INTERFACE CONTROL

Description

FIELD OF THE INVENTION

[0001] Embodiments of the present invention relate to interface control. In particular, they relate to controlling current transitions on an electrical interface.

BACKGROUND TO THE INVENTION

[0002] A first electronic apparatus may be connected to a second electronic apparatus by an electrical interface, The first electronic apparatus may communicate information to the second electronic apparatus by driving current transitions on the electrical Interface. The information may, for example, be a clock signal, a control signal or data.

[0003] US 2008/0191766 discloses a slew rate detector that detects the slew rate of an input signal and provides it to a tail current control module. The tail current control module iteratively adjusts a tail current until the slew rate is within a predetermined range.

BRIEF DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

[0004] According to various, but not necessarily all, embodiments of the invention there is provided a method, comprising: using communication circuitry to drive, on a first occasion, a transition of an electrical parameter from a first value to a second value on an electrical interface; determining feedback information from the transition of the electrical parameter on the electrical interface on the first occasion; using the feedback information to determine how to change a power output of the communication circuitry in order to achieve, on a second occasion subsequent to the first occasion, a transition of the electrical parameter from the first value to the second value on the electrical interface within a threshold time period; and controlling the power output of the communication circuitry to achieve, on the second occasion, the transition of the electrical parameter from the first value to the second value on the electrical interface within the threshold time period.

[0005] The electrical parameter may be current or voltage.

[0006] The electrical interface may be between an apparatus and another apparatus and the feedback information may be dependent upon a property of the another apparatus. The property may relate to the physical characteristics of the another apparatus.

[0007] The feedback information may relate to a change of a voltage on the electrical interface. The change in voltage may occur during the first transition. The change of the voltage may be estimated to be linear.

[0008] The determined feedback information may indicate a time period over which a voltage on the electrical interface changed from a first voltage level to a second voltage level. Oscillation circuitry may determine the time period. The oscillation circuitry may be configured to generate pulses when the voltage on the electrical interface is between the first voltage level and the second voltage level.

[0009] Sequential first transitions may be used to sequentially communicate first information to the another apparatus,

[0010] Communication circuitry may be configured to drive, on a third occasion, a second transition of the electrical parameter on the electrical interface to the another apparatus. Determination circuitry may be configured to determine further feedback information dependent upon a further measured electrical parameter on the electrical interface. Control circuitry may be configured to use the determined further feedback information to control the power output of the communication circuitry to achieve, on the fourth occasion subsequent to the third occasion, the second transition of the electrical parameter on the electrical interface within a threshold time period.

[0011] The first transition may involve increasing current and the second transition may involve decreasing current. An electronic device may comprise the apparatus.

[0012] According to various, but not necessarily all, embodiments of the invention there is provided a computer program as claimed in claim 11.

[0013] According to various, but not necessarily all, embodiments of the invention there is provided an apparatus as claimed in claim 12.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For a better understanding of various examples of embodiments of the present invention reference will now be made by way of example only to the accompanying drawings in which:

Fig. 1

illustrates an electronic device;

Fig. 2

illustrates a method;

Fig. 3A

illustrates a change in voltage on an electrical interface;

Fig. 3B

illustrates two sequential pulses on an electrical interface;

Fig. 3C

illustrates four sequential pulses on an electrical interface;

Fig, 4

illustrates an example of determination circuitry; and

Fig 5

illustrates voltage-time diagrams for determination circuitry.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

[0015] The Figures illustrate an apparatus 10, comprising communication circuitry 16 configured to drive, on a first occasion, a first transition of a first electrical parameter on an electrical interface 18 to another apparatus 20; determination circuitry 12 configured to determine feedback information dependent upon a measured electrical parameter on the electrical interface 18; and control circuitry 14 configured to use the determined feedback information to control the power output of the communication circuitry 16 to achieve, on a second occasion subsequent to the first occasion, the first transition of the first electrical parameter on the electrical interface within a threshold time period.

[0016] Fig. 1 illustrates an example of an electronic device 50. The illustrated electronic device 50 comprises a first apparatus 10, an electrical interface 18 and a second apparatus 20. The electronic device 50 may, for example, be a hand portable electronic device such as a mobile telephone, a personal digital assistant or a personal music player.

