MXPA02011875A - Method and apparatus for remote control transmission. - Google Patents

Abstract

A remote control is operative to transmit a remote control signal composed of a first portion and a second portion. The first and second portions are typically a pulse and a space. The pulse has a pulse width of a given duration within a pulse width range, while the space has a space width of a given duration within a space width range. An interrupt signal provided to indicate the end of transmission of the remote control signal is disabled when a space portion requires a space width greater than the space width range. The interrupt signal signaling the end of the remote control transmission is then disabled for a predetermined period of time essentially equivalent to a length of time that the additional space exceeds the space width. During the predetermined period of time, the remote control thus transmits a space. The interrupt signal is then re-enabled after expiration of the predetermined period of time in order to allow for another remote control transmission.

Description

METHOD AND APPARATUS FOR REMOTE CONTROL TRANSMISSION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to remote controls for electronic devices, and in a more particular way, to remote control transmissions. 2. Description of Related Art In modern consumer electronic devices, such as television receivers, top boxes (e.g., cable boxes, satellite receivers, stereos, etc., and the like (collectively, consumer electronic devices), many functions and / or features can be accessed and / or controlled by means of a remote control device.The remote control device can be operated by the user, as in the case of a manual remote control, or it can be operated by a remote control. device, in the case of a remote control type "relay." In both cases, the remote control generates and transmits (in a wireless way) a remote control signal that is received by the receiving electronic device. The signal • Control is encoded in a manner appropriate to the receiving device. The receiving device receives the coded control signal, and carries out the requested command.

The remote control can use a variety of wireless transmission means, in order to send or transmit the control signal generated from the remote control to the receiving electronic device. A type of remote control uses bursts of infrared (IR) light or radiation as the medium / vehicle for the transmission of encoded signals, which are received by a suitable receiver device associated with the consumer's electronic device. The consumer electronic device may include a microprocessor to perform many functions of the receiver in addition to decoding the received infrared encoded command signals, and generating the appropriate control signals in response to the same. An infrared encoded command signal generally consists of a binary data stream of a given word length, wherein the presence of a burst of infrared energy represents a binary 1, and the absence of infrared energy represents a binary 0. Infrared transmissions from a remote control are usually made up of a series of pulses (high voltage / 1 binary) and spaces (low voltage / binary 0) of different lengths. Different combinations of impulses and spaces are used to create unique infrared codes. Each unique infrared code represents a different key in the remote control. The devices Consumer electronics may or may not use the same codes for the same or similar characteristics. Accordingly, a remote control for an electronic device may not necessarily work with another electronic device. A typical remote control includes a transmitter circuit that can be part of an integrated circuit (IC), and more particularly, an application-specific integrated circuit (ASIC). For typical transmissions using the infrared circuit, the length of the pulse and the length of the space are individually specified in separate recorders. The recorders are loaded with a pulse / space combination when a key is pressed on the remote control. When an infrared sequence is being transmitted, an interruption is generated at the end of each impulse-space combination. At the time of the interruption, the next sequence or combination of impulse-space is loaded from the user's registers to the transmission recorders. At this time, it is safe for the remote to reload the pulse registers and user spaces, so that they are established for the next pulse-space combination, which is loaded at the next interrupt. A problem with the typical remote control circuit operating in the above manner is that the transmitter Infrared only has a range of approximately ten microseconds (10 μsec) at least, up to ten milliseconds (10 ms) at most, in increments of ten microseconds (10 μsec), for each pulse and space. However, some infrared formats require space and impulse times greater than ten milliseconds. Because the minimum space and impulse time is only ten microseconds instead of zero (0), the spaces or impulses can not be concatenated to reach spaces or impulses, respectively, greater than ten milliseconds. It has been determined that a pulse greater than ten milliseconds can be provided by two pulses with a single space of ten microseconds between them without creating a problem for the receiving device. In a particular way, as an example, a drop of ten microseconds in an impulse of ten milliseconds is less than one cycle (assuming a carrier of 56 KHz, the period is 17 microseconds). However, it has been determined that providing only an impulse of ten microseconds between two spaces causes a discrimination problem for the remote control transmitting receiver. Accordingly, it is desirable to have a remote control that operates to provide pulsed transmissions and / or remote controlled spaces, which exceed the maximum pulse duration and / or space.

