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Contents
1. in the step 511 the logic value of zero is assigned to all source codes R i so as to indicate that control instructions have not been received yet Subsequently a message is received in a manner already described in the sub program 52 the master address MA of the source of this message is determined in the step 53 and the control instruction CM is read in the step 54 If the control instruction is actually executed in the sub program 58 a step 591 is subsequently performed In this step the current instruction CM is stored in the instruction code OLDCM and the counter is set to zero More particularly all source codes R i acquire the logic value 0 again after a control instruction has been executed except for the source code R MA which corresponds to the apparatus from which the executed control instruction was received When a control instruction is received within a predeter mined period of time determined in step 55 after the previous execution of the same instruction determined in step 56 step 571 is now performed In this step 571 it is checked whether the source code R MA has the logic value 1 If R MA has the logic value 0 the control instruction from the corresponding apparatus has not been received since the last execution Such an instruction is not executed because the instruction originating from another apparatus has just been performed namely from the apparatus for which currently the source c2. which instruction is the first to be 20 25 35 45 50 55 60 65 6 received by the audio amplifier The Figure shows that the monitor wins the arbitration except in the case of control instruction 38 which is preceded by control instruction 48 from the video recorder As is shown in a shaded form in the Figure the control instructions 36 39 from the monitor are invariably performed This also applies to the control instruction 38 The corresponding control instruction 48 from the video recorder is ignored because the predeter mined period of time T has not elapsed yet upon its reception FIG 6 shows the flow chart of another example of the control program In this Figure identical reference numerals denote the same elements as in FIG 3 Characteristic of the example of the control program shown in FIG 6 is the presence of an array R in the RAM of the microprocessor The array R stores a source code for each apparatus with the master address i in the form of an array element R i which can assume the logic value 0 or 1 In the course of the control program the logic value R i 0 means that control instructions have not yet been received from the correspond ing apparatus with master address i An initial step 511 in which as previously described a pseudo value is assigned to the instruction code OLDCM and the value of zero is assigned to the counter t is performed by the control program Moreover
3. 370 85 1 5 128 789 7 1992 Abramovitz 359 118 5 132 679 7 1992 Kubo et al 340 825 22 5 367 316 11 1994 Ikezaki 345 158 FOREIGN PATENT DOCUMENTS 0071296 2 1983 European Pat Off 0137225 4 1985 European Pat Off 0165600 12 1985 European Pat Off 0423739 4 1991 European Pat Off H04B 1 20 582343 2 1994 European Pat Off H09B 1 20 2900380 7 1979 Germany OTHER PUBLICATIONS The D2B Concept Of The User Manual Of Single Chip 8 Bit Microcontrollers Published By Philips Electronics Components And Materials 1986 pp 551 609 Primary Examiner William M Treat Assistant Examiner Saleh Najjar Attorney Agent or Firm Laurie E Gathman 57 ABSTRACT In a communication system comprising different appara tuses which are coupled together by a bus a control instruc tion for example a remote control command may be passed on by a plurality of apparatuses to the apparatus performing the instruction In order that the apparatus performs such an instruction only once the control circuit in the apparatus memorizes from which source the performed instruction has been received The identical control instructions received from the other apparatuses are ignored for a predetermined period of time 8 Claims 4 Drawing Sheets INTERFACE CIRCUIT 2 MONTOR INTERFACE CIRCUIT 42 MICROPROCESSOR VIDEO RECORDER A
4. UDIO MICROPROCESSOR AMPLIFIER ad ax ooo ooo 200 U S Patent Nov 26 1996 Sheet 1 of 4 5 579 496 ie INTERFACE IRCUIT 7 MONTOR MICROPROCESSOR VIDEO RECORDER INFRARED Z N OOO ooo D AUDIO MICROPROCESSOR AMPLIFIER FIG 1 1 151 161 161 161 SEO T3 ai 0 15 16 16 n mv 1 16 16 FIG 2 U S Patent Nov 26 1996 Sheet 2 of 4 5 579 496 OLDCM 0 OLDMA 0 tos OLDCM CM LDMA MA t 0 FIG 3 U S Patent Nov 26 1996 Sheet 3 of 4 5 579 496 1 t 0 FIG 4 36 46 y 9 48 3 33 T t 0 t t 0 t 0 FIG 5 36 5 y 48 38 33 8 U S Patent Nov 26 1996 Sheet 4 of 4 5 579 496 OLDCM O 511 t 0 for i to N do R i 0 572 OLDCM CM 0 for i to N do R 1 0 R MA FIG 6 5 579 496 1 METHOD AND APPARATUS FOR PROCESSING CONTROL INSTRUCTIONS RECEIVED FROM MULTIPLE SOURCES CONNECTED TO A COMMUNICATION BUS This is a continuation of application Ser No 08 209 681 filed Mar 10 1994 which is a continuation of application Ser No 07 853 366 filed on Mar 18 1992 both now abandoned BACKGROUND OF THE INVENTION The invention relates to a method of processing control instructions received from at least two identifiable sources via a communication connection Such a method can be used inter alia in apparatuses which are coupled together by use of a bus These may be audio and vi