[0017] The electronic device 50 illustrated in Fig. 1 comprises a housing that houses the first apparatus 10, the electrical interface 18 and the second apparatus 20. However, in alternative implementations of the invention, at least part of the electrical interface 18 and/or the second apparatus 20 may be situated outside the housing of the electronic device 50.

[0018] The electrical interface 18 may be any type of electrical interface. For example, it may comprise only a single electrical line or, alternatively, it may comprise a plurality of electrical lines. It may be a serial interface or a parallel interface. The electrical interface 18 may, for example, be implemented using a printed wiring board (PWB) or a cable. The interface 18 may be, for example, a memory interface, a Universal Serial Bus (USB), an IEEE 1394 interface, an I²C interface, a Secure Digital (SD) interface, a MultiMediaCard (MMC) interface or another type of interface.

[0019] The second apparatus 20 could have one or more of a variety of different functions. For example, in some implementations of the invention, the second apparatus is a memory device, such as an internal memory device or a user removable memory device. In other implementations, the second apparatus is an audio playback module, a wireless module such as a wireless receiver module, for example a Frequency Modulation (FM) radio module, or a Global Positioning System (GPS) module, or a wireless transceiver module, for example, a Bluetooth module, or a Wireless Local Area Network (WLAN) module or another type of module.

[0020] The first apparatus 10 comprises determination circuitry 12, control circuitry 14 and communication circuitry 16.

[0021] The communication circuitry 16 is configured to drive current or voltage transitions on the electrical interface 18, in order to communicate information to the second apparatus 20. The information may, for example, be a clock signal, a control signal or data.

[0022] In some embodiments of the invention, the communication circuitry 16 generates the information that it communicates on the electrical interface 16. For example, in this regard, the communication circuitry 16 may comprise a crystal oscillator that is used to drive periodic current or voltage transitions on the electrical interface 18.

[0023] In alternative embodiments of the invention, the information is generated by circuitry that is external to the communication circuitry 16. In these embodiments, the communication circuitry 16 receives the information from the external circuitry and drives current or voltage transitions on the electrical interface 18 in order to communicate the received information on the electrical interface 18. In this regard, the communication circuitry 16 may, for example, comprise an amplifier.

[0024] The determination circuitry 12 is configured to monitor the current or voltage of the electrical interface using a feedback signal 11. The determination circuitry 12 may monitor the current or voltage of one or more electrical lines of the electrical interface 18. The feedback signal 11 indicates to the determination circuitry 12 when a particular voltage has been reached on the electrical interface 18.

[0025] The determination circuitry 12 is configured to use feedback signal 11 to determine feedback information. For example, the feedback signal 11 may indicate to the determination circuitry 12 when a first current level I₁ or a first voltage level V₁ has been reached on the electrical interface 18, and when a second current level I₂ or a second voltage level V₂ has been reached on the electrical interface 18. The feedback information may, for example, be a time period between the first current/voltage level being reached on the electrical interface 18 and the second current/voltage level being reached on the electrical interface 18.

[0026] The control circuitry 14 is configured to use the determined feedback information to control the power output of the communication circuitry 16.

[0027] The first apparatus 10 may be implemented in a number of different ways. For example, the first apparatus 10 may comprise one or more application specific circuits (ASICs), field-programmable gate arrays (FPGAs), signal processing devices or other devices. For example, the ASIC(s) and/or FPGA(s) may be used to implement a state machine. Alternatively, the first apparatus 10 may be implemented using one or more software programmable processors.

[0028] Fig. 1 illustrates a computer-readable storage medium 24 that stores a computer program 22 which may control the operation of the first apparatus 10. The computer-readable storage medium 24 may, for example, be an article of manufacture that tangibly embodies the computer program 22 such as a memory device or a record medium such as a CD-ROM or DVD.

[0029] The computer program comprises instructions which, when executed by a processor, enable: driving, on a first occasion, a first transition of a first electrical parameter on an electrical interface 18; and controlling, using control circuitry 18, power output by using feedback information dependent upon a measured electrical parameter on the electrical interface 18 to achieve, on a second occasion subsequent to the first occasion, the first transition of the first electrical parameter on the electrical interface within a threshold time period.

[0030] The computer program instructions may control the operation of the first apparatus 10, when loaded into a processor. The computer program instructions may therefore provide the logic and routines that enable the first apparatus 10 to perform the method illustrated in Fig. 2. A processor, by reading a memory, is able to load and execute the computer program instructions.