Therefore, it is also desirable to have a method for transmitting a remote control signal when a pulse and / or space exceeds the maximum pulse duration and / or space.

COMPENDIUM OF THE INVENTION The present invention is a remote control and an associated method that provides a remote control transmission. In particular, the present invention is a remote control and an associated method, which provides an extended remote control transmission. More particularly, the present invention is a remote control and an associated method that extends an operating range of remote control transmissions of the impulse / space combination type. In one form, the present invention is a remote control comprising a first circuit, and a chronometer circuit. The first circuit operates to generate a transmission comprising first and second portions. The first portion is of a duration within a first range of ti-me. The second portion is of a duration within a second time range. The first circuit also operates to generate a signal indicating the end of the transmission of the first and second portions. The chronometer circuit is in communication with the first circuit, and operates to make the first circuit signal inactive when a duration of time of a second portion exceeds the second time range. The stopwatch circuit further operates to generate a replacement signal for the signal of the first circuit after the expiration of the time duration of the second portion. In another form, the present invention is a method for generating a remote control transmission. The method includes the steps of: (a) generating a remote control transmission comprising first and second portions, the first portion of a duration that is within a first time range, and the second portion of a duration that is within a second time range; (b) generating a signal indicating the end of the transmission of the first and second portions; (c) inactivating the signal indicating the end of the transmission when the time duration of a second portion exceeds the second time range; and (d) generating a replacement signal for the signal indicating the end of the transmission after the expiration of the time duration of the second portion. In yet another form, the present invention is a method for extending a remote control transmission beyond a range of space amplitude of a remote control, the remote control having an integrated circuit operating to generate a remote control transmission comprising an impulse and space, the momentum having an amplitude of pulse within a range of pulse amplitude, and space having an amplitude of space within a range of space amplitude, the integrated circuit also operating to generate a signal indicating the end of the transmission. The method includes the steps of: (a) providing an interrupt signal to the integrated circuit after transmitting the transmission to a remote control, by operating the interrupt signal to temporarily disable the generation of another transmission by remote control; (b) providing a time interval equal to the amount of time that this space will exceed the range of space amplitude, the time interval being equivalent to a space; and (c) enable the generation of another remote control transmission after the expiration of the time interval.

