KR960008772Y1 - Musical scale frequency generating device of electronic musical instrument - Google Patents

Abstract

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Description

Scale generator of electronic musical instruments

1 is a circuit diagram of the present invention.

Figure 2 is a diagram showing the frequency and error of the endemic scale according to the present invention.

3 is a circuit diagram of a conventional scale frequency generator.

4 is (a) and (b) is the input / output relationship in case of C ₅ # scale in FIG.

5 is a waveform diagram read out and synthesized by the output generated by FIG.

* Explanation of symbols for main parts of the drawings

1: Input data register 2: Scale division ratio data ROM

3: adder 4: N counter

5: NS counter 6: Latch

7: Logic Gate 8: Spacing Counter

9: multiplexer 10: end gate portion

11: logic gate portion 12: inverter

The present invention relates to a musical instrument frequency generator of electronic musical instruments, and particularly, a Sento error in a pulse code modulation (PCM) sound source generator that sequentially reads data ROMs that sample musical instrument sounds to generate musical instrument sounds. The present invention relates to an electronic musical scale frequency generator capable of generating a scale frequency that is small in size and evenly distorts a waveform so that adverse effects caused by a DC-offset can be eliminated.

As shown in FIG. 3, a conventional scale frequency generator includes an input data register 31 for receiving and storing predetermined frequency and shift information from a control unit, not shown, and from the input data register 31. As shown in FIG. Scale division ratio data ROM 32 which generates division data (PN.PA) with the output as a bungee data, and division data PN and D flip-flop 37 outputted from the division ratio ratio data ROM 32; An adder 33 for ORing the data outputted from the output and outputting predetermined divided data N, a counter 34 for dividing the divided data N into a preset value by N, and the N counter. 34 outputs The output of the NS counter 35, which counts the signal until it reaches an NS value, the A counter 36 that counts until it reaches an A value, and the A counter 35 Signal and output of NS counter 35 The D flip-flop 37 which presets or resets the signal to and from the AND gate 38 by a logical result value, and the D flip-flop according to the final data load (FDL) and the reset signal state output from the controller. 37, which comprises a logic gate portion 39 for generating a reset signal. Referring to FIG. 4 (a) and (b) of FIG.

First, in the case of generating a C5 ^# scale of 1108.7HZ of the scale frequencies, for example, if the number of sampling periods (NS) of the highest octave of the musical instrument is 32, the output of the scale frequency generator is RP (Reading Pules). The frequency f _rp is 32 × 108.7 (HZ) = 35478.4 (HZ).

At this time, if the system clock frequency (f _CLR ) RK 8MHZ and the generated scale frequency is fo, its division data (PN) is Becomes

Therefore, in order to obtain an accurate scale frequency (fo), it is not an integer but must be divided by a real number including a decimal point.

However, since the N counter 34 can only be dispensed with an integer ratio, the NS counter 35 (in this case, NS = 32 is 32 counter) and 1 so as to equally divide to have a resolution up to the decimal point. A counter 36 with a limit value of A32 is provided, and when C5 ^# sound is generated, the dispensing data (N) is divided into 16 times at 225 and 16 times at 226 as shown in (A) of FIG. Thus, if 32 points, which are the number of samples of one period of the musical instrument, are read out, they are equivalent to those divided by 225, so that a very accurate scale frequency (fo) can be obtained.

That is, when address data for selecting the address of the scale division ratio data ROM 32 is output from the input data register 31, the division data PN is output as 225 from the scale division frequency data ROM 32. Since '1' is input from the D flip-flop 37 to the input terminal B of the adder 33, the frequency division data N is 226.

In addition, as the divided data N 226 is input to the N counter 34 as a preset value, the N counter 34 divides the clock frequency CK into 226 to generate a predetermined read pulse RP.

On the other hand, since predetermined division data PA 16 is output from the scale division ratio data ROM 2 to the A counter 36, the A counter 36 operates as a hexadecimal counter, and the NS counter 35 is NS = 32. It works as a counter.

In addition, when the scale generator starts to dispense, the output of the D flip-flop 37 is first. Since this becomes 'high', the N counter 4 divides 226, and the output of the N counter 34 Since the A counter 36 and the NS counter 35 perform the DOWN count each time a read pulse RP is generated, the A counter 34 divides the clock signal 225 after 16 counts.

Also, when the N counter 34 dispenses 225, its output terminal A read pulse RP is generated at the output of the NS counter 35 when the read pulse RP is generated 16 times. This causes the D flip-flop 37 to be reset so that the N counter 34 repeats the process of counting 226.