[0031] Fig. 1 illustrates the operational coupling of blocks 12, 14, 16, 18 and 20. It should be appreciated that any number or combination of intervening elements can exist (including no intervening elements).

[0032] A method will now be described with regard to Figures 2, 3A and 3B. At block 100 of Fig. 2, the communication circuitry 16 drives a transition of a first electrical parameter on the electrical interface 18, in order to communicate information to the second apparatus 20. The first electrical parameter may, for example, be current or voltage. The transition may involve increasing or decreasing the amount of current/voltage on the electrical interface 18.

[0033] The second apparatus 20 is configured to read the information by detecting current or voltage levels on the electrical interface 18. The speed of the electrical interface 18 depends upon the rate at which current or voltage transitions on the electrical interface 18 can be made by the communication circuitry 16. The speed of the electrical interface 18 may also depend on requirements made in one or more standards.

[0034] The combination of the electrical interface 18 and the second apparatus 20 may be observed to have capacitance. The observed capacitance may vary, depending upon the physical characteristics of the second apparatus 20. For example, if the second apparatus 20 is a memory device, the capacity of the memory device may affect the capacitance that is observed. The higher the capacity of the memory device on the electrical interface 18, the higher the capacitance that is likely to be present.

[0035] The observed capacitance is also likely to be affected by the number of apparatuses that are connected to the electrical interface. The more apparatuses that are connected, the higher the observed capacitance is likely to be.

[0036] The length of the electrical interface 18 may also affect the observed capacitance. For example, if the electrical interface 18 is a cable (such as a USB or IEEE 1394 cable), the length of the cable may affect the observed capacitance. The longer the electrical interface 18 is, the higher the observed capacitance is likely to be.

[0037] The presence of the capacitance affects the speed that information can be communicated on the electrical interface 18. For example, when current is driven on the electrical interface 18, a charging effect occurs which slows down the rate of current/voltage increase on the electrical interface 18.

[0038] Fig. 3A schematically illustrates how the voltage on the electrical interface 18 changes when a default current is driven on the electrical interface 18. Once an increase in current is effected by the communication circuitry 16, the voltage on the electrical interface 18 increases from a minimum voltage level (V_min) to a maximum voltage level (V_max).

[0039] The voltage on the electrical interface 18, assuming a pure capacitance, is governed by the equation:

where: V is the voltage on the electrical interface 18, V_max is the maximum voltage on the electrical interface 18, t is time, R is the output resistance of the communication circuitry 16 and C is the observed capacitance.

[0040] It is possible to approximate equation (1) as

as illustrated in Fig 3A.

[0041] At block 200 of Fig. 2, the determination circuitry 12 determines feedback information using the feedback signal 11. That is, the determination circuitry 12 measures an electrical parameter on the electrical interface 18 and determines when the electrical parameter reaches a first level and when the electrical parameter reaches a second level. In this example, the determination circuitry 12 monitors a voltage on the electrical interface 18 to determine when a first voltage level V₁ has been reached and when a second, higher, voltage level V₂ has been reached. In an alternative example, the determination circuitry 12 may monitor a current on the electrical interface 18 to determine when a first current level I₁ has been reached and when a second, higher, current level I₂ has been reached.

[0042] The first and second voltages are intermediate the minimum voltage level (V_min) and the maximum voltage level (V_max). The first voltage level V₁ may be, for example, 10 to 20% of the maximum voltage level V_max. The second voltage level V₂ may be, for example, 80 to 90% of the maximum voltage level V_max.

[0043] A timer in the determination circuitry 12 determines the time taken for the voltage on the electrical interface 18 to increase from the first voltage level V₁ to the second voltage level V₂. The determination circuitry 12 then provides feedback information that indicates the determined time period Δt_i to the control circuitry 14.

[0044] It may desirable to achieve the voltage transition from the first voltage level V₁ to the second voltage level V₂ in a threshold time period Δt_f. Alternatively, the desired transition may be specified in terms of current. For example, it may be desirable to achieve a current transition from a first current value I₁ to a second current value I₂ within a threshold time period Δt_f, where I₁ is the current on the electrical interface when the voltage on the electrical interface 18 is the first voltage level V₁ and I₂ is the current on the electrical interface 18 when the voltage on the electrical interface is V₂.