5. United States Patent no Van Steenbrugge AAA 54 METHOD AND APPARATUS FOR PROCESSING CONTROL INSTRUCTIONS RECEIVED FROM MULTIPLE SOURCES CONNECTED TO A COMMUNICATION BUS 75 Inventor Bernard Van Steenbrugge Redhill United Kingdom 73 Assignee U S Phillips Corporation New York N Y 21 Appl No 483 629 22 Filed Jun 7 1995 Related U S Application Data 63 Continuation of Ser No 209 681 Mar 10 1994 aban doned which is a continuation of Ser No 853 366 Mar 18 1992 abandoned 301 Foreign Application Priority Data 2 1991 EP European Pat Off 91200758 51 Int CL G09G 3 02 GOSB 19 00 52 U S CL a s 395 567 340 825 22 345 158 345 169 348 734 58 Field of Search 364 138 358 194 345 158 395 375 56 References Cited U S PATENT DOCUMENTS 3 1976 Fehlmer et al 342 389 4 040 031 8 1977 Cassomet 395 250 4 209 838 6 1980 Alcorn Jr et al 4 236 203 11 1980 Curley et al 4 482 947 11 1984 Zato et al 364 138 3 947 849 Patent Number 5 579 496 45 Date of Patent Nov 26 1996 4 751 581 6 1988 Ishiguro etal 368 194 1 4 897 718 1 1990 Testr et al 358 194 1 4 897 834 1 1990 Peterson et al 370 85 1 4 969 146 11 1990 Twitty et al
6. al apparatuses Such an internal source is not identified by the master address of the apparatus but by a sub device address which is incorporated in the data fields of a D2B message I claim 1 A method for processing a plurality of control instruc tions received from at least two sources which are coupled to a communication connection the control instruction being intended for controlling an apparatus and said method comprising the steps of a receiving and executing a first control instruction from a first source b storing a first instruction code representing said first control instruction and a first source code identifying said first source c receiving a second control instruction from a second source d comparing a second instruction code representing said second control instruction to said first instruction code and comparing a second source code identifying said second source to said first source code and e disregarding said second control instruction if said second source is different than said first source and said second instruction code matches said first instruction code and executing said second control instruction if said second instruction code is different than said first instruction code or said second source is the same as the first source 8 2 The method of claim 1 wherein said second control instruction is executed if the elapsed time between reception of said first control instruction and reception
7. an identical control instruction which has been received within the predetermined period of time T after the instruc tion 34 has been carried out The volume is therefore raised by one step which is in conformity with the volume up command generated once If the same command is generated again some time later the audio amplifier will again receive two control instructions In the Figure the new control instruction from the monitor is denoted by 35 and the new control instruction from the video recorder is denoted by 45 As indicated in FIG 4 the video recorder won the arbitra tion procedure so the audio amplifier will receive the control instruction 45 first Now the audio amplifier will perform the control instruction 45 from the video recorder which instruction is shaded in the Figure The control instruction 35 from the monitor is now ignored The sound volume is again raised by not more than one step FIG 5 diagrammatically shows in a time sequence the messages which occur on the communication bus if the volume up key on the remote control unit 5 see FIG 1 is kept depressed In this situation the volume up com mand is generated in a repetitive manner with intervals of approximately 100 150 ms In FIG 5 the corresponding control instructions from the monitor are denoted by 36 39 and the control instructions from the video recorder are denoted by 46 49 It always depends on the result of the arbitration procedure
8. and a source code corresponding to the source thereof are stored upon reception of a control instruction an instruction code corresponding to the received control instruction is compared with the stored instruction code and ifthey match the source code corresponding to the source of the received control instruction is determined and checked whether the source code matches the stored source code The execution of the received control instruction is omitted if the source code does not match the stored source code It is thereby achieved that from a series of identical control instructions from different sources only the instruction is carried out from the source whose source code was already stored The control instructions from the other sources are redundant and are ignored If repetitive control instructions are received only the instructions from the one and the same source is carded out A further embodiment of the method is characterized in that execution of the received control instruction is omitted if also less than a predetermined period of time has elapsed since the reception of the control instruction executed before In that case the control instruction from the trans mitter whose control instruction is received first after the predetermined period of time has elapsed will be performed Another embodiment of the method is characterized in that the source code corresponding to the source of the received control instruction is also sto
