JPS5911133B2 - function generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a function generator whose frequency can be set arbitrarily.

Conventionally, there are sine wave, triangular wave, square wave, and various other function generators of this kind, but all of them are analog type using a dial scale for frequency setting, and the set frequency and the actual generated frequency are different. This method has disadvantages such as deviations between the two, and difficulty in increasing the frequency setting resolution to more than three digits.

In order to eliminate the above-mentioned drawbacks, the present invention attempts to provide a function generator that can generate an arbitrary function that is exactly the same as the set frequency by setting the frequency using a binary code and using a digital circuit. It is something.

An embodiment of the present invention will be described below with reference to the drawings.

That is, in FIG. 1, 1 is a variable frequency pulse generator;
A clock generator 6 that generates two-phase clocks CP4 and CP2 and a 4-bit binary counter (M53, 2
93), eight D-type flip-flops, and one OR gate. Now, if the memory capacity of ROM3 is 256 bytes of 8 bits, the binary counter 2
is 8 bits, and at the same time, if the minimum frequency is 1H2, the required frequency of each D-type flip-flop Q output in the variable frequency pulse generator 1 is DF8 is 256 x 2°H23.
DF7 is 256×21 Similar to H2, DF4 is 256×27
H2, and the frequency of the reference oscillator 5 is 256×29H2
becomes. The frequencies in each part of the variable frequency pulse generator 1 are CP=256×29Hz CP=256×28H2 CP22256×28H2 A12256×27Hz B=256×26Hz C1=256×25Hz D=256× 24H2 Al2256×23H2 B22256×22H2.

Next, the operation of the variable frequency pulse generator will be explained according to the timing chart shown in FIG.

That is, the output CP of the reference oscillator 5 is a pulse with a mark-space ratio of 1:1, and with CP as a reference, lock pulses CP and CP2 are generated as shown in FIG. A,,
Bl, Cl... are binary counters (M53
293), and each frequency is divided into %. D-type flip-flops DFl to DF8 are made of Al,
At the rising edge of Bl, Cl,..., the binary input F
7-FO is read and reset to the ``0'' level of CP2. The result can be expressed as a logical formula as follows. For example, to generate a 126Hz sine wave,
Then, by substituting this into the above equation (1), the 0R goot output Σ becomes.

Further, the number of bits of the binary counter 2 is determined by the memory capacity of the ROM 3.

For example, assuming a sine wave as shown in Figure 3, one period is divided into equal parts and the ROM address X = 1, 2...
256X and write the data as Sln-.2π, the binary counter 2 is 8 bits and can scan all addresses in the ROM 3.

Also, the value of Sin-X・2π is positive and negative 0 ゝ 2
Since the value is 56, negative values are expressed in two's complement, and if the data length is 8 bits, the data value will be ±127 or less.

X D(X)=[127s1n- ・2π] However, [ ] indicates 415 decimal places.

The table below shows a code table of data values to be written into the ROM 3, and the D-A converter 4 converts the data output of the ROM shown in the table below into an analog value, and
Generates a sine wave with a staircase approximation as shown in the figure.

Although a sine wave function has been described as an embodiment of the present invention, it goes without saying that any other function generator can be constructed, and the frequency can be varied in the range of 1 to 255H.
Although the variable frequency range has been described as up to z, the variable range can also be expanded by increasing the binary counter (M53293) of the variable frequency pulse generator 1 and changing the frequency of the reference oscillator.

As described above, according to the present invention, it is possible to provide a stable function generator with high frequency accuracy using binary input, and it is very effective as a process I/φ of a computer.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a timing chart thereof, and FIG. 3 is an output waveform diagram in the case of a sine wave function. In the figure, 1 is a variable frequency pulse generator, 2 is a binary counter, 3 is a ROM 14 is a DA converter, 5 is a reference oscillator, and 6 is a clock generator.

Claims (1)

[Claims] 1 Consisting of a clock generator, a binary counter, a D-type flip-flop, and an OR gate, the output of the binary counter is sent to the T input terminal of the D-type flip-flop, and the binary input command signal from the outside is sent to the D input terminal of the D-type flip-flop. a variable frequency pulse generator that controls a reference frequency by the binary input command signal by supplying the @Q@ output of each of the D-type flip-flops to the input terminals to the OR gate; and the variable frequency pulse generator. A binary counter that counts the output of the device, and an RO in which the value of one cycle of an arbitrary function is written as data using the value of this binary counter as an address.
A function generator comprising: M and a D-A converter that converts the digital output of this ROM into an analog value.