EP2136357A2 - Verfahren und System zum Ansteuern einer Signalisierungsvorrichtung - Google Patents

Verfahren und System zum Ansteuern einer Signalisierungsvorrichtung Download PDF

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Publication number
EP2136357A2
EP2136357A2 EP20090162753 EP09162753A EP2136357A2 EP 2136357 A2 EP2136357 A2 EP 2136357A2 EP 20090162753 EP20090162753 EP 20090162753 EP 09162753 A EP09162753 A EP 09162753A EP 2136357 A2 EP2136357 A2 EP 2136357A2
Authority
EP
European Patent Office
Prior art keywords
drive signal
microcontroller
signalling device
signal
serial
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP20090162753
Other languages
English (en)
French (fr)
Inventor
Lucio Bianchi
Stefano Ughi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Whirlpool EMEA SpA
Original Assignee
Indesit Co SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Indesit Co SpA filed Critical Indesit Co SpA
Publication of EP2136357A2 publication Critical patent/EP2136357A2/de
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/0207—Driving circuits
    • B06B1/0223—Driving circuits for generating signals continuous in time
    • B06B1/0238—Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave

Definitions

  • the present invention relates to a method for driving an acoustic signalling device according to the preamble of claim 1.
  • the invention also relates to a system capable of implementing such a driving method.
  • the invention is especially and preferably applicable to the field of household appliances, wherein an acoustic signalling device, e.g. a buzzer, is turned on at the end of a working cycle.
  • an acoustic signalling device e.g. a buzzer
  • a washing machine may activate an acoustic device in order to inform the user that the wash cycle has been completed; it is also known that freezers are available which carry out intensive cooling cycles (e.g. for cooling drinks quickly) and warn the user when said cycle has ended in order to prevent the drinks from freezing.
  • intensive cooling cycles e.g. for cooling drinks quickly
  • the acoustic signalling device employed is typically a buzzer driven by a microcontroller through a PWM output, e.g. a 4kHz timer with a 50% duty cycle.
  • microcontroller may however happen in some situations that the microcontroller has to drive a large number of devices, so that there are no PWM outputs available for driving additional acoustic devices or buzzers.
  • the present invention aims at providing an alternative method for driving a signalling device, in particular an acoustic signalling device, which requires an alternating input voltage, such as a buzzer.
  • the present invention is based on the idea of driving the signalling device through a serial output of the microcontroller, e.g. an SPI (Serial Peripheral Interface) output or a UART (Universal Asynchronous Receiver/Transmitter) output.
  • SPI Serial Peripheral Interface
  • UART Universal Asynchronous Receiver/Transmitter
  • the microcontroller can generate a periodic signal having a predetermined frequency and duty cycle.
  • the microcontroller By appropriately selecting the pattern and baud rate of the serial output, the microcontroller thus generates a periodic signal which can control the signalling device.
  • Buzzer 1 is an acoustic signalling device that emits a sound when it receives an alternating voltage having an appropriate frequency, in particular within the audible band.
  • the system of Fig. 1 and the driving method described below can be used with any other acoustic signalling device emitting an acoustic signal in response to an alternating voltage signal.
  • Buzzer 1 has a pair of terminals 10 and 11 respectively connected to the 12V direct voltage Vcc and to the collector of BJT transistor 2 in grounded emitter configuration.
  • Transistor 2 operates as a switch: when conductive, transistor 2 grounds terminal 11 of buzzer 1, so that across the buzzer terminals there is a voltage drop equal to Vcc; vice versa, when transistor 2 is not conductive terminal 11 receives Vcc, so that there is no voltage drop across the buzzer.
  • a resistor 3 arranged in parallel with buzzer 1 is used for locking terminal 11 to Vcc when the transistor is interdicted, i.e. when it is not conductive. Resistor 3 is also used for discharging any charge accumulated into the buzzer, which typically behaves like a capacitor.
  • microcontroller 4 For turning on the buzzer, microcontroller 4 is equipped with a serial interface through which it sends a drive signal over serial output 41 (e.g. a UART output), which then arrives at the base of transistor 2.
  • serial output 41 e.g. a UART output
  • the drive signal present at serial output 41 (shown by way of example in Fig. 2a ) consists of N bits set to the high logic value (e.g. 5V) and M bits set to the low logic value (e.g. 0V).
  • the drive signal depends on the transmission protocol and on the data sent through the serial interface.
  • the transmission protocol includes one start bit, 8 data bits and one stop bit; there is no parity bit.
  • Fig. 2a shows the signal generated by a UART peripheral for transmitting the data 0x55.
  • UART peripheral Normally, i.e. when not activated, UART peripheral outputs a high signal.
  • the subsequent eight bits contain the data 0x55, consisting of an alternate sequence of high and low bits.
  • the signal ends with a stop bit having a high logic value.
  • the signal thus generated has a duration T.
  • signal 2a a periodic signal with a period P equal to the duration of two bits and a 50% duty cycle.
  • UART peripheral will tend to hold output 41 in high state, as shown in Fig. 2a .