BRIEF DESCRIPTION OF THE DRAWINGS The aforementioned and other characteristics and advantages of this invention, and the way to obtain them, will become clearer, and the invention will be better understood, referring to the following description of the embodiments of the invention, taken in conjunction with the accompanying drawings, in which: Figure 1 is a representation of an exemplary system embodying the present invention. Figure 2 is a functional block diagram simplified of the system of Figure 1. r Figure 3 is a representation of another example system i incorporating the present invention. Figure 4 is a simplified functional block diagram of the system of Figure 3. Figure 5 is a graph "of an example remote control signal format Figure 6A-E are time diagrams for different remote control signals. In accordance with one aspect of the present invention, Figure 7 is a block diagram of one embodiment of the present invention, Figure 8 is a block diagram of a particular embodiment of the present invention. flow illustrating a simplified view of the mode of operation of the present invention, Figure 10 is a flow chart illustrating a more particular example form of operation of an embodiment of the present invention. corresponding through the different views The exemplifications stipulated herein illustrate the preferred embodiments of the invention, and these axes mplifications should not be construed to limit the scope of the invention in no way.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, and more particularly to Figure 1, there is shown an example electronic system, generally designated in ten, wherein the present invention can be incorporated. The electronic system 12 is representative of any type of electronic device, and more particularly, of any type of consumer electronic device. The consumer electronic device can be a television, a television signal receiving device, VCR, DVD, or the like. The remote control 14 is representative of a typical manual remote control that operates to produce and send a transmission or control signal representing an action for the electronic device 12, to be performed in response to the actuation of a button or a key 16 of the remote control 1. The transmission of a remote control signal is preferably done wirelessly, and can take any form, such as by radio frequency signals, infrared (IR) radiation, or the like. The remote control signal can take any form, but preferably it is a coded signal of a previously defined or previously determined format. The device electronic 12 operates to receive and decode the remote control signal. Once decoded, the electronic device 12 operates to carry out a particular command for the remote control signal. The remote control 14 includes a plurality of buttons or keys 16, which allow a user to control at least some of the functions / features of the electronic device 12. The actuation or pressing of a button 16 causes the remote control 14 to produce and send a transmission corresponding to the button pressed. The button is associated with, and initiates, a function / feature of the electronic device 12. Each button is associated with a unique signal that is received and interpreted by the electronic device 12. When the electronic device 12 receives the single signal, the unique signal correlates with the characteristic / function and / or appropriate operation. In Figure 2, a simplified functional block diagram of electronic system ten is shown. The electronic device 12 includes a processing unit, a circuit and / or a logic 18, a remote control signal receiver 20, and other different circuits / logic / components 22. The processing unit 18 provides the main processing for the device 12. The receiver 20 provides for the reception of the remote control signals from the remote control 1. The decoding of a remote control signal can be performed by the receiver 20 and / or by the processing unit 18. The other circuits / logic / components 22 are representative of the different circuits, logic, and / or other components of the particular electronic device 12. The remote control 14 includes a button / key / logic circuit 24, which operates to receive a button / key signal from a button / key 16 of the remote control 14. The button / key / logic circuit 24 interprets which button / key 16 of remote control 14 was selected by the user. The remote control 14 further includes a transmission generator 26 that operates to receive a button / key signal from the circuit / button / key logic 24, and to generate or produce an appropriate remote control signal is (ie, a signal from encoded remote control for the particular button / key selected). A transmitter 28 receives the coded remote control signal from the transmission generator 26, and transmits the encoded remote control signal to the electronic device 12. Referring now to Figure 3, another example system, generally designated at 40, is illustrated, wherein the present invention can be incorporated. The electronic system 40 includes a television signal receiver 42 as an electronic device (normally and subsequently hereinafter, television), a remote control 44 for the television 42, an auxiliary electronic device 48, and an auxiliary remote control 50. The auxiliary electronic device 48 may be an upper box (ie, cable box, satellite receiver, or the like), a DVD, a VCR, or any another electronic device that uses and / or processes television signals. Accordingly, the auxiliary electronic device 48 is in communication with the television 42. In addition, the electronic system 40 includes an auxiliary remote control 50 which is in communication with the television 42. The remote control 44 includes a plurality of buttons / keys 46. , and operates in a manner similar to the remote control 14 of the electronic system ten of Figure 1. The remote control 44 operates to provide control signals to the television 42 in a previously defined or previously determined format. The television 42 operates to receive and interpret the remote control signals, in order to perform the commands requested, as provided by the remote control signals. The auxiliary electronic device 48 also operates to receive and interpret remote control signals. Although not shown, the auxiliary electronic device 48 normally has an associated remote control device. Auxiliary electronic devices 48, however, use remote control signals of a previously format defined or previously determined, which is different from the previously defined / previously determined format of the remote control 44. Instead of using two remote controls, the auxiliary remote control 50 operates to convert and transmit any remote control signal from the remote control 44 to be used by the auxiliary electronic device 48. More particularly, the television 42 provides the remote control signal received from the remote control 44 to the auxiliary remote control 50 when it is necessary and / or appropriate for the auxiliary electronic device 48 to receive / use the particular remote control signal that was generated by the remote control 44. Then the auxiliary remote control 50 provides an auxiliary remote control signal (preferably in a wireless manner) to the auxiliary electronic device 48. The auxiliary remote control 50 may need convert or reformat the remote control signal received from the TV 4 2 for the particular format scheme of the auxiliary electronic device. In Figure 4, a simplified functional block diagram of the electronic system 40 is shown. The remote control 44 includes a button / key / logic circuit 60, a transmission generator 62, and a transmitter 64. The key button / circuit / logic 60 operates to receive a button / button signal from a button / key 46 selected / pressed. The transmission generator 62 operates to generate / produce a coded remote control signal for the particular button / key selected. The transmitter 64 operates to transmit (preferably wirelessly, such as by infrared) the encoded remote control signal. The television 42 includes a visual display 52, a processing unit 54, a remote control signal receiver 56, and another circuit / logic / components 58. The remote control receiver 56 operates to receive a remote control signal from the control remote 44. The processing unit 54, together with the other circuits / logic / components, processes the remote control signal in an appropriate manner. The auxiliary remote control 50 includes the processing / logic circuit 66, a transmission generator 68, and a transmitter 70. The processing / logic circuit 66 operates to receive the remote control signal from the television 42 that received the control signal remote control from the remote control 44. The transmission generator 68 operates to provide an auxiliary remote control signal that is encoded for the auxiliary electronic device format 48. The transmitter 70 operates to transmit the auxiliary remote control signal to the auxiliary electronic device 48. .