9. de OLDMA If the two addresses are equal the control instruction is executed However if the contro instruction originates from another apparatus the instruction will not be carried out The control program described hereinbefore will now be used in the communication system shown in FIG 1 To this end it is assumed that apparatus 2 in FIG 1 is an audio amplifier apparatus 3 is a television monitor and apparatus 4 is a video recorder The monitor 3 and the video recorder 4 receive an infrared command volume up from the remote control unit 5 They cannot carry out this command themselves and have been programmed in a previously performed installation phase to pass on sound control com mands to the audio amplifier 2 via the communication bus 1 FIG 4 diagrammatically shows in a time sequence the messages which occur at the communication bus in response to the volume up command More particularly FIG 4 shows a control instruction 34 from monitor 3 to amplifier 2 and a control instruction 44 from video recorder 4 to amplifier 2 As has been shown in the Figure the control instruction 34 is the first to be transmitted because monitor 3 has won the arbitration procedure Both control instruc tions indicate that the sound volume must be raised by one step The audio amplifier will now execute control instruc tion 34 which is shown in a shaded form in the Figure The control instruction 44 is not carried out because it relates to
10. deo apparatuses but aim for example washing machines microwave ovens luminaires and the like The invention also relates to an apparatus provided with a control circuit adapted to perform the method Lately apparatuses have been provided with a connection for coupling them to a common bus By use of this bus a plurality of apparatuses can be operated from one point in the house It is also possible to transmit all kinds of control instructions from each apparatus to any other apparatus which is connected An example of such a bus is known under the name of Domestic Digital Bus frequently abbre viated to D2B bus which is described for example in chapter 11 The D2B Concept of the User Manual of Single Chip 8 bit Microcontrollers published by Philips Electronic Components and Materials 1986 The D2B bus provides easy operation of for example an audio video system including a plurality of apparatuses For example a video recorder may automatically switch on a television receiver and tune this receiver to the correct video recorder channel when a video tape is to be displayed Apparatuses having a D2B connection will often also have their own infrared receiver so that they can also be used as stand alone apparatuses Such apparatuses may be imple mented in such a way that a control instruction which has been received by the infrared receiver and cannot be carried out by the apparatus itself is passed on via the D2B bus to an apparat
11. es of some messages occur ring on the communication bus FIG 6 shows the flow chart of a further example of the control program performed by the control circuit shown in FIG 1 FIG 7 shows a further example of some messages which occur on the communication bus DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION FIG 1 shows diagrammatically a communication system The system includes a communication bus 1 for transmitting control instructions In this case three apparatuses 2 3 and 4 are connected to this communication bus The apparatuses may be simple or complicated for example a television apparatus a recorder a washing machine a microwave oven a luminaire a sensor for the outside temperature etc The function of the apparatus is controlled by a local microprocessor 21 31 and 41 The microprocessor com prises in further known manner a ROM for storing a control program and a RAM for storing variable dam For receiving control instructions from other apparatuses and for trans mitting control instructions to other apparatuses the micro processor in each apparatus is coupled to the communication bus 1 by an interface circuit 22 32 and 42 Such an interface circuit is for example the integrated circuit SAx1235 of the firm of Philips In the apparatuses 3 and 4 the microproces sor is also coupled to an infrared receiver 33 and 43 for receiving operating commands which are generated by a remote control uni
