpad and a panel are combined into a touch panel for a user to conveniently input data,
However, the touchpad may not be suitable for an input on a consumer electronic product, particularly for a rapid and accurate input. Therefore, when currently marketing iOS devices, such as iPad, iPhone available from Apple, are used by a user to play video games, an external joystick is typically added.
Another solution is to use a wireless joystick, such as a Bluetooth joystick. However, a Bluetooth chip is expensive and requires the initialization before being used, i.e., without the plug and play function, which is inconvenient in use.
As the smart phones and tablet computers become more and more popular, it is urgently necessary to have a joystick to connect with them. Therefore, it is desirable to provide an improved multiplexed audio cable joystick and system thereof to mitigate and/or obviate the aforementioned problems.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a multiplexed audio cable joystick and system thereof, in which an audio cable is used to transmit pressed key information, so as to obtain the joystick at low cost and practice.
According to a feature of the invention, a multiplexed audio cable joystick is provided, which includes a plurality of keys, a key scanner, a frame format encoder, a transmission modulator, and a digital to analog converter (DAC), The key scanner is connected to the keys in order to scan a state of the keys to be pressed to thereby output corresponding pressed key information. The frame format encoder is connected to the key scanner in order to generate a frame transmission data according to the pressed key information, The transmission modulator is connected to the frame format encoder in order to perform a carrier modulation on the frame transmission data o thereby generate a modulated transmission data. The DAC is connected to the transmission modulator in order to convert the modulated transmission data into an analog audio data, wherein the transmission modulator has a same frequency band as an audio signal spectrum, and the frequency band has a plurality of sub-bands, such that the transmission modulator modulates the frame transmission data to one of the sub-bands for transmitting data multiplexing.
According to another feature of the invention, a multiplexed audio cable joystick system is provided, which includes a first multiplexed audio cable joystick, a second multiplexed audio cable joystick, a Y-type audio connection line, and a portable electronic device. The first multiplexed audio cable joystick has a plurality of first keys in order to modulate pressed key information of the first keys to a first sub-band of an audio signal spectrum for converting into a first analog signal. The second multiplexed audio cable joystick has a plurality of second keys in order to modulate pressed key information of the second keys to a second sub-band of the audio signal spectrum for being converted into a second analog signal. The Y-type audio connection line is connected to the first multiplexed audio cable joystick and the second multiplexed audio cable joystick in order to mix the first analog signal and the second analog signal to thereby generate an analog mixing signal, wherein the analog mixing signal has the first and second analog signals. The portable electronic device has a headphone jack connected to the Y-type audio connection line in order to receive and decode the first analog signal and the second analog signal to thereby generate the first pressed key information of the first multiplexed audio cable joystick and the second pressed key information of the second multiplexed audio cable joystick.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The keys 410 are used as an input of the joystick 400, and have several directional keys, a firing key, and a continuous firing key.
The key scanner 420 is connected to the keys 410 in order to scan a state of the keys 410 to be pressed to thereby output corresponding pressed key information. The pressed key information can be represented by 16 bits, each corresponding to a key for indicating whether the key is pressed or not.
For example, the four directional keys of
The frame format encoder 430 is connected to the key scanner 420 in order to generate a frame transmission data according to the pressed key information.
The header field has, for example, 20 bits to store an identifier of a special pattern to help the decoder with a simple recognition and further a synchronous decoding.
The variable header field has, for example, 2 bits to recognize a joystick 400 when more than one joysticks are existed, wherein “00” indicates the first joystick, “01” indicates the second joystick, and so
The data field has, for example, 16 bits to record the 16-bit pressed key information.
The check field has, for example, 10 bits to check whether the data is correct or not. The content of the check field is generated by performing a cyclic redundancy check (CRC) process on the variable header field and the data field.
The transmission modulator 440 is connected to the frame format encoder 430 in order to perform a carrier modulation on the frame transmission data to thereby generate a modulated transmission data.
The transmission modulator 440 has the same frequency band as the audio signal spectrum. The frequency band has a plurality of sub-bands, such that the transmission modulator modulates the frame transmission data into one of the sub-bands for transmitting data in multiplexing.
The transmission modulator 440 includes a quadrature phase shift keying (QPSK) modulation device 441, an inverse fast Fourier transform (IFFT) device 443, and a cyclic prefix and guard interval device 445.
The QPSK modulation device 441 is connected to the frame format encoder 430 in order to perform a quadrature phase shift keying on the frame transmission data to thereby output multiple phases (i.e., generating a multi-phase output). Since the frame transmission data is of 48 bits, the QPSK modulation device 441 can output 24 phases after the quadrature phase shift keying is performed on the frame transmission data.
The IFFT device 443 is connected to the QPSK modulation device 441 in order to perform an inverse fast Fourier transform on the phases to thereby generate a multi-carrier modulation signal.
The IFFT device 443 is a 128-dot IFFT device to carry out the multi-carrier modulation, and in this case a 128-dot multi-carrier modulation signal is generated after the inverse fast Fourier transform is performed on the phases. Further, each joystick 400 is set to a different sub-band that is used by its corresponding IFFT device. For example, in this embodiment, the 128-dot IFFT device is used to perform the multi-carrier modulation, where the 6-29 carriers are of the first sub-band (corresponding to the first joystick 400), and the 33-56 carriers are of the second sub-band (corresponding to the second joystick 400).