The auxiliary electronic device 48 includes a processing unit 74, a remote control receiver 72, and other circuits / logic / components 76. The remote control receiver 72 operates to receive an auxiliary remote control signal from the auxiliary remote control that is format for the auxiliary electronic device 48. Referring to Figure 5, a graphic representation of an exemplary remote control signal, generally designated as RCS (Remote Control Signal), produced and / or generated by any of the devices is shown. to remote control 14, 44, and / or 50. The remote control signal consists of a first portion P, and a second portion S. The first portion P is a pulse portion of the remote control signal, while the second portion S is a space portion of the remote control signal. The first portion P is limited within a first range of pulse time, duration, or pulse amplitude, designated between ti and t, while the second portion S is limited within a second time range of space, duration, or amplitude of space, designated between t2 and t3. Each time range has a duration that is not zero or a minimum duration, and a maximum duration. Normally, the pulse time range is between approximately ten microseconds (10 μsec) and ten milliseconds (10 msec), while the time range of space is between approximately ten microseconds (10 μsec) and ten milliseconds (10 msec). Each button / key of the remote control thus has a unique combination of impulse-space (a pulse of a previously determined time range plus a space of a predetermined time range) that is generated and transmitted. Referring to Figure 8, a simplified block diagram of an auxiliary remote control, generally designated at 80, and known as an IR Blaster (Infrared Burst) is illustrated. The IR Blaster is manufactured by Thomson Consumer Electronics of Indianapolis, Indiana. The IR Blaster 80 is typical of "Infrared Blast" devices, where an input signal (here, a remote control signal) is amplified and / or retransmitted in an infrared format to control another electronic device (see Figures 3 and 4). In this mode, the IR Blaster 80 is used to receive, amplify, and retransmit infrared remote input signals. The retransmitted infrared remote control signals are in a remote / infrared control format, which is compatible with an auxiliary electronic device. The IR Blaster 80 has an infrared receiver circuit / logic 82, an application-specific integrated circuit (ASIC) 86, and another circuit / logic 84. The specific integrated circuit of the Application 86 operates to generate / produce and output / transmit infrared remote control signals. The specific integrated circuit of the application 86 includes, among others, circuit / logic 98, a clock cell 88, an infrared transmitter block / cell 90, an output comparison block / cell 92, a transmitter control register infrared 94, and an output comparison control register 96. For infrared transmissions that do not need to be modified, the application-specific integrated circuit provides a combination of pulse and space to the infrared transmitter control register 94 before the signal The infrared remote control (the pulse and space combination signal) is transmitted by the infrared transmitter cell 90 (ie, a "normal" infrared transmission). Due to different design considerations, the application-specific integrated circuit 86 is normally limited to provide a combination of momentum and space within the pulse and space durations described above. When one pulse is to exceed the maximum pulse amplitude, the application-specific integrated circuit provides a space of the minimum amplitude of space after the pulse of the maximum pulse amplitude before another pulse of the remaining pulse time amplitude . The device Receiving electronic normally is not affected by the minimum amplitude space within the extended pulse. However, when a space is to exceed the maximum amplitude of space, such as that shown in Figure 6A, the addition of a pulse of a minimum pulse amplitude will generally not be affected by the receiving electronic device. As shown in Figure 6B, the normal infrared output (IR_OUTA_NOMODIFIED) from the application-specific integrated circuit, produces an unwanted "burst" pulse at the end of the maximum amplitude of space. In accordance with one aspect of the present invention, when it is necessary for the application-specific integrated circuit to produce and transmit an infrared remote control signal having a space that is greater than the maximum amplitude of space, the specific integrated circuit is disabled. of the application in order to generate an extended space. In particular, the infrared transmitter cell of the specific integrated circuit of the application 90 is disabled, while an extended space is generated / produced. The generation / production of the extended space remote control infrared signal is provided by a "hardware" mode / implementation, and / or by a "software" mode / implementation. In accordance with the software modality of the present invention, when the specific integrated circuit of the application 86 will produce a space of a longer duration than the minimum amplitude of space, the output comparison stopwatch cell 92 is used as an internal software stopwatch, while not being uses the associated output type of the specific integrated circuit of the application. The infrared transmitter cell 90 is used to generate the pulse, while the output comparison stopwatch cell 96 generates / provides the space. More particularly, when a current pulse-space sequence expires, the infrared transmitter cell 90 becomes inactive by not reloading the pulse and space recorder 94 for the next sequence. While the infrared transmitter cell 90 