JPH04213929A - System and method for data transfer - Google Patents

Abstract

PURPOSE: To transfer data between remote points through physical barriers. CONSTITUTION: Plural states, which are determined by the position of a pedal, of a pedal switch 14 of an organ are sensed in a peripheral unit 12. Power to the peripheral unit physically separated from a host unit 16 is given through a primary winding 34 and a secondary winding 20 which ate magnetically coupled. A clock signal for the peripheral unit and a host unit is given by a power oscillator 30 which drives the primary coil or a tank coil of an oscillator in the host unit. Consequently, power and the clock signal are transmitted from the host unit to the peripheral unit through coupled windings, and data is sent back to the host unit through infrared radiation. Or data is sent back through coupled coils by loading the power oscillation circuit of the host unit during generation of data pulses in a data encoder 26 of the peripheral unit.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD This invention relates to data transfer systems between two physically separated locations, and more particularly to transformer windings inducing correspondingly encoded currents in magnetically connected windings. The present invention relates to a system for transferring data by encoding electrical currents.

0002

BACKGROUND OF THE INVENTION Preferred embodiments of the present invention seek to couple signals between a panel of foot pedals associated with a musical organ and a main or host processing unit that generates audio signals by selected foot pedals. It is something. However, the present invention is useful for coupling any peripheral to a main or central unit that performs some functions received from the peripheral units for the equipment between physically separate locations. It is for data transfer.

Traditionally, organ foot pedal panels are connected to the organ body by cables or other physical connections. More recently, reed switches have been installed in organ cabinets with magnets placed in foot pedals. When the pedal is pressed, the associated magnet activates the reed switch, thereby generating a corresponding signal to the main processing unit. When using magnets and reed switches, the pedal panel must be placed in close proximity to the organ body to ensure that the magnet activates the reed switch. There is little tolerance for misalignment between the two.

Various techniques have been developed for coupling physically separated locations without cables or other physical connections, such as the use of transformer coils and optoelectronic devices. Transformer coils are used to transfer power from one circuit to another, and then optoelectronic devices are used to transfer data. An example of such a system is the 1961
Steinman et al.
tal. No. 2,967,267 issued October 9, 1973 for "Reactive Interconnection of Modular Units" by Brobec
U.S. Pat. Issued US Patent No. 3
, 939,391, U.S. Pat. No. 4,737, issued April 12, 1988, to Banfalvi for "Single-Ended Self-Oscillating DC-DC Converter with Regulating and Blocking Control." , No. 898, 1988
Brown et al. on August 2, 2013.
"Transformer coupling for transmitting direct current through barriers"
U.S. Pat. No. 4,761,724 issued to NASA Technical Briefs,
As shown in the article "Contactless Coupling for Power and Data", September 1988, pages 22 and 24. These references generally disclose various ways in which transformers are used to transfer power.

[0005]

However, there is also typically a need to transfer data between distant locations and even through physical barriers. The NASA article refers to a system that uses coupled transformers for infrared data transmission and power transmission. Such systems require that optical paths exist between spaced apart locations such that infrared or equivalent optical coupling can occur.

It would be desirable to have a data and power connection that does not require optical paths and does not require precise coordination between the base unit and peripheral units. Furthermore, it is desirable that the data transmitted from the peripheral units be synchronized with the data processing of the base unit. Also, in such units, it is desirable that the clock frequency of the data stream is lower than the frequency that causes radio interference. This requires that the data transmission rate between the peripheral unit and the basic unit be lower than the typical frequency of the computer or central processing unit. Additionally, it is desirable to transfer data using sinusoidal waves rather than square waves to further reduce radio frequency interference emissions. Therefore, it is desirable to have a data transfer system in which data is sent to the CPU at a rate that is independent of the CPU's clock frequency.

[0007]

SUMMARY OF THE INVENTION The system of the present invention is a system for transferring data from a first location to a second location that is physically distant from the first location, the system comprising: a primary winding means; means connected to the winding means for applying an alternating current encoded using the predetermined data to the primary winding means; a secondary winding means which is suitably physically separated from the primary winding means for magnetically inducing a corresponding encoded alternating current; and a secondary winding means connected to the secondary winding means to induce the induced alternating current. and means for decoding data from.

