KR19990018240A - Up / down counter - Google Patents

Abstract

The present invention relates to an up / down counter which simultaneously performs up and down counts. In the related art, since a counter is configured by separately applying some bits of serial data, the count of a specific part is not completed until the count of the previous part is completed. Since it can start, the count time is delayed a lot. In view of the above problems, the present invention provides an 8-bit up counter which receives the clock signal and the power supply voltage and a 8-bit down counter which receives the clock signal by inverting the clock signal. The 8-bit down counter is carried by applying a reset signal to the bit cell signal that enables 8-bit or 16-bit dual mode and the carry signal output from the carry-out terminal of the 8-bit up counter. Input to the input terminal, 8-bit up counter up-counts the 16-bit lower bit and outputs it through the output terminal, and 8-bit down counter down-counts the 16-bit upper bit and outputs it through the output terminal. By counting up / down at the same time and counting 16 bits according to the control of the bit cell signal, counting is performed in parallel to count The effect that the time required to save and; Since several types of counts are performed at the same time, the number of counters used can be reduced, resulting in miniaturization, and the use of registers more efficiently.

Description

Up / down counter

The present invention relates to an up / down counter that simultaneously performs up and down counts, and more particularly, to an up / down counter that is suitable for a multi-counter system that simultaneously performs several types of counts using one type of counter. .

In general, a counter is used to count the number of occurrences of an event in almost all systems having digital logic or to generate a timing sequence for controlling a digital system. Such a counter will be described in detail with reference to the accompanying drawings. As follows.

FIG. 1 is a block diagram of a conventional 8-bit counter. As shown in FIG. 1, an 8-bit counter RIPPC8 is formed by connecting two 4-bit counters RIPCT4 in series.

That is, the output of the carry-out terminal CO10 of the 4-bit counter 10 is applied to the input of the carry-in terminal CI20 of the 4-bit counter 20.

At this time, the 4-bit counters 10 and 20 are clear terminals CLR10 and CLR20 that reset all flip-flops to '0' asynchronously, and the previous flip-flop. Carry-in terminals CI10 and CI20, which are set to '1' when a carry-out occurs, and clock terminals CLK10 and CLK20 to control all flip-flops to be synchronized in time. The data D [0: 3] and (D [4: 7]) are respectively input to perform a count operation according to the control signals of the load terminals LOAD10 and LOAD20 or the input data D [0: 3)). Output terminals Q10 and Q20 for transmitting (D [4: 7]) to output output data Q [0: 3] and Q [4: 7], respectively. When the carry signal is generated at the carry-in terminals CI10 and CI20, the carry-out terminals CO10 and CO20 are set to '1'.

2 is an internal circuit diagram of the 4-bit counter 10. As shown in FIG. 2, four flip-flops 1 to 4 are connected in series.

That is, the carry signal of the flip-flops 1 to 3 carry-out terminals CO1 to CO3 is applied to the input of the carry-in terminals CI2 to CI4 of the next flip-flops 2 to 4, and the flip-flop 1 Output data Q [0] to Q [2] output from the output terminals Q1 to Q3 of ˜3 are input to the count terminals CX2 to CX4 of the next flip-flops 2 to 4, respectively. To be authorized.

At this time, the power supply voltage VCC is input to the count terminal CX1 of the flip-flop 1, and is output from the carry-out signal and the output terminal Q4 output from the carry-out terminal CO4 of the flip-flop 4. The output data Q [3] is AND-combined through the AND gate AND1, and outputs the carry signal of the carry-out terminal CO10 of the 4-bit counter 10.

Referring to the operation of the conventional 8-bit counter configured as described above are as follows.

First, when '1' is input to the load terminals LOAD10 and LOAD20 of the 4-bit counters 10 and 20, the count operation is controlled so that the input data D [0: 7] is transmitted. And output through the output terminals Q10 and Q20.

On the other hand, when '0' is input to the load terminal LOAD10 of the 4-bit counter 10 and '1' is input to the carry-in terminal CI10, the rising edge of the clock signal input to the clock terminal CLK is applied. Perform the count operation in synchronization. Then, '0' is input to the load terminal LOAD20 of the 4-bit counter 20, and a carry occurs at the 4-bit counter 20, so that '1' is carried from the carry-out terminal CO10 to the carry-in terminal CI20. Is input, the count operation is performed in synchronization with the rising edge of the clock signal inputted to the clock terminal CLK.

