ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Onboard control system with speech output of information. Encyclopedia of radio electronics and electrical engineering Encyclopedia of radio electronics and electrical engineering / Automobile. Electronic devices Modern cars are equipped with a large number of information and indicator devices and warning lights designed to monitor the performance of their main systems. However, the visual information obtained with their help, on the one hand, requires the driver's attention to be distracted from the control of the traffic situation, and on the other hand, it is not convenient enough and cannot always be noticed in time. This problem is especially relevant for motorists with little driving experience, and its consequences can be very serious. For example, readings of an engine temperature gauge about overheating that are not noticed in time can lead to its failure and, as a result, to high financial costs. Unnoticed failures of other components of the car, such as brake and lubrication systems, alternator, rear signal lights, etc., can turn out to be no less unpleasant. The "talking" on-board control system (BCS) offered to the attention of readers is intended for use in domestic and imported cars and provides information about detected malfunctions in speech form. Messages are given in a male or female voice (depending on the program used and the firmware of the "speech" ROM), and the voice quality corresponds to "telephone" according to the Windows SoundSystem classification. Several copies of this device have been used for more than a year on cars of various brands and have shown high reliability and efficiency. The device (Fig. 1) is implemented on the basis of a single-chip microcomputer KR1816BE35. Chip DD6 performs the functions of the address bus shaper, and DD7 - external program memory. Port P1 OMEVM DD10 is used to generate high addresses "speech" ROM DD11, which contains digitized and in a certain way compressed speech information. The low bits of the P2 port of the OMEVM are used to address the DD7 program ROM, and the high bits of this port, together with the DD13 and DD8.4 ICs, are used to select external devices: the DD11 speech ROM, the input data switch DD3-DD5 and the audio path register DD12. On the logic elements DD8.1, DD8.2, DD9.1, DD9.4, a pulse generator with a frequency of 7 kHz is made, which are used as clocks when outputting speech. The interface part of the circuit, which provides interfacing of the DD3-DD5 data switch with the vehicle's electrical system and bringing the input signals to TTL levels, is implemented on the DD1, DD2 and DA2 ICs. At the same time, operational amplifiers DA2.1, DA2.2 compare the temperature sensor signal with the settings set by resistors R7 and R11, a pulse shaper of normalized duration from the input ignition pulses is implemented on the DD2 chip, and the DD1 IC elements work as level converters and threshold elements. As can be seen from the diagram shown in Fig. 1, out of 18 input lines of the data switch DD3-DD5, only 10 are used to enter information. The remaining inputs are partly used as service inputs when setting up the device, and partly as a reserve for connecting additional sensors and developing the system. The audio path of the device includes a digital-to-analog converter on ICs DA3 and DA4, a 4-order Butterworth filter with a cutoff frequency of 3 kHz on operational amplifiers DA5.1, DA5.2 and a low-frequency amplifier DA6. The BSC power supply is made on an integrated stabilizer DA1, which generates a voltage of +5 V, and transistors VT1-VT3, which, together with the elements VD2-VD4 and C5, C6, provide polarity inversion and stabilization of the supply voltage of -5 V. Polarity inverter control pulses are used the CLK signal generated by the speech output clock. The device is configured using trimmer resistors:
Figure 2 shows a schematic diagram of one of the three identical channels of the lamp health monitoring unit in the rear lights. Given the parallel connection of the lamps of the same name, for the independence of control of each of them, the electrical circuit of the car is being finalized by introducing a diode decoupling of the lamps using VD1, VD3. After such refinement, the unit provides control of the operability of both lamps both on and off.
Until the voltage is applied to the lamps, the elements R1, VD2, LD1 and R3, VD4, LD2, together with the filaments of the corresponding lamps, form voltage dividers. Since the resistance of the lamp filaments is very small, the voltage drop across them is insignificant, the transistors VT1 and VT2 are closed and there is a logical "1" at the output of the node. In the event of an open circuit of any of the lamps, the corresponding transistor opens and a logical "0" is formed at the output of the node - a sign of lamp failure. When the lamps are on, i.e. when voltage is applied to them from the on-board network, their performance is monitored using current sensors. The sensors are KD reed switches with LD windings wound around them. The latter are connected in series with the controlled lamps, therefore, when current flows through them, the contacts of the reed switches close, shunting the base-emitter junctions of the transistors. Transistors VT1, VT2 are in the closed state, and the node output is in the logical "1" state. If any of the lamps fails, the current does not flow through the winding of the corresponding sensor, the reed switch contacts open, the corresponding transistor opens, and the state at the node output changes to the opposite. The BSC is connected to the vehicle electrical system in accordance with the diagram shown in Fig. 3 and operates as follows. After the supply voltage is applied to the device when the ignition is turned on, the scanning of the standard vehicle sensors involved in the system and the outputs of the lamp health monitoring unit begins. If within 5 seconds no sign of failure is detected on any of the input lines of the BSC, the scanning of the sensors is interrupted and the device proceeds to issuing the phrase "Happy journey", selecting the necessary digitized information from the speech ROM, after which it again returns to polling the sensors. If during the subsequent operation of the car a sign of failure occurs on one or more BSC input lines, the device will similarly issue the corresponding signaling phrase. At the same time, to ensure the reliability of the device and protection against false positives, the active level on the input lines of the BSC is perceived as a sign of failure only if it is present on the line continuously for 3 seconds. In most cases, the program provides for a double repetition of a phrase to increase the reliability of its perception. In addition, for the same purpose, each phrase is preceded by a tonal sound signal that attracts the driver's attention and prepares him to receive information. Structurally, the device is made in the form of two blocks: a BSC block located in the passenger compartment under the dashboard, and a lamp health monitoring unit installed near the rear lights. Author: S. Sukov; Publication: N. Bolshakov, rf.atnn.ru See other articles Section Automobile. Electronic devices. Read and write useful comments on this article. Latest news of science and technology, new electronics: Artificial leather for touch emulation
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