In the above configuration, the alternating current has a predetermined frequency, the predetermined data is formed as a first data signal having a frequency proportional to the frequency of the alternating current, and the decoding means converts the induced alternating current into a first data signal. It is also possible to convert the first data signal into a second data signal having the frequency of the first data signal.

The first data signal is a first clock signal having pulses occurring at the same frequency as the alternating current frequency, and the decoding means is also capable of converting the induced alternating current into a second clock signal.

In the above configuration, the application means and the primary winding means are combined to include oscillation means adjusted to produce an alternating current having the same frequency as the frequency of the first clock signal. Good too.

In the above configuration, means for transmitting a second data signal having a frequency equal to the frequency of the second clock signal in response to the second clock signal; means for emitting a first clock signal having the same frequency as the frequency of the alternating current so that the second clock signal is synchronized with the second clock signal; The apparatus may further include means for detecting the second data signal.

In the above configuration, an element having at least two states is connected to the element and the transmission means, and the state of the element is periodically determined to generate a second data signal representing the current state of the element. means for detecting the transmitted second data signal and for comparing data representative of the current state of the element with a previous state of the element; and memory means for storing data, the comparing means being adapted to write only data representing a current state of the element that has changed from a previous state of the element into the memory means.

The above configuration further includes data processing means connected to the memory means for sampling the value of the data stored in the memory means at a frequency different from the frequency of the first clock signal. It can be done.

In the above configuration, the comparison means transmits state data indicating whether the data representing the state of the element stored in the memory means represents the current state of the element;
The data processing means may be responsive to the state data stored in the memory means and adapted to determine whether data representative of the state of the element stored in the memory means is to be received.

The means for transmitting the second data signal varies the magnitude of the induced alternating current in accordance with the second data signal, thereby causing a corresponding change in magnitude of the alternating current conducted to the primary winding means. The means for inducing and detecting the second data signal is further connected to the oscillating means for detecting the transmitted second data signal by detecting a change in magnitude of the alternating current conducted in the primary winding means. It may be done as shown.

Further, the system of the present invention is a system for transferring data from a first position to a second position physically distant from the first position, the system comprising a primary winding means and a connection to the primary winding means. means for applying an alternating current to the primary winding means; and means for magnetically inducing a corresponding alternating current from the primary winding means; The data signal is transmitted by changing the alternating current of one of the primary winding means and the secondary winding means which is to represent the data signal between the secondary winding means which are physically appropriately separated, and thereby the primary winding means. means for inducing a corresponding change in the alternating current flowing through the other of the wire means and the secondary winding means, and a change in the alternating current in the other winding means in response to a change in the alternating current in the other winding means; and means for generating a data signal representing the data signal.

In the above configuration, the applying means applies an alternating current having a predetermined frequency to induce an induced alternating current having the same frequency in the secondary winding means, and the transmitting means applies an alternating current having the same frequency to the secondary winding means. The generating means changes the magnitude of the alternating current at intervals corresponding to the frequency of the alternating current so that the generated data signal is synchronized with the transmitted data signal. It is possible to detect a change in the height.

[0018] The system of the present invention also provides at least two
A system for transferring data from an element having two states to a data processing means, comprising means for detecting a current state of the element; means for generating element data representative of a state; first memory means connected to the generating means for storing element data representative of a previous state of the element;
means connected to the generating means and the first memory means and for comparing element data representing the current state of the element with element data representing a previous state of the element; a second memory means for storing element data representing a state, and the comparison means writes into the second memory means only element data representing a current state of the element that has changed from a previous state of the element. be.

The above configuration further includes data processing means connected to the second memory means for sampling the element data stored in the second memory means at a frequency different from the first frequency. It can also be done.

The comparing means further writes state data in the second memory means indicating whether the element data stored in the second memory means represents the current element state, and the data processing means further writes state data stored in the second memory means. The element data stored in the second memory means may be responsive to the state data to determine whether element data stored in the second memory means is to be sampled.

In the above configuration, the data processing means writes response data indicating whether the data processing means has sampled the element data stored in the second memory means into the second memory means, and the comparison means writes response data indicating whether the data processing means has sampled the element data stored in the second memory means; The element data may be written to the second memory means only after the means have sampled the element data of the second memory means.