[0045] For instance, a particular standard may dictate that a particular voltage transition or current transition has to be made within the threshold time period Δt_f, in order to meet the standard.

[0046] The control circuitry 14 compares the determined time period Δt_i with a threshold time period Δt_f. At block 300 of Fig. 2, the control circuitry 14 controls the power output of the communication circuitry 16. For example, if the determined time period Δt_i is greater than the threshold time period Δt_f, the control circuitry 14 increases the power output of the communication circuitry 16 so that the next time the communication circuitry 16 drives a voltage/current transition on the electrical interface 18, the voltage/current transition is achieved in the threshold time period Δt_f.

[0047] In more detail, the speed of the voltage transition on the electrical interface 18 from the first voltage level V₁ to the second voltage level V₂ can be expressed in terms of an "edge speed". The edge speed E is defined as:

where ΔV is V₂ - V₁, and Δt is the time taken to increase the voltage of the electrical interface 18 from the first voltage level V₁ to the second voltage level V₂.

[0048] If the change in voltage on the electrical interface 18 is estimated to be a straight line, then:

[0049] Where ΔI is the change in the current that is driven on the electrical interface 18 by the communication circuitry 16 in order to achieve a voltage transition from V₁ to V₂ on the electrical interface 18, C is the observed capacitance and E is the edge speed.

[0050] Assuming that ΔV remains constant, we can substitute equation (2) into equation (3) and show that:

[0051] Where ΔI_i is the default change in drive current by the communication circuitry 16 in order to achieve an initial predetermined voltage transition from V₁ to V₂, Δt_i is the time taken to achieve the initial predetermined voltage transition from V₁ to V₂, Δt_f is the threshold time period in which future voltage transitions from V₁ to V₂ are to be achieved and ΔI_f is the current change that is required to be driven by the communication circuitry 16 in order to achieve the voltage transition from V₁ to V₂ in the threshold time period Δt_f.

[0052] The values for the default drive current change ΔI_i and the threshold time period Δt_f are stored at the control circuitry 14. The value for the determined time period Δt_i is known because it was provided to the control circuitry 14 by the determination circuitry 12. The control circuitry 14 may use these values to determine the change in drive current ΔI_f required to achieve the voltage transition from V₁ to V₂ in the threshold time period Δt_f.

[0053] Once the required change in drive current ΔI_f has been determined by the control circuitry 14, the control circuitry 14 controls the power output of the communication circuitry 16 so that the next time the communication circuitry 16 drives a voltage/current transition on the electrical interface 18, the voltage/current transition is achieved in the threshold time period Δt_f.

[0054] Embodiments of the invention are not only applicable to increasing the power output of the communication circuitry 16. They may also be used to reduce the power output of the communication circuitry 16. If the control circuitry 14 determines that the drive current change ΔI_i caused a voltage/current transition to occur that was quicker than that which is desired/required, the control circuitry 14 may reduce the power output of the communication circuitry 16, so that ΔI_f < ΔI_i. This may decrease the power consumption of the first apparatus 10 and the amount of electromagnetic interference that is created when communicating on the electrical interface 18.

[0055] Advantageously, embodiments of the invention provide a method of optimizing the power output of communication circuitry 16 so that a current/voltage transition can be made on an electrical interface 18 within a desired/required time period, while minimizing power consumption and electromagnetic interference problems.

[0056] In the method described above, the second voltage level V₂ was described as being greater than the first voltage level V₁, meaning that the change in voltage defines a "rising edge". However, embodiments of the invention are equally applicable when the second voltage level V₂ is smaller than the first voltage level V₁, defining a "falling edge".

[0057] The time taken for a falling edge current/voltage transition to occur on the electrical interface 18 may not be the same as the time taken for a rising edge current/voltage transition on the electrical interface 18, even if the rising edge transition and the falling edge transition occur between the same values. Consequently, the magnitude of the change in power output of the communication circuitry 16 that is required to achieve a rising edge transition in a threshold time period may be different to that required to achieve a falling edge transition in a threshold time period.

[0058] Therefore, in some embodiments of the invention, the control circuitry 14 may control the communication circuitry 16 to change the power output for falling edge transitions by a different magnitude to that for rising edge transitions.