When more joysticks 440 are used, the carrier sub-bands can be reallocated to the joysticks respectively, or a 256-dot IFFT device is used to increase the number of carriers. This can be accomplished by those skilled in the art, and thus a detailed description is deemed unnecessary.
The cyclic prefix and guard interval device 445 is connected to the IFFT device 443 in order to add a cyclic prefix as a guard interval in the multi-carrier modulation signal to thereby generate the modulated transmission data. In this case, the cyclic prefix and guard interval device 445 adds a 72-dot guard interval in the 128-dot multi-carrier modulation signal to thereby generate a 200-dot modulated transmission data.
The DAC 450 is connected to the transmission modulator 440 in order to convert the modulated transmission data into an analog audio data. The IFFT device 443 of each joystick 400 uses a different sub-band to perform the multi-carrier modulation, such that the transmission modulator of the joystick can modulate the frame transmission data to the different sEib-band to thereby obtain a frequency division multiplexing (FDM) communication transmission. Further, the DAC 450 has a sampling rate of 16 KHz, i.e., the 200-dot modulated transmission data. The DAC 450 with the 1.6 KHz sampling rate outputs the audio signal to thereby obtain that the key data transmission time of the joystick 400 is 0.0125 sec. (200/16 KHz), i.e., the key update frequency thereof is 80 Hz (16 KHz/200). Such an 80 Hz key update frequency is higher than the fresh frequency (60 Hz) of a typical liquid crystal screen, so it can be used in a portable device with a liquid crystal screen, and the speed can meet with the user requirement.
The first multiplexed audio cable joystick 401 has a plurality of first keys 410 in order to modulate pressed key information of the first keys to a first sub-band of an audio signal spectrum for being converted into a first analog signal of the first sub-band, wherein the first sub-band is in a relatively low frequency band of the audio signal spectrum.
The second multiplexed audio cable joystick 402 has a plurality of second keys 410 in order to modulate the pressed key information of the second keys to a second sub-band of the audio signal spectrum for being converted to a second analog signal of the second sub-band, wherein the second sub-band is in a relatively high frequency band of the audio signal spectrum.
The Y-type audio connection line 610 is connected to the first multiplexed audio cable joystick 401 and the second multiplexed audio cable joystick 402 in order to mix the first analog signal and the second analog signal to thereby generate an analog mixing signal for output. Namely, the Y-type audio connection line 610 outputs the analog mixing signal which contains the first and second analog signals in mixing.
The portable electronic device 620 has a headphone jack 621 connected to the Y-type audio connection line in order to receive and decode the first analog signal and the second analog signal to thereby generate the first pressed key information of the first multiplexed. audio cable joystick and the second pressed key information of the second multiplexed audio cable joystick.
The ADC 622 is connected to the headphone jack 621 in order to receive the analog mixing signal for being converted into a digital mixing signal.
The ADC 622 uses a sampling rate of 16 KHz. Namely, the ADC 622 can sample the audio signal at the input end of the headphone jack 621 in real time.
The cyclic prefix and guard interval removal device 623 is connected to the ADC 622 in order to remove the 72-dot guard interval signal, which is possibly polluted by an inter-symbol interference, so as to output the pure 128-dot digital mixing signal which the guard interval is removed.
The EFT device 624 is connected to the cyclic prefix and guard interval removal device 623 in order to perform fast Fourier transform on the pure 128-dot digital mixing signal to thereby generate the phase and amplitude of a 128-dot FFT modulation signal.
The QPSK demodulation device 625 is connected to the FFT device 624 in order to perform a QPSK demodulation on the phase and amplitude of the 128-dot FFT modulation signal to thereby generate a first frame transmission data corresponding to the first sub-band and a second first frame transmission data corresponding to the second sub-band.
The frame format decoder 626 is connected to the QPSK demodulation device 625 in order to perform a frame format decoding on the first and the second frame transmission data to thereby generate the first pressed key information corresponding to the first multiplexed audio cable joystick and the second pressed key information corresponding to the second multiplexed audio cable joystick.
As cited, the portable electronic device 620 can receive the pressed key information respectively sent by the first and the second multiplexed audio cable joysticks 401 and 402.
The invention can use the headphone jack of an iOS device (iPhone, iPad, iPod Touch, or the like) as a transmission interface to replace a USB, UART, Bluetooth, touch panel or the like as the input interface of a joystick.
With an increase of the number of joysticks, a higher PSK (such as 8 PSK: octal phase shift keying or 16 PSK: hexadecimal phase shift keying) and a multi-carrier modulation with more carriers can be used to carry more bit message in an analog audio signal and to transmit the key state to the iOS device through an audio cable in real time.
When the number of keys of the joystick is largely increased and the key arrangement is changed, the invention can change the joystick into a keyboard. Namely, the invention can simply develop the joystick as the input keyboard of the iOS device through an audio cable.
As cited, the iOS device uses a touch panel for interaction in the prior art, which may suffer an inconvenient operation in using the touch panel. In this case, the invention uses the audio cable in transmission to thus obtain the low-cost and practical joystick, so as to overcome the currently marketing problems.
Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.
Number | Date | Country | Kind |
---|---|---|---|
101111317 | Mar 2012 | TW | national |