In the above configuration, in response to the response data, the comparison means writes state data to the second memory means indicating that the data processing means has sampled the element data stored in the second memory means. It can also be done.

The method of the invention is a method for transferring data from an element having at least two states to a data processing means, comprising: detecting the current state of the element; generating element data representing a previous state of the element at a first frequency; storing element data representing a previous state of the element in a first memory; and storing in the second memory means only element data representing a current state of the element that has changed from a previous state of the element.

The data processing means may further include sampling the element data stored in the second memory means at a frequency different from the first frequency.

Storing in the second memory means state data indicating whether the element data stored in the second memory means represents a current state of the element; The method may further include measuring state data stored in the method.

[0026] The step of transferring the element data to the second memory means further includes storing response data indicating whether the element data has been transmitted to the data processing means in the second memory means, and the step of transferring the element data to the second memory means includes It may also occur only after the response data indicates that it has been transmitted to the processing means.

[0027] The method may further include the step of storing, in the second memory means, status data indicating that the element data has been transferred to the data processing means.

[0028]

The present invention accomplishes the above objects and overcomes the limitations associated with the known prior art. In particular, the present invention provides a system for transferring data through a pair of physically separated induction windings using data encoded in an alternating current signal sent to one coil and induced in the other coil. provide. The encoded data can change the alternating current in either winding, so data can be transferred in one or both directions.

In one aspect of the invention, a system is provided for transferring data from a first location to a second location that is physically remote from the first location. A transformer primary winding and means for sending an alternating current encoded with predetermined data to the winding. The secondary winding may be disposed in correspondence with the primary winding, being suitably physically separated from the primary winding, and the primary winding transmits a corresponding alternating current encoded using predetermined data to the secondary winding. magnetically guided into the wire. Means connected to the secondary winding decode data from the induced alternating current.

The invention further provides a similar system having a primary winding and means connected to the primary winding for transmitting an alternating current to the primary winding. Similarly, the secondary winding may be disposed correspondingly to the primary winding, being suitably physically separated from the primary winding, and magnetically inducing a corresponding alternating current into the secondary winding. However, the system further includes means for transmitting the data signal by varying the alternating current in one of the primary and secondary windings representing the data signal. This change induces a corresponding change in the alternating current flowing through the other of the primary and secondary windings. Also, means responsive to changes in the alternating current in the other winding generates a data signal representative of changes in the alternating current in the other winding.

In yet another aspect of the invention, a system and associated method are provided for transferring data from an element having at least two states to a data processing unit. The system includes a detector for detecting the current state of the element. Means connected to the detector generate element data at a first frequency representative of the current state of the detected element. The memory stores element data representing the previous state of the element. The comparator compares the element's current state data with the element's previous state data. A latch only stores element data that represents the current state of the element that has changed from the element's previous state.

More specifically, a preferred embodiment of the invention provides a set of data generation switches associated with the organ foot pedals, the switches generating a data stream that generates an encoded data stream with synchronized pulses. The peripheral units are sequentially sensed by the encoder. Power and clock for the data encoder are routed through physically separate transformer primary and transformer secondary windings. The secondary winding is located in the peripheral unit and the primary winding is located in the host unit and the tank coil of the power oscillator.
coil). The alternating current signal conducted through the windings is used to obtain a clock signal for data processing.

Data is transmitted from the peripheral unit to the host unit by an optical device. The data stream is detected and transmitted to a synchronization detector that determines the start of the data stream. A bit counter stores the bit sequence and a data comparator determines whether each data bit is different from the bit's previously corresponding value. Afterwards, only changes in data are sent to the CPU via latches that store the number of bits and bit values. Control signals are used to allow the CPU to determine when to read the data stored in the latches. This allows C
The PU operates at a frequency that is independent of the data generation and operation frequencies of the peripheral and host units.

In other embodiments, data is also transmitted through magnetically coupled windings. In this embodiment, the generation of data pulses loads the secondary winding current. This load is reflected in the current drawn by the power oscillator driver. This varying current magnitude is decoded at the host unit to reconfigure the data stream for processing as described with reference to other embodiments. Data in the form of clock signals and status data is thus shown to be transferred in both directions via the magnetically coupled windings.