[0059] In other embodiments of the invention, the control circuitry 14 may determine the magnitude of the change in power output of the communication circuitry 16 that is required to achieve a rising edge transition in a threshold time period and the magnitude of the change in power output of the communication circuitry 16 that is required to achieve a falling edge transition in a threshold time period, and then use the higher magnitude of the two for both the rising and falling edge transitions.

[0060] It will be appreciated by those skilled in the art that a more accurate determination of the change in drive current that is required to achieve a current/voltage transition in a threshold time period can be made by using equation (1) rather than by modeling the transition from V_min to V_max (and vice-versa) as a straight line. However, while this method may be more accurate than that described above, more processing power will be required to implement it.

[0061] In some embodiments of the invention, the measured current/voltage transition on the electrical interface 18 is not made specifically for the purpose of determining how to change the power output of the communication circuitry 16. For example, the measured current/voltage transition may be used to communicate information (such a clock signal, a control signal or data) to the second apparatus 20 on the electrical interface 18 while remaining fully in accordance with one or more interface standards.

[0062] In other, alternative, embodiments of the invention, the measured current/voltage transition on the electrical interface 18 is made specifically for the purpose of determining how to change the power output of the communication circuitry 16 and is not used to communicate information to the second apparatus 20.

[0063] It should be appreciated that the time(s) at which the method described above (and illustrated in Fig. 2) is/are carried out may be different, depending upon how embodiments of the invention are implemented. For example, in some implementations, the method may only be carried out when the electronic device 50 is turned on or when the electrical interface 18 is first used by the first apparatus 10. In other implementations, the method may, for example, be carried out periodically. Alternatively, the method may, for example, be carried out each time an apparatus is connected to (or disconnected from) the first apparatus 10 via the electrical interface 18.

[0064] Fig. 3B illustrates a first pulse 302 and a second pulse 305. The first pulse 302 includes a rising edge 301 and a falling edge 303 that were produced prior to the power output of the communication circuitry 16 being changed by the control circuitry 14. The second pulse 305 was produced after the control circuitry 14 had used the feedback information relating to the rising edge 301 of the first pulse 302 and the feedback information relating to the falling edge 303 of the first pulse 302 to control the power output of the communication circuitry 16.

[0065] It can be seen from Fig. 3B that a technical effect of embodiments of the invention is that both the rising edge transition 304 from V_min to V_max and the falling edge transition from V_max to V_min 306 are quicker for the second pulse 305 than the corresponding transitions in the first pulse 302.

[0066] Fig. 3C illustrates four sequential pulses 306. 308, 310, 312 and relates to alternative embodiments of the invention where the power output of the communication circuitry 16 is incremented or decremented in an iterative manner. That is, feedback information may be determined on a number of occasions to iteratively change the power output of the communication circuitry 16.

[0067] In the Fig. 3C embodiments of the invention, the control circuitry 14 may not determine the change in drive current ΔI_f that is required to achieve a voltage/current transition on the electrical interface 18 within a threshold period of time. Instead, in response to receiving feedback information indicating that the time taken to perform a voltage/current transition is greater or smaller than a desired/required time period, the control circuitry 14 controls the communication circuitry 16 to increment or decrement its power output accordingly.

[0068] The control circuitry 14 continues to increment or decrement the power output of the communication circuitry 16 until the voltage/current transition is achieved in the required time period.

[0069] Fig. 4 illustrates one possible implementation of the determination circuitry 12. In this illustrative example, the determination circuitry 12 comprises voltage measurement circuitry 58, a controller 60, first and second drivers 62, 64, a capacitor 66 and a counter 72. The first and second drivers 62, 64 may, for example, be current drivers or amplifiers.

[0070] The voltage measurement circuitry 58 is configured to determine when the first voltage level V₁ and the second voltage level V₂ are reached on the electrical interface 18. When the voltage level reaches either V₁ or V₂, the voltage measurement circuitry 58 provides an output to the controller 60.

[0071] The controller 60 is configured to provide an output to the first driver 62. The output of the first driver 62 is connected to a capacitor 66 in parallel. The input of the second driver 64 is connected to the capacitor 66 in parallel. The second driver 64 is configured to provide two separate outputs to the controller 60 and an output to the counter 72.

[0072] Fig. 5 illustrates voltage-time diagrams 80, 82 and 84 for sections of the determination circuitry 12 that are indicated as "node 1", "node 2" and "node 3" in Fig. 4.