12. f the counter t is compared with a predetermined value T If the value of t exceeds T a predetermined period of time for example 1 second has elapsed and a sub program 58 is performed The sub program 58 comprises the actual performance of the control instruction and is separately specified for each apparatus Subsequently the step 59 is performed In this step a value which is representative of the performed contro instruction is assigned to the instruction code OLDCM Moreover the master address MA which identifies the transmitter of the 5 579 496 5 control instruction is stored in the source code OLDMA Finally the value of zero is assigned to the counter t Thereafter the control program returns to the sub program 52 to check whether more control instructions are received If it has been determined in the step 55 that the prede termined period of time T has not elapsed yet when a control instruction is received it is checked in a step 56 whether the received control instruction CM is equal to the previously executed control instruction OLDCM If this is not the case the control instruction in the subprogram 58 is executed If the two control instructions are equal it is checked in a step 57 whether both of them have been transmitted by the same apparatus To this end the master address MA in the received message is compared in the step 57 with the master address of the previously performed instruction stored in the source co
13. instruction code matches said first instruction code and means for executing said second control instruction if said second instruction code is different than said first instruction code 6 The apparatus of claim 5 further including means for measuring the elapsed time between reception of said first contro instruction and reception of said second control instruction and wherein said second control instruction is executed if the elapsed time between reception of said first control instruction and reception of said second control instruction is at least equal to a predetermined period of time 7 The apparatus of claim 5 further comprising f means for storing said second source code if said second control instruction is not executed and g means for erasing said first source code if said second control instruction is executed 8 The apparatus as claimed in claim 6 further compris ing f means for storing said second source code if said second control instruction is not executed and g means for erasing said first source code if said second control instruction is executed 25 30 35 40 45 50 55 60
14. ode R i 1 In a step 572 the value 1 is assigned to the source code R MA so as to establish that the control instruction has been received from this apparatus If it has been determined in the step 571 that R MA has the value 1 this may have two causes On the one hand the control instruction may originate from the apparatus whose previous instruction was performed On the other hand the control instruction may originate from an appara tus whose previous instruction was received but ignored In both cases the control instruction is executed now FIG 7 again shows diagrammatically in a time sequence the repetitive messages occurring on the communication bus ifthe volume up key on the remote control unit 5 see FIG 1 is kept depressed To explain this Figure the values of the source codes R 3 and R 4 are plotted on the time axis R 3 corresponds to monitor 3 and R 4 corresponds to video 5 579 496 7 recorder 4 In contrast to FIG 5 it is apparent from FIG 7 that control instruction 48 from the video recorder is now executed and that the control instruction 38 from the monitor is ignored This is accomplished by step 571 of the control program see FIG 6 In this step the source code R 4 is detected to have the value 1 when the control instruction 48 is received which is caused by the fact that a control instruction 47 has already been received before but not executed at that time from the video reco
15. of said second contro instruction is at least equal to a predetermined period 5 of time 3 The method of claim 1 further comprising the steps of f storing said second source code if said second control instruction is not executed and g erasing said first source code if said second control instruction is executed 4 The method of claim 2 further comprising the steps of f storing said second source code if said second control instruction is not executed and g erasing said first source code if said second control instruction is executed 5 An apparatus for processing a plurality of control instructions for controlling the apparatus received from at least two sources which are coupled to a communication connection said apparatus comprising a means for receiving and executing a first control instruction from a first source b means for storing a first instruction code representing said first control instruction and a first source code identifying said first source c means for receiving a second control instruction from a second source d means for comparing a second instruction code repre senting said second control instruction to said first instruction code and comparing a second source code corresponding to said second source to said first source code and e means for disregarding execution of said second con trol instruction if said second source code differs from said first source code and said second