These and other features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments and accompanying drawings.

[0036]

[Example] First, in FIG. 1, the system according to the present invention has 10
This is summarized in . The system 10 includes a peripheral unit 12 that receives status data from a data source 14, such as a switch housed in a peripheral foot pedal unit and actuated by an organ foot pedal. These switches are also called two-state elements. The peripheral unit 12 is connected to a physically and electrically separate host unit 16. The host unit 16 is a microprocessor or central processing unit (CPU) 18
It is connected to the. Host unit 16 transfers power and clock to peripheral unit 12 and receives synchronization status data from peripheral unit 12 without interconnecting wiring. Additionally, host unit 16 also translates status data into processing data that is sent to host CPU 18.

The peripheral unit 12 includes a coil 20, which is a secondary winding of a power transformer, a clock receiver 22, and a power receiver 24. Both power and clock signals are derived from the current induced in coil 20. Data encoder 26 examines switch or element states from data source 14, power from power receiver 24, and clock signals from clock receiver 22. The data encoder sequences data bits representing the state of the switch and interleaves successive data bits with synchronization and control bits. The ordered data stream, also referred to as a second data signal, is output to a data oscillator 28. In this preferred embodiment, data transmission is by infrared radiation, as explained below with reference to FIG.

The host unit 16 has a power oscillator driver 32 and is equipped with a power oscillator 30 which is a means for delivering alternating current to the coil 34 . Coil 34 is a power and clock pickup coil 2 for peripheral unit 12.
It acts as a primary coil for 0. The coils are preferably formed on parallel planar circuit boards, with the coil axes preferably coaxial. This arrangement allows magnetic coupling to be formed even if the coils are somewhat misaligned. Coil 34 is also the tank coil of oscillator 30. The oscillator 30 is a free running type, and has a frequency of 20 to 4
Operates in the 0kHz range.

Clock driver 36 rectifies the alternating current signal produced by oscillator 30 and produces a clock signal that is synchronized with the clock signal produced by clock receiver 22. The preamplifier/detector 38 is connected to the data transmitter 2
Relay detected infrared radiation carrying data streams from 8 to 8. Detector 38 is means for detecting the second data signal.

The data is then transmitted to the sync detector 40. A synchronization detector 40 monitors incoming data, confirms the start of the data stream, and resets the count of a bit counter 42 when synchronization is detected. 1st memory 4
4 holds an image of the latest known state of the incoming bitstream. The data is input to a data comparator 46 which compares previous data from memory 44 with the incoming data. If the data is different, the data in memory 44 is replaced with the incoming data and the strobe on conductor 48 is activated. Furthermore, incoming data is ignored while the output strobe is active.

Strobe 48 is stored in the CPU interface, which functions as a second memory or latch 50. When the strobe becomes active, it interrupts the CPU 18. The CPU then reads the data output from bit counter 42 and detector 38 and stored in latch 50, as shown. When the CPU reads new data information, a response bit connected to data comparator 46 via conductor 52 is activated. When the comparator senses that the response input line is active, it resets the output strobe to become inactive. C
The PU will not read the data present in latch 50 as long as the strobe is inactive.

FIG. 2 shows the circuitry of peripheral unit 12 in more detail. The coil 20 is a clock receiver 22
and to a composite circuit forming power receiver 24 . The alternating current present in coil 20 is rectified by rectifier 54, filtered by filter 56, and maintained at a level of 12 volts by Zener diode D2. Energy is stored in capacitor C1. The clock is formed from the alternating current signal by a rectifier consisting of diodes D4 and D16, which signal is sent to a counter U3 forming part of the data encoder 26. The power generated and held in capacitor C1 is used to power the data encoder 26 and data oscillator 28 components.

