JP2618876B2 - Service tone generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a service tone generator of a digital key telephone apparatus.

(Prior Art) As a conventional service tone generator, for example,
Some are as shown in the figure. As shown in the figure, the service tone generator comprises a tone control memory 101, an address step memory 103, an adder 105, a tone data memory 107, a comparator 109, a counter memory 111, and an increment circuit 113.

The tone control memory 101 periodically reads commands received from a central processing unit (not shown). The address step memory 103 stores the start address of each tone and the number of steps. That is, as shown in FIG. 5, when storing tone data having m kinds of frequencies, the start address and the number of steps are stored for each tone data 0, tone data 1,..., Tone data (m-1). I do. In this case, the start address of the tone data 0 is “00” and the number of steps is “l−1”. The start address of the tone data (m-1) is "(m-1)
0 "and the number of steps are" n-1 ". The upper address of these data addresses indicates the type of tone, and the lower address is used to identify the start address and the number of steps.

The adder 105 adds the output of the address step memory 103 and the output of the counter memory 111 to generate a tone data memory 107.
Send to Comparator 109 is address step memory 103
Number of address steps output from counter and counter memory 11
The display contents of 1 are compared, and if they are equal, the reset signal RS is sent to the increment circuit 113 to increment the increment circuit 113
Reset. The increment circuit 113 increases the contents of the counter memory 111. When the reset signal RS is sent from the comparator 109, the content is set to “0”.
The counter memory 111 has an increment circuit 113.
Is temporarily stored. Tone data memory 107 samples the service tones 8KH _Z μ / L conversion rule (CCIT
Stores 8-bit PCM data conforming to (T standard). The number of data samples depends on the tone frequency. FIG. 6 shows the stored contents of the tone data memory, which stores m types of tone data. The number of samples of tone data 0 is l, the number of samples of tone data 1 is K, and the number of samples of tone data (m-1) is h. The upper address of the tone data memory 107 indicates the type of tone, and the lower address indicates the number of steps.

In FIG. 4, reference numeral 115 denotes a data bus, and reference numeral 117 denotes a tone data bus.

Next, the operation of the service tone generator will be described. For example, when transmitting tone data 0, a command “00” is sent from the central processing unit (not shown) via the data bus 115. When the value of this command becomes the address of the address step memory 103, the start address “00” is read from the address step memory 103, and the adder
Entered in 105. At the next timing, the address of the address step memory 103 is incremented by 1. As a result, the number of steps “l−1” is read from the address step memory 103 and input to the comparator 109.

On the other hand, since the contents of the counter memory 111 are reset at the same timing, the contents of the counter memory “0” are reset.
"0" is input to the adder 105 and the comparator 109. The output of the address step memory 103 and the output of the counter memory 111 are added by the adder 105, and the added value is input as the address of the tone data memory 107. Therefore, the sample data 0 of the tone data 0 is output from the tone data memory 107.

On the other hand, the comparator 109 compares the number of steps output from the address step memory 103 with the contents of the counter memory 111, and when they are equal, the increment circuit 11
Reset 3. If the number of steps is larger than the contents of the counter memory 111, the counter value is incremented by 1 by the increment circuit 113, and this count value is stored in the counter memory 111. Therefore, the increment circuit 113 increments by one until the contents of the counter memory 111 become equal to the number of steps output from the address step 103, and this value is input to the adder 105, and the address of the tone data memory 107 is given. Data is read from the memory 107.

(Problems to be Solved by the Invention) However, the conventional service tone generating apparatus requires control from a central processing unit, is complicated, and requires a plurality of memories. There was a problem.

The present invention has been made in view of such problems,
It is an object of the present invention to provide a service tone generator which has a small number of integrated circuits and a simple apparatus, and requires control of a central processing unit.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention relates to a service tone generating apparatus which generates a plurality of types of service tones having different frequencies by assigning them to a plurality of time division time slots in each frame. The waveforms of the plurality of types of service tones having different frequencies are respectively sampled by predetermined sampling pulses, and the least common multiple of the respective sample numbers of the plurality of sampling data corresponding to the sampled service tones is obtained. Storage means for sequentially storing the sampling data at each address corresponding to each service tone, clock pulse generation means for generating a predetermined clock pulse corresponding to the sampling pulse, and a clock generated from the clock pulse generation means By counting the pulses A first counter that counts the number of steps for each time-division time slot and generates an upper address that sequentially specifies a storage location of each service tone stored in the storage unit; and a clock pulse generated by the clock pulse generation unit. And a second counter for generating a lower address for sequentially specifying a storage location of each sampling data of each service tone stored in the storage means, By sequentially reading out the sampling data stored in the storage means based on the upper address generated from the counter and the lower address generated from the second counter, a plurality of types of service tones having different frequencies are stored in each frame. Is assigned to each of a plurality of time-division time slots. To.