  • Microcontroller 4 is therefore programmed in a manner such that, as soon as the transmission of one data instance has ended, another data instance is then immediately transmitted, as shown in Fig. 2b .
  • the transmission of the new data instance is ensured by setting an interrupt when the buffer containing the data to be sent becomes empty, so as to reload the data automatically.
  • This solution ensures that the drive signal transmitted by the serial peripheral has a periodicity at least equal to duration T required for transmitting one data instance.
  • Fig. 2c shows a drive signal obtained by transmitting the data 0xFF.
  • a periodic drive signal is obtained only by programming the microprocessor in a manner such that the data instance 0xFF is continuously retransmitted.
  • the drive signal has a period P equal to time T required for transmitting one data instance according to the selected transmission protocol.
  • the baud rate (i.e. bit duration) being equal, the signal of Fig. 2c has a lower frequency than that of Fig. 2b , but its duty cycle is much greater.
  • the duration of the single bits and the data to be sent over the serial line it is thus possible to obtain a periodic signal having a predetermined frequency and duty cycle.
  • transistor 2 When the drive signal has a high logic value, transistor 2 becomes conductive and a 12V voltage is applied across buzzer 1.
  • transistor 2 When the drive signal has a low logic value, transistor 2 is interdicted and a 0V voltage is applied across buzzer 1.
  • the voltage applied across terminals 10 and 11 of buzzer 1 is therefore an alternating voltage with a predetermined frequency and duty cycle, which can cause the buzzer to buzz.
  • Fig. 3 shows a possible variant of the drive system of Fig. 1 , which may be used to advantage when no serial output is available for exclusively driving the buzzer.
  • This variant is based on the idea of using the serial line that drives the buzzer also as a line for communicating with the outside world, which is its natural function.
  • the drive circuit comprises a communication module 5 which allows the signal available at the microcontroller's serial output 41 to be transmitted alternately over two different lines: the first line (hereafter referred to as “drive line”) is intended for driving the buzzer, whereas the second line (hereafter referred to as “serial line”) is intended for serial communications.
  • the switching between the serial line and the drive line is controlled by the microcontroller through output 42.
  • Switching module 5 can be manufactured by using a single integrated circuit having two inputs 51 and 52 and two outputs 53 and 54.
  • the switch comprises two NAND ports and two inverters.
  • Input 51 that receives the signal from serial output 41 of microcontroller 4 is negated by means of a first inverter 55, and the signal thus negated is inputted to NAND port 56, whose output is connected to the serial line, and to NAND port 57, whose output is connected to the buzzer through transistor 2.
  • the switch control signal is sent from output 42 of the microcontroller and received by input 52 of the switch.
  • control signal is thus inputted to NAND port 56, negated by inverter 58, and then inputted, thus negated, to NAND port 57.
  • control signal If the control signal is high, then the signal outputted by serial output 42 will be carried over the serial line, while a constantly high signal will be present on the drive line.
  • serial output 41 By holding output 42 high, de facto the microcontroller allows serial output 41 to be used for serial communications with other devices connected to the serial line.
  • microcontroller 4 when microcontroller 4 holds the control signal low, then there will be a constantly high signal at serial output 41, and the signal present at microcontroller's serial output 41 will be found on the drive line.
  • the microcontroller By holding output 42 low, the microcontroller utilizes serial output 41 for generating a drive signal, as explained above with reference to Figs. 2a-2c , which signal drives switch 2 in order to turn on buzzer 1.
  • transistor 2 may be replaced with any other device or system capable of performing the described switch function, which is required for applying an alternating voltage to the acoustic signalling device.
  • Fig. 3 may comprise an additional inverter, arranged between output 54 of NAND port 57 and transistor 2.
  • the drive system described above with particular reference to an acoustic signalling device may also be used for driving any other signalling device, such as an optical signalling device, e.g. a LED.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Electronic Switches (AREA)
EP20090162753 2008-06-16 2009-06-16 Verfahren und System zum Ansteuern einer Signalisierungsvorrichtung Withdrawn EP2136357A2 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
ITTO20080470 ITTO20080470A1 (it) 2008-06-16 2008-06-16 Metodo e sistema per pilotare un dispositivo di segnalazione

Publications (1)

Publication Number Publication Date
EP2136357A2 true EP2136357A2 (de) 2009-12-23

Family

ID=40302159

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20090162753 Withdrawn EP2136357A2 (de) 2008-06-16 2009-06-16 Verfahren und System zum Ansteuern einer Signalisierungsvorrichtung

Country Status (2)

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EP (1) EP2136357A2 (de)
IT (1) ITTO20080470A1 (de)

Also Published As

Publication number Publication date
ITTO20080470A1 (it) 2009-12-17

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