The encoder 26 includes a pair of matrix switches U1 and U2. The three least significant bits from counter U3 are sent to the enable input of switch U1. The three more significant bits of counter U3 are sent to the enable input of switch U2. Thereby, the 8x8 switch matrix whose X terminal is connected to the XN terminal of U1 can be regarded as each row of the switch matrix. Correspondingly, the terminals X of the switch U2 are selectively connected to eight XM terminals, forming what can be considered as an array of switch matrices. Therefore, for each input of the enable input to the switch,
One of the terminals is connected to switch U2 via pedal switch 14.
is connected to one of the XM terminals of the As shown in FIG. 3, the right end of switch SW1 is connected to one of the rows associated with switch U1, and the cathode of diode D3 is connected to switch U2.
connected to the column defined by . As the clock count progresses in counter U3, each X of switch U1
The N terminal is selectively connected to each XM terminal of switch U2.

The two X terminals to switches U1 and U2 are connected through a data output circuit 28. The data transmission circuit 28 includes a drive transistor Q1 and a light emitting diode (LED) D for data transmission to the host unit 16.
1.

The switch matrix is a total 8x8 matrix to generate a 64-bit data stream. However, data encoder 26 encodes data using synchronous control pulses that limit the number of data bits available to the foot pedal switch. As shown in FIG. 2, the X0 terminal of switch U2 is grounded. When this terminal is selected by the appropriate set of enable inputs, all eight corresponding terminals of switch U1 are held low. This is 8 consecutive Lo
Forming what is called a sync pulse formed from the w pulse. This is used to confirm the start of the data stream.

Further, the terminal X7 of the switch U1 is connected to the terminals X1 to X of the switch U2 via the diodes D5 to D11.
7. When selected by the matrix switch, these diodes are always conducting. These connections do not sense the state of the pedal switch as the other terminal connections do. Therefore, each eighth bit of the data stream is always High. This ensures that the only period during which the eight pulses are low is the period of the sync pulse. Therefore, 15 bits of the 64-bit data stream are used for control and are not available to carry pedal switch status data. In such a configuration, up to 49 pedal switches can be sensed. It will be appreciated that other switch configurations may be used with fewer or more pedal switches being sensitive.

This data stream obtained is represented by the upper signal in FIG. The clock signal input to counter U3 is represented by the lower signal. Note that each data stream begins with eight low sync pulses. The synchronization pulse is followed by seven sets of eight data pulses. The first seven of each set of eight data pulses represent pedal switch status data. The eighth pulse is always a high pulse and does not represent switch data. Upon completion of each 64-bit data stream, the next set of sync pulses indicates the next stream of data pulses. These synchronization pulses and high bit pulses are used to indicate the validity of the data being transmitted from peripheral unit 12 to host unit 16.

FIG. 4 shows the configuration of the circuit associated with the host unit 16 in more detail. Infrared data transmitted by data transmitter 28 in peripheral unit 12 is received and sensed by optical receiver 38. This receiver detects and amplifies the data stream and
It is transmitted to a synchronization detector 40 and a data comparator 46. The data sent to the synchronization detector is first sent to the logic block U5A.
and an inverter represented by U6C. The output of this inverter is connected to the reset of the low bit counter U2. Counter U2 is clock driver 36
It also receives a clock signal from

The clock signal is derived from an alternating current fed to the transformer primary winding 34 forming the tank coil for the oscillator 30. Oscillator driver 32 is transistor Q
1 and an emitter resistor R2. The current conducted by the transistor varies depending on the load on the coil 34.

When counter U2 counts eight consecutive low bits (synchronization pulses), bit counter 42, shown as unit U4, is reset and counts the number of clock pulses. This count is the latch 5
0 indicates the number of bits of the data stream associated with the data on line D7 input. The bit count associated with that data is represented on input terminals D0-D6.

The values of the previous data stream are stored in memory U1, which is a 64-bit shift register. For each clock pulse, each successive value of previous data is output to a data comparator 46 which also receives new data. Comparator 46 comprises an exclusive OR gate that produces a high output only if there is a difference between the old and new data. The output of this comparator is input to flip-flop U3A. This flip-flop generates a strobe on conductor 48 which is stored in latch 50, as previously described. This strobe is CPU18
This is an interruption to. This interrupt is sent to terminals D0 to D6.
The position value stored above (position val
ue) indicates to the CPU that the data value stored at terminal 7 is new.