16. ratus is switched on an initial value is assigned to a number of variables in the RAM of the microprocessor An instruc tion code OLDCM is intended to keep a record of the last control instruction performed by the apparatus A source code OLDMA is intended to keep a record of the apparatus from which the last performed contro instruction was received In the initial step 51 the two variables acquire a pseudo value for example the value of zero so as to indicate that no control instructions have been received yet A counter t has the initial value of zero This counter represents an elapsed time which is autonomically increased by the microprocessor In a sub program RCV which is denoted by the reference numeral 52 it is subsequently checked whether the appara tus is addressed by one of the other apparatuses via the communication bus As previously noted the slave address 14 in FIG 2 is to this end compared with the own address of the apparatus and in the case of recognition the acknowl edge bit A is transmitted Subsequently in a step 53 the received master address 13 in FIG 2 is stored in a variable which will be denoted by MA Finally the data fields 16 in FIG 2 are read in a step 54 These data fields constitute the actual control instruction which must be carried out by the addressed apparatus The control instruction thus received is provisionally stored in a variable which will be denoted by CM In a step 55 the count o
17. rder The audio amplifier thus switches as it were temporarily from execu tion of control instructions from monitor 3 to execution of control instructions from video recorder 4 This is particu larly sensible if there were circumstances which would lead to the absence of the control instruction 38 The control instruction 48 from the video recorder is thus executed if the control instruction 38 from the monitor is absent for example because the corresponding volume up command from the remote control unit has not reached the monitor due to a temporary interruption of the infrared light ray It is to be noted that the use of the method according to the invention is not limited to communication systems with a common communication bus For example an apparatus may also receive the control instructions from other appa ratuses via individual connections In that case a transmit ting apparatus is not identified by a master address which is comprised in a received message but by the physical location of the connection through which the control instruc tions are applied It is also to be noted that not all sources have to be external apparatuses For example one of the sources may be accommodated in the apparatus itself and function as a sub apparatus within this apparatus An infra red receiver built in an apparatus constitutes a sub device within the D2B system whose control instructions are equivalent to control instructions from extern
18. red if the execution of the control instruction is omitted and in that the source codes corresponding to the other sources are erased when the control instruction is being executed The effect achieved thereby will be explained with reference to an example Let it be assumed that of a series of identical control instructions from different transmitters the instruction from transmitter A is executed and the instruction from transmitter B is ignored It is now possible that the instruction from transmitter A is absent in a subsequent series of control instructions for example because the infrared receiver of the corresponding apparatus was temporarily covered It is also possible that 5 579 496 3 the control instruction from transmitter A in the subsequent series is received later than the control instruction from transmitter B for example because transmitter A has lost the previously mentioned arbitration procedure Of the subse quent series the control instruction from transmitter B is now performed Thus each control instruction is performed actually and without any delay BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 shows diagrammatically a communication system in which the method according to the invention is used FIG 2 shows the structure of a message transmitted via the communication bus shown in FIG 1 FIG 3 shows a flow chart of a control program performed by a control circuit shown in FIG 1 FIGS 4 and 5 show exampl