Therefore, equivalently, after the read pulse (RP) output of the N counter 34 is generated by 32 times the number of samples of one period of the musical instrument, the clock frequency is divided by 225.5 equivalently.

That is, if the two-module counting is not performed in this way, since the frequency of generation (fo) is an integer division data (PN), it is possible to divide the clock frequency (f _CLR ) by the common multiple of NS (here 32). Therefore, the clock frequency f _CLR can be _divided by any integer value.

In other words, when the C5 ^# scale is generated, the first 16 times divide 226 clock signals and the remaining 16 times 225 divide to achieve an equivalent 225.5 division, but the instrument sound wave ROM is read by the reading pulse (RP). If the waveform is generated by reading sequentially, as shown in FIG. 5, the time (t _P , t _N ) of the positive (+) half-cycle orphan-negative (-) half-cycle is different from each other. Since the area of the polar half period is larger than the area of the negative half period, the average value has a positive offset, and when a sound is generated through the acoustic system, unwanted clock clicks are generated and the beautiful sound cannot be generated. There was a powder point.

The present invention was devised to solve such a conventional problem, and by adding a multiplexer, a spacing counter and a plurality of logic elements to a conventional scale generator, the scale frequency of an extremely small sento error without increasing the clock frequency of the system In addition, it is possible to eliminate the distortion and direct current offset of the instrument sound waveform, which is a conventional problem, without adding a large hardware device, and in particular, the entire circuit is composed of digital circuits to enable integration. An object of the present invention is to provide an electronic musical instrument frequency generator capable of lowering the production cost. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the structure of the present invention is composed of an input data register 1 for receiving and storing frequency and shift information from a control means, and an output from the input data register 1 as address data. An adder for generating the divided data N by logically combining the outputs of the divided frequency data ROM ROM 2 for generating the divided data PN and the interval data INTD and the outputs of the divided data PN and the end gate portion 10. (3), an N counter 4 for dividing the clock N by receiving the divided data N generated from the adder 3, and counting the clock to NS whenever the output of the N counter 4 occurs. And the NS counter 5 generating an output pulse every time it is NS, and the data INTD which is the output of the scale division ratio data ROM 2 whenever the output of the N counter 4 is generated. Spacing counter that counts output of N counter 4 as set value (8), a multiplexer 9 for selecting predetermined data (FFH or 01H) under the control of code data which is output from the scale division ratio data ROM 2, and an output of the multiplexer 9; An AND gate portion 10 for supplying or interrupting one input terminal of (3), a latch portion 6 for generating a signal for determining the operation of the AND gate portion 10, the interval counter 8, and an N counter (4), the logic gate portion 11 for controlling the latch portion 6 according to the signals input from the NS counter 5 and the control means, and the output from the control means to the logic gate portion 11; And a logic gate 7 for providing the FDL signal and the reset signal as information, wherein the interval counter 8 is configured to count the signal inverted by the inverter 12 of the output of the N counter 4. It features.

The logic gate part 11 inputs the output signals of the N counter 4 and the interval counter 8 to generate a first signal for generating a preset signal PS for the operation of the latch part 6. (111), the second or gate 112 that takes the inverted signal of the interval counter 8 and the output signal of the N counter 4 as inputs, the output of the second or gate 112 and the NS counter And an AND gate 113 for generating the reset signal RS of the latch unit 6 by ANDing the output signal of (5) and the output signal of the logic gate 7.

If described with reference to Figure 2 the effect of the present invention configured as described above.

For example, in the case of generating the C5 ^# scale frequency, for example, the frequency division frequency (N) is divided into two values of C5 ^{# in} the case of N = 225 and 226. When distributing the distortion of the waveform by distributing 16 times purely 226 from the beginning as in the prior art, and then distributing 226 and 225 at 32 equal intervals within one cycle of the instrument sound waveform without dispensing 16 times to 225 afterwards. In addition, direct current offset should be offset.

Therefore, in the case of C5 ^# , the 226 division is 16 times and the 225 division is 16, so the interval data (INTD) becomes NS / 16 = 2, and this interval data (INTD) becomes the preset value of the interval counter (8). The interval counter 8 operates as a binary counter, and its output stage is used for 32 samples of one cycle of the musical instrument. The predetermined pulse is generated 16 times.

Accordingly, the output of the interval counter 8 is not generated. When only the output of the N counter 4 is generated, 225 divisions are performed, and predetermined pulses are simultaneously output from the N counter 4 and the interval counter 8. In this case, 226 divisions are performed.