Preferably, the CPU operates at a frequency much greater than the frequency of the clock signal derived from the sine wave generated by the oscillator 30. The values are held in latches 50 until CPU 18 reads them. Once the value is read, a response signal, shown as "Get" in FIG. 4, is input from the CPU to latch 50. This signal is used to reset flip-flop U3A, which subsequently resets the strobe signal and makes it inactive.

When the value of the strobe is changed to indicate that the data on D7 is new data, the inverse of the strobe is output from the flip-flop and the ``acquire'' signal (
is logically ORed with (U5D) and inverted again (U6B
), sent to the mode control pin of U1. New data is prevented from entering memory (old data is recycled into memory) from the time the signal is activated until the ``acquire'' signal becomes active and inactive again.

Therefore, the comparator 46 serves only to compare old and new data, and does not directly affect data recirculation. The recirculation path occurs as described above and is connected to pin 1 of U1.
0 (mode control pin) becomes active (High)
. Old data returns from pin 6 of U1 to pin 1 of U1 (
recirculating input). Register U1 is an image of the data in CPU 18 and is therefore a separate memory independent of the CPU clock. Therefore, it can be seen that there is no timing relationship between the CPU and the circuitry of the host unit 16. Furthermore, since only the processing data is transmitted to the CPU,
Data transfers are typically irregularly timed.

In the embodiments described with reference to FIGS. 1 to 4, data in the form of a clock signal is transferred from the primary winding 34 to the secondary winding 20. Since the oscillator 30 is oscillated at the desired clock rate, the alternating current signal is rectified and used as a clock signal for both the components in the peripheral unit and the components in the host unit. This allows data transmission and reception to be synchronous. Therefore, both power and clock signals are transmitted through the wound coil.

[0056] For efficient data transmission, the infrared emitter and receiver must be placed closer together than the coil. This requirement may also be overcome by transmitting data from the peripheral unit to the host unit through the windings. In this way, no optical path between the two units is required. This allows opaque materials such as wood to be placed between the units, allowing conductor-free data and power transmission.

This configuration is possible by modifying the circuit shown in FIG. In this embodiment, the peripheral units are identical except that diode D1 is not a light emitting diode. Depending on the nature of its operation, encoder 26 receives load down or power depending on the high and low levels of the data bits being formed in the data stream. This produces a current in coil 20 that varies according to the data stream. This change in received power is reflected in the primary coil 34 accordingly. The current delivered by the oscillator reflects the load applied to the oscillator. The data stream is thus represented by the change in oscillator current. The data detection circuit 58 shown in FIG. 5 is used to detect changes in the oscillator current. In this case, instead of using data transmitter 28, power receiver 24 and coil 20 become the data transmitter.

In the embodiment shown in FIG. 5, the oscillator alternating current signal is input to a clock generator 60, which is very similar to the clock driver 36 shown in the host unit 16. Emitter resistance R of power oscillator driver 32
The aforementioned signal representing the current of 2 is applied to the amplification or gain block 6
2 is input. This amplified signal is input to comparator 64 to reset the logic level of the data stream. These data logic levels are then transferred to the data conditioning circuit 6.
6 to generate a data stream equivalent to the data stream output from preamplifier/detector 38 in the embodiment of system 10. Detection circuit 58 can be thought of as providing a means for generating a data signal representative of changes in oscillator current. Therefore, both the clock and data streams are provided from the alternating current applied to the primary winding 34. These signals are then used in an embodiment that is otherwise similar to that described for the host unit 16 according to FIG. Data is processed in the same way and sent to the CPU in a similar manner. Therefore, apart from the aforementioned differences, these embodiments are identical.

The invention, as explained with reference to FIG. It can be seen that the loads provided provide power and clock signal transmission through the transformer windings.

The present invention provides a connectorless peripheral unit that is easy to move and eliminates the drawbacks due to the presence of physical connectors or cables. Transferring power and data between peripheral and host units in accordance with either embodiment reduces physical placement problems that often occur in other methods. The physical layout requirements associated with the embodiment of FIG. 5 are less stringent than those of the embodiments illustrated by FIGS. 2 and 3, since no infrared transmission coupling is provided. In the embodiment of FIG. 5, an opaque material can be inserted between the two units while providing power, clock and state data information transfer.