[0073] The first voltage-time diagram 80 indicates how the voltage at node 1 changes with time. The second voltage-time diagram 82 indicates how the voltage at node 2 changes with time. The third voltage-time diagram 84 indicates how the voltage changes at node 3 changes with time.

[0074] The controller 60, the first and the second drivers 62, 64 the capacitor 66 and the counter 72 can collectively be considered to be "oscillation circuitry". The oscillation circuitry generates pulses when the voltage on the electrical interface 18 is between the first voltage level V₁ and the second voltage level V₂.

[0075] In more detail, when the voltage measurement circuitry 58 measures that the voltage on the electrical interface has reached the first voltage level V₁, the voltage measurement circuitry 58 provides an output to the controller 60. In response to receiving the output, the controller 60 provides a logic HIGH output to the first driver 62. This logic HIGH signal is illustrated in the first voltage-time diagram 80 in Fig. 5.

[0076] In response to receiving the logic HIGH input, the first driver 62 provides an output current that causes the capacitor 66 to charge. There is a small delay between the first driver 62 receiving the logic HIGH signal from the controller 60 and the capacitor 66 beginning to charge. This is represented by "d₁" in the second voltage-time diagram 82. As the capacitor charges 66, the voltage at node 2 increases. When the voltage at node 2 reaches a voltage input high (VIH) threshold of the second driver 64, the second driver 64 provides a logic HIGH output. There is a small delay, indicated by "d₃" in the third voltage-time diagram 84, between the voltage reaching the VIH threshold and the second driver 64 providing the logic HIGH output.

[0077] When the voltage at node 2 reaches a voltage input low (VIL) threshold of the second driver 64, the second driver 64 ceases to provide the logic HIGH output. This results in a pulse being generated which is provided as an output to the counter 72. Reception of the pulse at the counter 72 causes the counter 72 to increment by 1. The generated pulse is also provided to the controller 60, on a first occasion, via a first signal line 70 and on a second occasion via a second signal line 72. When the first pulse on the first signal line 70 is received by the controller 60, the controller 60 ceases to provide the first driver 62 with a logic HIGH output. Consequently, the first driver 62 ceases to provide an output to charge the capacitor 66. The capacitor 66 then discharges via the first driver 62. This is illustrated in the second voltage-time diagram 82 as a drop in the voltage at node 2.

[0078] Subsequently, when the second pulse on the second signal line 72 is received by the controller 60, the controller 60 provides a logic HIGH signal to the first driver 62. After a small delay d₂,_,the first driver 62 begins to provide an output to charge the capacitor 66. A subsequent pulse is generated as an output from the second driver 64 through charging and discharging of the capacitor 66. This pulse causes the counter to again increment by one and initiates the process again via the controller 60.

[0079] The determination circuitry 12 illustrated in Fig. 4 uses the pulses generated as an output from the second driver 64 to count time. When the voltage of the electrical interface 18 reaches the second voltage level V₂, the voltage measurement circuitry 58 provides an output to the controller 60 and the controller 60 acts to prevent pulses oscillating around the oscillation circuit. The time period between the voltage on the electrical interface 18 reaching the first voltage level V₁ and the second voltage level V₂ is given by value on the counter 72 (i.e. the number of pulses received by the counter 72) multiplied by the time period T between corresponding edges (e.g. leading edges) of two pulses.

[0080] The implementation of the determination circuitry 12 illustrated in Fig. 4 advantageously counts time without any need for a crystal oscillator. It will be appreciated by those skilled in the art that the implementation of the determination circuitry 12 that is illustrated in Fig. 4 is only one of many implementations.

[0081] The blocks illustrated in Fig. 2 may represent steps in a method and/or sections of code in the computer program 22. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some steps to be omitted.

[0082] Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed. For example, the electrical interface 18 is described as being used to communicate information from the first apparatus 10 to the second apparatus 20. In practice, the electrical interface 18 may be bi-directional.

[0083] The embodiments described above assume that the determination circuitry 12 determines a "transition time" Δt_i between two predetermined voltages V₁ and V₂ and that a new drive current ΔI_f is determined via equation (4). However, in an alternative embodiment, the determination circuitry 12 may determine a "transition voltage" between an initial predetermined voltage and a variable final voltage within a predetermined time period.