19. t 5 FIG 2 shows the structure an information level of a message transmitted via the communication bus For a detailed description at bit level reference is made to the Reference stated in the opening paragraph The message shown in FIG 2 comprises a start bit 11 a mode field 12 a master address 13 a slave address 14 a control field 15 and one or more data fields 16 The mode field 12 indicates the bit rate with which the message is transmitted The master address 13 comprises 12 bits and identifies the apparatus at whose initiative the message is transmitted This apparatus is referred to as the master station The slave address 14 also comprises 12 bits and indicates the addressed apparatus This apparatus is referred to a slave station The control field 15 describes the nature of the message and indicates inter alia whether the message comprises a read or a write operation It is to be noted that the master station and the slave station can both transmit and receive It will herein after be assumed that the master station operates as a 10 15 20 25 30 35 40 45 50 55 60 65 4 transmitter and the slave station operates as a receiver The data fields 16 comprise 8 bits each and indicate the control instruction to be transmitted Each data field is terminated by a bit not shown indicating whether the corresponding data field is the last of the message If a plurality of apparatuses is to use the comm
20. ult is that the volume is raised by two steps which may generally not have been the user s intention If the user keeps the volume up key on the infrared hand held remote control unit depressed this operating command is generated in a repetitive manner and both apparatuses will pass on the corresponding control instruction also in a repetitive manner to the audio amplifier The volume will now be raised twice faster than is desirable Apparatuses passing on a control instruction to another connected apparatus via the D2B bus will hereinafter be referred to as sources The apparatus for which these control instructions are intended is provided with a control circuit receiving and processing the control instructions It is to be noted that the control circuit can identify the source of a control instruction For this purpose and as indicated in the Reference each D2B message on the bus does not only include the control instruction and a slave address with which the apparatus is addressed but also a master address which identifies the source of the message SUMMARY OF THE INVENTION It is an object of the invention to provide a method preventing the unwanted consequences of identical control instructions which have been received more than once To this end the method according to the invention is characterized in that upon execution of a control instruction an instruction code corresponding to the executed control instruction
21. unication bus simultaneously or substantially simultaneously an arbi tration procedure will be carried out Briefly summarized the substance of this procedure is that during the transmis sion of the start bit the mode field and the master address a master station checks whether each transmitted bit is actu ally put on the bus If this is not the case the relevant master station will withdraw The arbitration procedure results in only one master station being active after the master address has been transmitted Other master stations will wait until the end of the message and at a later stage they will make another attempt to use the bus The remaining master station now transmits the slave address 14 of the apparatus for which a control instruction is intended As is shown in FIG 2 the slave address comprises a space 14 1 If a slave station recognizes its own address it will transmit an acknowledge bit A in this space If the master station does not detect this bit A it means that the slave station is not present or does not function The message is then immediately ended In a corresponding way the slave station transmits an acknowl edge bit in a space 151 after recognition of the control field 15 and in a space 161 after correct reception of each data field 16 FIG 3 shows a flow chart of a control program performed by the microprocessor in each apparatus In a step 51 of this control program which step is performed when the appa
22. us which does have the required facilities The latter apparatus then need not have an infrared receiver of its own or it may be accommodated in a closed space If more apparatuses having theft own infrared receivers are coupled together via the D2B bus a problem arises which will now be illustrated with reference to an example An audio video system comprises a video recorder a television monitor and an audio amplifier with loudspeakers The video recorder provided with an infrared receiver receives the operating command volume up from an infrared transmitter for increasing the sound volume by one step but it cannot carry out this command itself because it lacks a built in audio amplifier section The same applies to the television monitor which is also provided with an infrared receiver In a previously performed installation phase both apparatuses have been programmed to pass on control instructions relating to sound functions via the D2B bus to the audio amplifier accommodated in a cabinet The apparatuses will attempt to do this simultaneously or substantially simulta neously In response to an arbitration procedure described in the Reference the two instructions will be passed on to the audio amplifier one after the other The audio amplifier now receives the control instruction volume up from both 10 15 20 25 30 35 40 45 50 55 60 65 2 apparatuses and will carry out the two instructions The res
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