However, the conventional counter operated as described above configures the counter by applying some bits of serial data separately, so that the counting of some specific bits can not start until the count of the first part is completed. There was a problem of this much delay, a waste of unused registers during multi-bit counts, and the need to reuse separate counters. This problem becomes more serious in terms of chip size or register efficiency when using a large number of counters with a large difference in the number of bits of the internal counters constituting the total counter.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an up / down counter capable of simultaneously performing up and down counts in parallel and selectively counting various types of bits. To provide.

1 is a block diagram of a conventional 8-bit counter.

2 is an internal circuit diagram of a 4-bit counter in FIG.

3 is a block diagram of a 16-bit up / down counter according to the present invention;

4 is an internal block diagram of an 8-bit up counter in FIG.

5 is an internal block diagram of an 8-bit down counter in FIG.

6 is an internal block diagram of a 4-bit down counter in FIG.

7 is an input / output waveform diagram of FIG. 3;

Explanation of symbols for the main parts of the drawings

NRIPCT8: 8-bit up counter DN_CT8: 8-bit down counter

INV1: Inverter OR1: Oragate

BIT_SEL: Bit cell signal CI: Carry-in terminal

CO: carry-out terminal

As described above, an object of the present invention is to connect an 8-bit up counter which receives a clock signal and a power supply voltage to a clock terminal and a carry-in terminal, and an 8-bit down counter which receives an input by inverting a clock signal to a clock terminal. The 8-bit down counter is applied by applying a reset signal to the terminal and ringing the carry signal output from the carry-out terminal of the 8-bit up counter and the bit cell signal enabling 8-bit or 16-bit dual mode. Input to carry-in terminal, 8-bit up counter up-counts 16-bit lower bit and outputs it through output terminal, 8-bit down counter down-counts 16-bit upper bit and outputs through output terminal 8-bit Up / down counting at the same time and at the same time to achieve 16 bits in accordance with the control of the bit cell signal to achieve the up / down count according to the present invention If described with reference to the accompanying drawings as follows.

FIG. 3 is a block diagram of a 16-bit up / down counter according to the present invention. As shown in FIG. 3, a clock signal and a power supply voltage VCC are input to the clock terminal CLK and the carry-in terminal CI, respectively. The 8-bit down counter DN_CT8 connected to the bit up counter NRIPCT8 and the clock terminal CLK by inverting the clock signal through the inverter INV1 is serially connected to reset signals RESET to each clear terminal CLR. Is applied and the carry signal OR1 is output from the carry signal CO of the 8-bit up counter NRIPCT8 and the bit cell signal BIT_SEL enabling 8-bit or 16-bit dual mode. ) And input into the carry-in terminal (CI) of the 8-bit down counter (DN_CT8), and the 8-bit up counter (NRIPCT8) up-counts the 16-bit lower bit and output terminal (Q [0: 7]). ) And the 8-bit down counter (DN_CT8) down counts the 16-bit high-order bit to output terminal (Q [0: 7)) and up / down counting by 8 bits at the same time, and 16 bits according to the control of the bit cell signal BIT_SEL.

4 is an internal block diagram of the 8-bit up counter NRIPCT8. As shown in FIG. 4, a clock signal is input to the clock terminal CLK and counted through an output terminal Q [0: 3]. Connect 4-bit counters (RIPCT4-1) and (RIPCT4-2) to be output in series, and input a clear signal to each clear terminal (CLR) and load terminal (LOAD) in common. The carry signal output from the carry-out terminal CO is input to the carry-in terminal CI of the 4-bit counter RIPCT4-2, and each data input terminal D [0: 3] is configured to be floated.

5 is an internal block diagram of the 8-bit down counter DN_CT8. As shown in FIG. 5, a clock signal is input to the clock terminal CLK and down counted to output the output terminals Q [0: 3]. Connect the 4-bit down counters (DN_CT4-1) and (DN_CT4-2) outputted in series, and input the clear signal to each clear terminal (CLR) and load terminal (LOAD) in common, and 4-bit down counter (DN_CT4-). The carry signal output from the carry-out terminal CO of 1) is input to the carry-in terminal CI of the 4-bit down counter DN_CT4-2, and each data input terminal D [0: 3] is floated. Configure.

6 is an internal block diagram of the 4-bit down counters DN_CT4-1 and DN_CT4-2. As shown in FIG. 6, the clock signals are inverted through the inverters INV2 to INV5, respectively. Four flip-flops 11-14 received in CLK) are connected in series.