[0084] The control circuitry 14 would calculate the new drive current using a ratio of a target voltage transition ΔV_f with the measured voltage transition ΔV_i. Using equations (2) and (3), it can be shown that:

[0085] It should also be appreciated that while embodiments of the invention have been described in relation to two apparatuses 10, 20 being connected to the electrical interface 18, in practice many more apparatuses may be connected to the electrical interface 18.

[0086] Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Claims

1. A method, comprising:

using communication circuitry (16) to drive, on a first occasion, a transition of an electrical parameter (I, V) from a first value (I₁, V₁) to a second value (I₂, V₂) on an electrical interface (18);

determining feedback information from the transition of the electrical parameter (I, V) on the electrical interface on the first occasion;

using the feedback information to determine how to change the power output of the communication circuitry (16) in order to achieve, on a second occasion subsequent to the first occasion, a transition of the electrical parameter from the first value to the second value on the electrical interface within a threshold time period (Δt_f); and

controlling the power output of the communication circuitry (16) to achieve, on the second occasion, the transition of the electrical parameter from the first value to the second value on the electrical interface within the threshold time period.

2. A method as claimed claim 1, wherein the electrical parameter is current or voltage.

3. A method as claimed in claim 1 or 2, wherein the electrical interface is between an apparatus and another apparatus, and the feedback information is dependent upon a property of the another apparatus.

4. A method as claimed in any of the preceding claims, wherein the feedback information relates to a change of a voltage on the electrical interface.

5. A method as claimed in claim 4, wherein the change in voltage occurs during the first transition.

6. A method as claimed in claim 4 or 5, wherein the change in voltage is estimated to be linear.

7. A method as claimed in claim 4, 5 or 6, wherein the first value is a first voltage level, the second value is a second voltage level, and the determined feedback information indicates a time period (Δt_i) over which a voltage on the electrical interface changed from the first voltage level to the second voltage level.

8. A method as claimed in claim 7, wherein the time period is determined using oscillation circuitry (60, 62, 64, 66, 72).

9. A method as claimed in claim 8, wherein the oscillation circuitry generates pulses when the voltage on the electrical interface is between the first voltage level and the second voltage level.

10. A computer program (22) comprising computer program instructions that, when executed by at least one processor, cause the method as claimed in one or more of the preceding claims to be performed.

11. An apparatus (10) comprising means for performing the method as claimed in one or more of claims 1 to 10.

12. A mobile telephone (50) comprising the apparatus of claim 11.

Ansprüche

1. Verfahren, umfassend:

Verwenden einer Übertragungsschaltung (16) zum Antreiben eines Übergangs eines elektrischen Parameters (I, V) von einem ersten Wert (I₁, V₁) zu einem zweiten Wert (I₂, V₂) an einer elektrischen Schnittstelle (18) zu einem ersten Zeitpunkt,

Bestimmen von Rückkopplungsinformationen vom Übergang des elektrischen Parameters (I, V) an der elektrischen Schnittstelle zum ersten Zeitpunkt,

Verwenden der Rückkopplungsinformationen, um zu bestimmen, wie die Leistungsabgabe der Übertragungsschaltung (16) zu ändern ist, um zu einem auf den ersten Zeitpunkt folgenden zweiten Zeitpunkt einen Übergang des elektrischen Parameters vom ersten Wert zum zweiten Wert an der elektrischen Schnittstelle innerhalb eines Schwellenzeitraums (Δt_f) zu erreichen, und

Steuern der Leistungsabgabe der Übertragungsschaltung (16), um zum zweiten Zeitpunkt den Übergang des elektrischen Parameters vom ersten Wert zum zweiten Wert an der elektrischen Schnittstelle innerhalb des Schwellenzeitraums zu erreichen.

2. Verfahren nach Anspruch 1, wobei es sich beim elektrischen Parameter um Stromstärke oder Spannung handelt.

3. Verfahren nach Anspruch 1 oder 2, wobei die elektrische Schnittstelle zwischen einer Vorrichtung und einer weiteren Vorrichtung besteht und die Rückkopplungsinformationen von einer Eigenschaft der weiteren Vorrichtung abhängen.

4. Verfahren nach einem der vorhergehenden Ansprüche, wobei die Rückkopplungsinformationen eine Spannungsänderung an der elektrischen Schnittstelle betreffen.