That is, since the 225 and 226 divisions are alternately performed, the distortion of the waveform is dispersed so that the instrument sound waveform of the entire cycle has the correct scale frequency, the waveform distortion is small, and the average value is ø so that no DC offset is generated.

In addition, the standard frequency according to each scale, the division data (PN), the sign data, and the interval data (INTD) for generating the same are shown in the diagram shown in Fig. 2, so the generated frequency f'o is very small. It can be seen that the error.

For example, in FIG. 2, in the case of the C scale, the division data PN is 239 and the sign data is '1', so the multiplexer 9 controlled by the sign data selects the input terminal A. Since 'FFH' is a two's complement of '01H', this 'FFH' value is applied to the input terminal B of the adder 3 through the AND gate portion 10 so that the adder 3 operates the subtractor. As the interval data (INTD) is '10', the frequency of the dispense data (PN-1), that is, 238, is outputted. During the 32 times, which is the number of samples (NS) in one cycle of the musical instrument, 238 divisions are performed three times at equal intervals.

Therefore, as in the prior art, 239 divisions of 29 times are performed continuously from the first starting point of one period of the musical instrument sound, and 239 and 238 divisions are evenly distributed within one cycle of the last three times.

In addition, in the case where the multiplexer 9 is provided in FIG. 1, it may be necessary to dispense one more value (PN + 1) than the frequency division data (PN) depending on the scale, and also to dispense one small value (PN-1). Is there to select it properly.

In addition, when predetermined frequency and shift data are inputted to the input data register 1 from the control means not shown, selected data is output from the scale-division ratio data ROM 2 in which each data of FIG. , The interval counter 8 and the multiplexer 9 are inputted. If the A ^# scale is selected, the interval counter 8 operates as a decimal counter, and the multiplexer 9 has a code data of '0'. Select '01H'.

On the other hand, the latch portion 6 composed of the D flip-flop causes the output Q to be 'high' each time an output is generated in the interval counter 8, so that the output of the AND gate portion 10 is the multiplexer 9 Output is '01H', and the N counter 4 performs PN + 1 division.

In addition, when the output of the interval counter 8 is not generated, the output Q of the latch unit 6 is always 'low', so that the output of the end gate 10 is 'low', and the output of the adder 3 is output. The divided data N, which is the data, is equal to the divided data PN.

The NS counter 5 is for counting 32, which is the sampling number NS within one period of the musical instrument, and performs a falling coefficient every time an output pulse of the N counter 4 is generated. 'N' generates a predetermined output signal, so that the latch unit 6 resets its output Q to '0', so that the N counter 4 always divides the frequency with the divided data PN. .

As described above, according to the present invention, it is possible to generate scale frequencies with extremely small send error without increasing the clock frequency of the system. The whole circuit is made up of digital elements, which makes it possible to integrate, which not only simplifies the process and lowers the production cost of the product, but also outputs these musical sounds.

Claims (1)

In an apparatus for generating a system frequency by dividing a system clock, an input data register (1) for receiving and storing frequency and shift information, and an output from the input data register (1) as a bungee data, PN) and interval data INTD; a scaler division ratio data ROM 2, an adder 3 for generating division data N by adding outputs of the division data PN and the end gate portion 10; When the output of the N counter 4 is generated and the N counter 4 divides the clock by receiving the divided data N, the clock is clocked to NS, which is the number of sample points of one cycle of the highest octave of the instrument sound. The NS counter 5 generates an output pulse every time it is counted to NS, and receives the data INTD, which is the output of the scale division ratio data ROM 2 whenever the output of the NS counter 5 is generated, and frees it. The output of the N counter 4 is counted as a set value. A multiplexer 9 for receiving predetermined data (FFH or 01H) by receiving a coded signal output from the scale counting ratio data ROM 2, a coded division ratio data ROM 2, and an output of the multiplexer 9; And an gate portion 10 for supplying or blocking the input to one input terminal B of the adder 3, a latch portion 6 for generating a signal for determining the operation of the AND gate portion 10, and the N; And a logic gate portion 11 and a logic gate portion 11 for generating a signal for controlling the latch portion 6 in accordance with a signal input from the NS and the interval counters 4, 5, and 8 and the control means. And a logic gate 7 for providing an FDL signal and a reset signal, wherein the interval counter 8 converts the output of the N counter 4 by the inverter 12. It is configured to count so that two dispensing data (N) are used to perform dispensing alternately at equal intervals. Scale the frequency-generating unit of the electronic musical instrument as ranging.