(Operation) According to the present invention, the upper address of the storage means is designated by the count value of the first counter, whereby the type of the service tone is switched, and the lower address of the storage means is determined by the count value of the second counter. Is designated, thereby sampling data of each service tone is read.

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

FIG. 1 is a block diagram showing the configuration of a service tone generator according to an embodiment of the present invention, and comprises a clock generator 151, a counter 153, a counter 155, and a tone data memory 157, as shown in FIG. Clock generator 151 is counter 15
Supply clock signal to 3,155. The counter 153 counts the clock signal and gives an upper address of the tone data memory 157 by incrementing for each time slot. The counter 155 counts the clock signal and increments by one frame to give a lower address of the tone data memory 157. The tone data memory 157 stores data obtained by sampling service tones of m types of frequencies on each type surface with a predetermined number of samples. In this case, if the least common multiple of the number of samples of each type is n for data sampled with a predetermined number of samples for each type, n pieces of sample data are stored for each tone data. FIG. 2 shows the stored contents of the tone data memory 157, where n sample data are stored for each of m types of tone data. The upper address of the tone data memory 157 indicates the type of tone, and the lower address indicates the number of data.

Next, the operation of this embodiment will be described. A clock signal is supplied from the clock generator 151 to the counter 153 and the counter 155. The counter 153 increments by one time stot and gives the upper address of the tone data memory 157. The counter 155 increments for each frame and gives the lower address of the tone data memory 157. Therefore, when processing the first frame, the output of the counter 155 is "0", and only the output of the counter 153 advances by one. Therefore, the address input to the tone data memory 157 is “00”, “10”... (M−1) 0 ”, and the data output from the tone data memory 157 is tone data 0.
Sample data 0, tone data 1 sample data 0,
... Sample data 0 of tone data (m-1).

When one frame is completed, the counter 155 advances, and the output of the counter 1556 becomes "1". Therefore, when processing the second frame, the addresses input to the tone data memory 157 are "01", "11" ..., "(m-1) 1".
Thus, the data output from the tone data memory 157 is sample data 1 of tone data 0, tone data 1
Sample data 1... Becomes sample data 1 of tone data (m-1).

Hereinafter, data is read from the tone data memory 157 in the same manner.

FIG. 3 shows tone data output from the tone data memory 157.

As described above, in this embodiment, a service tone can be generated without receiving a command from another central control unit,
Furthermore, the number of devices is small and the structure of the device can be simplified.

In this embodiment, a case has been described in which the number of time slots in one frame and the number m of tone types match, but these values do not necessarily need to match. If they do not match, the silence pattern is stored in the tone data memory.
This can be dealt with by writing to 157.

〔The invention's effect〕

As described above in detail, according to the present invention, it is possible to provide a service tone generator which has a small number of circuits and a simple structure, and does not require control of other central processing units.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a service tone generator according to an embodiment of the present invention, FIG. 2 is a diagram showing the contents stored in a tone data memory, FIG. 3 is a diagram showing a tone data bus-like data sequence, FIG. 4 is a block diagram showing the configuration of a conventional service tone generator, FIG. 5 is a diagram showing the contents stored in an address step memory, and FIG. 6 is a diagram showing the contents stored in a tone data memory. 151 clock generator, 153 counter, 155 counter, 157 tone data memory

Claims (1)

(57) [Claims] 1. A service tone generator for generating a plurality of types of service tones having different frequencies by allocating them to a plurality of time-division time slots in each frame. Sampled by the sampling pulse of
Storage means for obtaining the least common multiple of the number of samples of each of the plurality of sampling data corresponding to each sampled service tone, and sequentially storing the least common multiple sampling data at each address corresponding to each service tone; Clock pulse generating means for generating a predetermined clock pulse corresponding to the sampling pulse; counting the number of clock pulses generated from the clock pulse generating means to count the number of steps for each time-division time slot, and storing the number in the storage means A first counter for generating an upper address for sequentially specifying a storage location of each of the service tones, and counting the number of clock pulses generated from the clock pulse generating means to count the number of steps for each frame. Each sampling data of each stored service tone And a second counter for generating a lower address for sequentially designating the storage location of the second counter. The storage means based on an upper address generated from the first counter and a lower address generated from the second counter. A service tone generating apparatus characterized in that by sequentially reading stored sampling data, a plurality of types of service tones having different frequencies are assigned to a plurality of time division time slots in each frame and generated.