By using the power oscillator also as the data clock, both units can have a common clock, resulting in synchronous data transfer without the need for additional communication channels. Therefore, the power oscillator is 2
plays an important role. In the embodiment of FIG. 5, it plays a triple role by providing data transfer from the peripheral unit to the base unit or host unit.

High confidence in the data integrity of continuous state data is maintained by testing for the presence of synchronization bits. Loss of synchronization would indicate peripheral removal or failure. Transferring continuous state data from the peripheral unit to the host unit instead of processing data has the advantage of simplifying data encoding and decoding. Furthermore, the transfer of processing data to the CPU reduces CPU usage time because only state changes require CPU processing.

Using a free-running oscillator instead of a CPU-generated oscillator further simplifies the circuit configuration for generating the sine wave, thereby reducing RFI emissions. Depending on the self-running oscillator, the status information may be sent to the CPU.
The oscillator can operate at any convenient frequency. The frequency of the oscillator is chosen to be low enough to prevent radio interference, but high enough to maximize the efficiency of the type of coil used and high enough to allow timely use of the input data.

It will further be appreciated that changes in circuitry and detail may be made without departing from the spirit and scope of the invention as defined in the claims. Thus, while particular embodiments have been described, it will be apparent to those skilled in the art that variations may be made in the embodiments while practicing the invention. For example, much of the logic and data processing can also be easily provided using microprocessors or the like. Accordingly, these components and specific circuit configurations are merely exemplary. Those skilled in the art will recognize other equivalent and obvious circuits that may be used to implement the invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a system according to the invention.

FIG. 2 is a circuit schematic diagram showing peripheral units included in the system of FIG. 1;

FIG. 3 is a diagram of a pedal switch using the circuit of FIG. 2 to generate state data.

FIG. 4 is a schematic diagram of the host circuitry outlined in FIG. 1;

FIG. 5 is a block diagram illustrating another embodiment for data transmission between the peripheral unit and host unit of FIG. 1;

FIG. 6 illustrates data streams and clock signals generated at the peripheral unit and received for synchronous sampling at the host unit in both embodiments.

[Explanation of symbols]

12 Peripheral unit 14 Organ pedal switch 16 Host unit 18 CPU 20 Secondary winding 26 Data encoder 30 Power oscillator 34 Coil

Claims (21)