5. Verfahren nach Anspruch 4, wobei die Spannungsänderung während des ersten Übergangs auftritt.

6. Verfahren nach Anspruch 4 oder 5, wobei die Spannungsänderung als linear eingeschätzt wird.

7. Verfahren nach Anspruch 4, 5 oder 6, wobei es sich beim ersten Wert um einen ersten Spannungspegel und beim zweiten Wert um einen zweiten Spannungspegel handelt und die bestimmten Rückkopplungsinformationen einen Zeitraum (Δt_i) angeben, über den sich eine Spannung an der elektrischen Schnittstelle vom ersten Spannungspegel zum zweiten Spannungspegel geändert hat.

8. Verfahren nach Anspruch 7, wobei der Zeitraum unter Verwendung einer Oszillatorschaltung (60, 62, 64, 66, 72) bestimmt wird.

9. Verfahren nach Anspruch 8, wobei die Oszillatorschaltung Impulse erzeugt, wenn die Spannung an der elektrischen Schnittstelle zwischen dem ersten Spannungspegel und dem zweiten Spannungspegel liegt.

10. Computerprogramm (22), das Computerprogrammanweisungen umfasst, die bei Ausführung durch mindestens einen Prozessor die Durchführung des Verfahrens nach einem oder mehreren der vorhergehenden Ansprüche veranlassen.

11. Vorrichtung (10), die Mittel zum Durchführen des Verfahrens nach einem oder mehreren der Ansprüche 1 bis 10 umfasst.

12. Mobiltelefon (50), das die Vorrichtung nach Anspruch 11 umfasst.

Revendications

1. Procédé, comprenant les étapes consistant à :

utiliser un circuit de communication (16) pour commander, lors d'une première occasion, une transition d'un paramètre électrique (I, V) d'une première valeur (I₁, V₁) à une seconde valeur (I₂, V₂) sur une interface électrique (18) ;

déterminer des informations de rétroaction provenant de la transition du paramètre électrique (I, V) sur l'interface électrique lors de la première occasion ;

utiliser les informations de rétroaction pour déterminer la façon de changer la sortie de puissance du circuit de communication (16) afin d'obtenir, lors d'une seconde occasion ultérieure à la première occasion, une transition du paramètre électrique de la première valeur à la seconde valeur sur l'interface électrique au sein d'une période de temps de seuil (Δt_f) ; et

commander la sortie de puissance sur le circuit de communication (16) pour obtenir, lors de la seconde occasion, la transition du paramètre électrique de la première valeur à la seconde valeur sur l'interface électrique au sein de la période de temps de seuil.

2. Procédé selon la revendication 1, dans lequel le paramètre électrique constitue un courant ou une tension.

3. Procédé selon la revendication 1 ou 2, dans lequel l'interface électrique se situe entre un appareil et un autre appareil, et les informations de rétroaction dépendent de la propriété de l'autre appareil.

4. Procédé selon l'une quelconque des revendications précédentes, dans lequel les informations de rétroaction concernent un changement d'une tension sur l'interface électrique.

5. Procédé selon la revendication 4, dans lequel le changement de tension se produit pendant la première transition.

6. Procédé selon la revendication 4 ou 5, dans lequel on estime que le changement de tension est linéaire.

7. Procédé selon la revendication 4, 5 ou 6, dans lequel la première valeur constitue un premier niveau de tension, la seconde valeur constitue un second niveau de tension, et les informations de rétroaction déterminées indiquent une période de temps (Δt_j) au cours de laquelle une tension sur l'interface électrique est passée du premier niveau de tension au second niveau de tension.

8. Procédé selon la revendication 7, dans lequel on détermine que la période de temps utilise un circuit d'oscillation (60, 62, 64, 66, 72).

9. Procédé selon la revendication 8, dans lequel le circuit d'oscillation génère des impulsions lorsque la tension sur l'interface électrique se situe entre le premier niveau de tension et le second niveau de tension.

10. Programme informatique (22) comprenant des instructions de programme informatique qui, lorsqu'elles sont exécutées par au moins un processeur, amènent le procédé selon une ou plusieurs des revendications précédentes à être mis en oeuvre.

11. Appareil (10) comprenant un moyen de mettre en oeuvre le procédé selon une ou plusieurs des revendications 1 à 10.

12. Téléphone mobile (50) comprenant l'appareil selon la revendication 11.

Drawing