is inactive, a low (logic) (0 volts) occurs on the associated peak IR_OUT of the application-specific integrated circuit 86. Then the output comparison cell 92 is set to expire (it is say, generate an interruption 'at the end of the desired space extension duration (see Figure 6E) .After the desired extended space duration expires, an interruption of the output comparison timer is generated. output comparison activates the infrared transmitter cell 90, where then a pulse and space sequence is loaded into the control register of the infrared transmitter 94 for the transmission of the next pulse-space combination. In accordance with a hardware embodiment / implementation of the present invention, and referring further to Figure 7, when the specific integrated circuit of the application 86 will produce a space of greater duration than the minimum amplitude of space, the cell of the Infrared transmitter 90 preferably becomes inactive in the same manner as the "software" implementation. However, an output comparison timer is output / output peak to drive the desired space (or unmodulated pulse) over the associated output peak. When driven, output from the output comparison stopwatch cell 92, by means of the output comparison control register 96, will override the output of the infrared transmitter based on the selected resistance value for the associated signals, as described later. In this way, the output comparison is established as an "open drain", which would have no effect on the high (logical) state, but would ground the IR-OUT signal in a low (logic) condition. The output comparison timer 92 can be triggered or started either on the rise edge or the fall of the infrared pulse. In case the fall edge is used, the output comparison stopwatch cell 92 is used to keep IR_OUT low until a timeout is reached, at which point an interruption is generated. Then the interrupt disables the output comparison timer 92, and enables the IR__OUT for the next pulse. This is illustrated graphically by the time diagrams of Figures 6C, 6D, and 6E. Figure 7 illustrates, in block diagram form, the use of the output comparison block / cell 92, to provide a space to the buffer zone 100, in order to provide a modified IR_OUT signal. The output comparison register 96 provides an output comparison enable signal to the output comparison block 92, in order to cause the output comparison block 92 to provide the amplitude of extended space. The different blocks of the output comparison cell 92 provide the time and the output of the extended space amplitude to the buffer zone 100. The signal from the output comparison cell 92 cancels any output from the infrared transmitter block 90 by resistor R2. The value of the resistor R2 is selected to be in the ratio of 10: 1, in order to ensure that the IR-OUT signal can be overridden by the output comparison. Referring to Figure 9, a flow chart, generally designated at 120, is shown of a Example general operation form of the present invention. Initially, in step 122, the remote control determines the amplitude of space of the remote control signal (RCS) to be sent. Once the space length of the remote control signal is determined, it is determined whether the length of the space exceeds the maximum amplitude of space, in step 124. If the remote control signal does not exceed the maximum amplitude of space , then the remote control continues with the normal transmission of the remote control signal by the infrared transmitter, in step 126. However, if it is determined that the remote control signal needs to exceed the maximum amplitude of space, it is disabled. generation of the remote control signal by the infrared transmitter for a predetermined time that substantially corresponds to the time duration of the extended portion of the space, in step 128. This process occurs whether the present invention is implemented in the hardware or the software. Referring to Figure 10, there is shown a flow chart, generally designated at 130, illustrating an exemplary form of operation of the present invention with respect to the embodiment implemented in the hardware of the present invention. In step 132, the structure of the space (i.e. the length of the space) is determined. If the structure of space is not greater than the maximum amplitude of space, in step 134, then the infrared transmitter uses the normal transmission scheme, in step 136. Otherwise, if in step 134 it is determined that the structure of the space is greater than the maximum amplitude of space, the The infrared transmission peak of the application-specific integrated circuit is established in a port for general purposes in step 138. In step 140, the peak is set for general purposes to make a space. The output comparison cell output comparison timer is set to time the desired extended space duration, in step 142. Any other software is allowed to run until the output comparison timer generates an interruption in the output comparison cell. step 144. Subsequently, the infrared transmission peak is set to use the infrared transmission cell in step 146. Also, the infrared transmitter is set to establish the next pulse-space sequence. Although this invention has been described as having a preferred design, the present invention may be further modified within the spirit and scope of this disclosure. Accordingly, it is intended that this application cover any variations, uses, adaptations of the invention, using its general principles. In addition, this application is intended to cover the departures from this disclosure that come into the practice known or accustomed in the art to which this invention pertains, and which falls within the limits of the appended claims.