[Claims] 1. A system for transferring data from a first location to a second location that is physically distant from the first location, the system comprising:
primary winding means; means connected to the primary winding means for applying an alternating current encoded using predetermined data to the primary winding means; and a secondary winding means connected to the secondary winding means, the means being physically suitably spaced from the primary winding means for magnetically inducing a corresponding alternating current encoded with predetermined data. means for decoding data from the induced alternating current;
A data transfer system equipped with 2. The system of claim 1, wherein the alternating current has a predetermined frequency, the predetermined data is formed as a first data signal having a frequency proportional to the frequency of the alternating current, and the decoding means comprises: A system for converting an induced alternating current into a second data signal having a frequency of the first data signal. 3. The system according to claim 1, wherein the first
The system wherein the data signal is a first clock signal having pulses occurring at the same frequency as the alternating current frequency, and the decoding means converts the induced alternating current into a second clock signal. 4. The system of claim 3, wherein the applying means and the primary winding means are arranged in combination to produce an alternating current having a frequency that is the same as the frequency of the first clock signal. A system equipped with. 5. The system according to claim 4, wherein the second
means for transmitting a second data signal having a frequency equal to the frequency of the second clock signal in response to the clock signal; and connected to the oscillator means so that the first clock signal and the second clock signal are synchronous. means for emitting a first clock signal having the same frequency as the frequency of the alternating current;
means for detecting a transmitted second data signal at intervals corresponding to the first clock signal in response to the clock signal;
A system that also includes: 6. The system according to claim 5, wherein an element having at least two states is connected to the element and the transmission means, and the system periodically determines the state of the element to represent the current state of the element. and means for detecting the transmitted second data signal, and means for comparing data representative of the current state of the element with a previous state of the element, and connected to the comparing means. and a memory means for storing data representing a state of the element, wherein the comparing means writes into the memory means only data representing a current state of the element that has changed from a previous state of the element. 7. The system of claim 6, wherein the system is connected to the memory means and includes data processing for sampling data values stored within the memory means at a frequency different from the frequency of the first clock signal. further equipped with means,
system. 8. The system according to claim 7, wherein the comparison means transmits state data indicating whether the data representing the state of the element stored in the memory means represents the current state of the element. , a data processing means responsive to state data stored in the memory means and determining whether to receive data representative of a state of the element stored in the memory means. 9. The system according to claim 5, wherein the second
The means for transmitting the data signal changes the magnitude of the induced alternating current in accordance with the second data signal, thereby inducing a corresponding change in magnitude of the alternating current conducted in the primary winding means, and The means for detecting the data signal is further connected to the oscillator means for detecting the transmitted second data signal by detecting a change in magnitude of the alternating current conducted in the primary winding means. . 10. A system for transmitting data from a first location to a second location physically distant from the first location, the system comprising: primary winding means; means for applying an alternating current; and disposed relative to the primary winding means, the primary winding means being suitably physically separated from the primary winding means for magnetically inducing a corresponding alternating current; transmitting the data signal by changing the alternating current in one of the primary winding means and the secondary winding means to represent the data signal; means for inducing a corresponding change in the alternating current flowing through the other of the means and responsive to the change in the alternating current in the other winding means to generate a data signal representative of the change in the alternating current in the other winding means; A data transfer system comprising means for and. 11. The system according to claim 10,
The applying means induces an induced alternating current of the same frequency in the secondary winding means by applying an alternating current having a predetermined frequency, and the transmitting means is responsive to the alternating current and is equal to the frequency of the alternating current. A system in which the magnitude of the alternating current is changed depending on the frequency, and the generating means detects changes in the magnitude of the alternating current at intervals corresponding to the frequency of the alternating current so that the generated data signal is synchronized with the transmitted data signal. 12. A system for transferring data from an element having at least two states to data processing means, comprising: means for detecting a current state of the element; means for generating element data representing a current state of the detected element; first memory means connected to the generating means for storing element data representing a previous state of the element; 1 means connected to the memory means and for comparing element data representing the current state of the element with element data representing a previous state of the element; and an element connected to the comparison means and the data processing means and representing the state of the element. second memory means for storing data, wherein the comparing means writes only element data representing a current state of the element that has changed from a previous state of the element to the second memory means. 13. The system according to claim 12,
further comprising data processing means connected to the second memory means for sampling the element data stored in the second memory means at a frequency different from the first frequency;
system. 14. The system according to claim 12,
The comparing means further writes state data in the second memory means indicating whether the element data stored in the second memory means represents the current element state, and the data processing means further writes state data in the second memory means indicating whether the element data stored in the second memory means represents the current state of the element. and determining whether to sample element data stored in the second memory means. 15. The system according to claim 14,
The data processing means writes response data indicating whether the data processing means has sampled the element data stored in the second memory means into the second memory means, and the comparison means writes response data indicating whether the data processing means samples the element data stored in the second memory means; A system for writing element data into the second memory means only after sampling. 16. The system according to claim 15,
In response to the response data, the comparing means writes status data to the second memory means indicating that the data processing means has sampled the element data stored in the second memory means. 17. A method for transferring data from an element having at least two states to a data processing means, comprising: detecting a current state of the element; element data representing the current state of the detected element; generating at a first frequency, storing element data representing a previous state of the element in the first memory, and combining the element data representing a current state of the element with the stored element data representing a previous state of the element. A method of data transfer comprising: comparing; and storing in second memory means only element data representative of a current state of the element that has changed from a previous state of the element. 18. The method of claim 17 further comprising sampling, by the data processing means, the element data stored in the second memory means at a frequency different from the first frequency. 19. The method according to claim 17, comprising:
storing in the memory means state data indicating whether the element data stored in the second memory means represents a current state of the element;
The method further comprising measuring state data stored in the memory means. 20. The method according to claim 19, comprising:
The step of transferring the element data to the second memory means further includes storing response data in the memory means indicating whether the element data has been transmitted to the data processing means; A method that occurs only after the response data indicates that it has been transmitted. 21. The method according to claim 20, comprising:
The method further comprises the step of storing status data in the memory means indicating that the element data has been transferred to the data processing means.