JPH06282348A - Serial clock generating circuit - Google Patents

Abstract

PURPOSE:To provide a serial clock generating method capable of simply and easily obtaining serial clocks with arm optional pattern by using general purpose elements. CONSTITUTION:This serial clock generating circuit is provided with an oscillator 10 for oscillating a pulse string with fixed frequency, a counter 20 for counting up output pulses outputted from the oscillator 10 and a memory device 30 whose respective address ports are respectively connected to corresponding output ports of the counter 20. The memory device 30 is characterized by storing clock pattern data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for generating a serial clock which is supplied to a serial device which sends serial data.

[0002]

2. Description of the Related Art Since this type of serial clock needs to generate a serial clock having a pattern required by the serial device, conventionally, a dedicated clock generating circuit (chip) has been prepared for the serial device.

[0003]

For this reason, the clock generation circuit is expensive, and when the required serial clock pattern is complicated, a commercially available one will not suffice and must be manufactured in-house. Goodbye, but there was a problem that it took a lot of time and effort.

The present invention has been made to solve this problem, and an object thereof is to provide a serial clock generation circuit which can easily and easily obtain a serial clock of an arbitrary pattern by using a general-purpose chip. To do.

[0005]

In order to achieve the above object, the present invention provides an oscillator for oscillating a pulse train having a constant frequency,
The counter that counts the output pulse of the oscillator and the memory device in which each address port is connected to the corresponding output port of the counter are provided, and the memory device stores the clock pattern data.

[0006]

According to the present invention, a serial clock having a desired pattern can be obtained by using extremely general-purpose elements such as an oscillator, a counter and a memory device.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 10 is an oscillator (OSC),
Reference numeral 20 is a counter (UP counter in this example), and 30 is a memory device (EPROM in this example) storing clock pattern data.

The oscillator (OSC) 10 oscillates a pulse P having a predetermined frequency, and the UP counter 20 counts this pulse P. The count output port Q ₀ of the counter 20,
Since Q ₁ to Q _N is connected to the address port A _0, A ₁ ~A _N memory device 30, memory contents of the address (data), the data output port D ₀ of the memory device 30, D ₁ ~ It is output from D _N.

Now, the EPROM 30 is a 4-bit device, and the data at addresses A _{0 to} A ₃ is (0001),
If (0100), (0110), and (1001), for example, the output of the output port D ₀ is the counter 20
Every time the pulse P is counted (1 → 0 → 0 → 1 → 1 ...
, And the output from the output port D ₁ is (0 → 0 → 1 → 1 → 0 ...) every time the counter 20 counts the pulse P.
・, And the output port D ₂ is (0 → 1 → 1 → 0 → 0)
...), the output port D ₃ is (0 → 0 → 0 → 1 → 0.
..), and different serial clock patterns can be obtained from the output ports D ₀ and D _{1 to DN} .

In this embodiment, the frequency of the serial clock can be easily changed by changing the oscillation frequency of the oscillator (OSC) 10, and a plurality of standardized memory devices in which different clock pattern data are written are prepared. In other words, by replacing the memory device 30, a serial clock having a desired pattern can be obtained.

In this embodiment, clock data is written in a memory device, and a counter for counting output pulses of an oscillator is used. The address of the memory device is designated to obtain a serial clock. A serial clock having a desired pattern can be easily obtained only by using elements and devices.

As the memory device 30, a mask ROM, a one-time PROM, an E ² PROM or the like may be used.

If a UP / DOWN counter is used as the counter, a serial clock having a reverse pattern can be obtained.

[0015]

As described above, the present invention makes it possible to easily obtain a serial clock having a desired pattern at low cost by using general-purpose elements and devices.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

[Explanation of symbols]

 10 oscillator 20 UP counter 30 memory device

Claims (1)

[Claims] 1. An oscillator for oscillating a pulse train having a constant frequency, a counter for counting output pulses of the oscillator, and a memory device in which each address port is connected to a corresponding output port of the counter, respectively. The memory device is a serial clock generation circuit that stores clock pattern data.