Claims (12)

1. A remote control comprising: a first circuit operating to generate a transmission comprising first and second portions, the first portion of a duration within a first time range, and the second portion of a duration within a second time range , and to generate a signal indicating the end of the transmission of the first and second portions; and a chronometer circuit in communication with the first circuit, and operating to make the first signal of the circuit indicating the end of the transmission inactive, when a time duration of the first and second portions exceeds a previously determined time , and to generate a replacement signal for the first signal of the circuit indicating the end of the transmission after the expiration of the time duration of the second portion. The remote control of claim 1, wherein the first portion comprises a pulse, and the second portion comprises a space. 3. The remote control of claim 1, wherein the first circuit and the chronometer circuit are incorporated er. an integrated circuit. 4. The remote control of claim 3, in where the integrated circuit is a specific integrated circuit of the application. 5. The remote control of claim 1, wherein the first circuit operates to generate a transmission using infrared radiation. 6. The remote control of claim 1, wherein the first time range is from ten microseconds to ten milliseconds, and the second time range is from ten microseconds to ten milliseconds. The remote control of claim 1, wherein the signal indicating the end of the transmission of the first and second portions comprises an interruption. The remote control of claim 1, wherein the first circuit comprises a transmitter cell, and the chronometer circuit comprises an output comparison stopwatch cell. 9. A method for generating a remote control transmission, which comprises the steps of: generating a remote control transmission comprising first and second portions, the first portion of a duration that is within a first time range, and the second portion of a duration that is within a second time range; generating a signal indicating the end of the transmission of the first and second portions; inactivating the signal indicating the end of the transmission when a time duration of a second portion exceeds a predetermined time; and generating a replacement signal for the signal indicating the end of the transmission after the expiration of the time duration of the second portion. The method of claim 9, wherein the step of generating a remote control transmission comprising first and second portions includes generating a remote control transmission comprising first and second portions, the first portion comprising a pulse, and comprising the second portion a space. The method of claim 9, wherein the step of inactivating the signal indicating the end of the transmission of the first and second portions includes: inactivating the signal indicating the end of the transmission of the first and second portions by means of of the software The method of claim 9, wherein the step of inactivating the signal indicating the end of the transmission of the first and second portions includes: inactivating the signal indicating the end of the transmission of the first and second portions by means of of the hardware 14. The method of claim 9, wherein the The first time range is ten microseconds to ten milliseconds, and the second time range is ten microseconds to ten milliseconds. The method of claim 9, wherein the step of generating a remote control transmission includes generating a remote control transmission of infrared radiation. 16. The method of claim 9, wherein the steps of generating a transmission to remote control and generating a signal indicating the end of the transmission are carried out by means of a cell of the transmitter, and the steps of inactivating the signal and generating a replacement signal are carried out by means of a cell of exit comparison stopwatch. 17. In a remote control having an integrated circuit that operates to generate a remote control transmission comprising a pulse and space, the pulse having an impulse amplitude within a range of pulse amplitude, and the space having an amplitude of space within a range of space amplitude, the integrated circuit also operating to generate a signal indicating the end of the transmission, a method for extending the transmission beyond the range of space amplitude, which comprises the steps of: providing an interrupt signal to the integrated circuit after transmitting the transmission to remote control, operating the interruption signal to temporarily disable the generation of another transmission to remote control; provide a time interval equal to an amount of time that that space will exceed the range of space amplitude, the time interval being equivalent to a space; and enable the generation of another transmission to remote control after the expiration of the time interval. The method of claim 17, wherein the step of providing an interrupt signal comprises providing an interrupt signal by means of the software. The method of claim 17, wherein the step of providing an interrupt signal comprises providing an interrupt signal via the hardware. The method of claim 17, wherein the step of providing a time interval comprises providing a time slot by means of an output comparison stopwatch cell.