That is, the carry signals of the flip-flops 11 to 13 carry-out terminals CO1 to CO3 are applied to the inputs of the carry-in terminals CI2 to CI4 of the next flip-flops 12 to 14, and the flip-flop 11 Output data Q [0] to Q [2] output from the output terminals Q1 to Q3 of ˜13 are inverted through the inverters INV6 to INV8, so that the flip-flops 12 to 14 of the next stage are inverted. It is applied to the input of the count terminals CX2 to CX4. At this time, the power supply voltage VCC is input to the count terminal CX1 of the flip-flop 11, and the carry-out signal and the output terminal Q4 output from the carry-out terminal CO4 of the flip-flop 14 are output. The output data Q [3] is AND-combined through the AND gate AND1, and outputs to the carry-in terminal CI of the 4-bit down counter DN_CT4-2 configured as described above. The operation of the up / down counter according to the present invention configured as described above will now be described with reference to the operation waveform diagram of FIG.

First, as illustrated in FIG. 7, the clock signal CLK is applied at a cycle of 100 ns, and the reset signal RESET is initially applied at about 62 ns to '0' while being maintained at '1'.

The bit cell signal BIT_SEL is maintained at '1' to simultaneously up / down count by 8 bits, and is applied as '0' from about 520 ns to count up 16 bits.

When this input is input to the up / down counter, the 8-bit up counter NRIPCT8 up-counts the low-bit outputs [0: 7] from '01' to 16-bit in synchronization with the rising edge of the clock signal CLK. At the same time, the 8-bit down counter DN_CT8 down counts the 16-bit upper bit output [8:16] in synchronization with the rising edge of the clock signal CLK.

In this way, up / down counting of 16 bits in parallel can reduce the overall count time.

In other words, 16 clocks are required to sequentially count 16 bits, but counting by 8 bits in parallel simultaneously reduces the count time to half.

On the other hand, as shown in Fig. 7, when the bit cell signal BIT_SEL is applied as '0' from about 520 ns, if no carry signal is output from the carry out terminal CO of the 8-bit up counter NRIPCT8, 8 bits are used. The down counter DN_CT8 is not operated.

Therefore, only the 16-bit lower bit output [0: 7] is counted up, resulting in a 16-bit counter.

The up / down counter according to the present invention, which operates as described above, has an effect of saving time required for counting by simultaneously counting in parallel; An effect of preventing waste of unused registers by selecting a number of bits to be counted so as to count bits having a small number of bits with a counter having a large number of bits when counting various bits; Since several types of counts are performed at the same time, the number of counters used can be reduced, resulting in miniaturization, and the use of registers more efficiently.

Claims (4)

Apply a reset signal to each clear terminal by connecting 8-bit up counter which receives clock signal and power supply voltage to clock terminal and carry-in terminal, and 8-bit down counter which inverts clock signal to clock terminal. Bit-cell signal that enables 8-bit or 16-bit dual mode and the carry signal output from the carry-out terminal of the 8-bit up counter are input to the carry-in terminal of the 8-bit down counter, and 8-bit The up counter counts the 16-bit lower bits and outputs them through the output terminal.The 8-bit down counter counts down the 16-bit upper bits and outputs them through the output terminal. And an up / down counter configured to count 16 bits according to the control of the bit cell signal. The 4 bit counter (RIPCT4-1) and (RIPCT4) according to claim 1, wherein the 8-bit up counter receives and counts a clock signal to the clock terminal CLK and outputs the counted output signal through the output terminal Q [0: 3]. -2) are connected in series, and a clear signal is commonly input to each clear terminal (CLR) and load terminal (LOAD), and a power supply voltage (VCC) is applied to the carry-in terminal (CI) of the 4-bit counter (RIPCT4-1). Input the carry signal from the carry-out terminal CO to the carry-in terminal CI of the 4-bit counter RIPCT4-2, and each data input terminal D [0: 3] is configured to be floated. Up / down counter characterized in that. The 8-bit down counter (DN_CT4-1) according to claim 1, wherein the 8-bit down counter receives a clock signal to the clock terminal CLK and down counts the output signal through the output terminal Q [0: 3]. (DN_CT4-2) is connected in series, but the clear signal is input to each clear terminal (CLR) and the load terminal (LOAD) in common, and the carry output from the carry-out terminal (CO) of the 4-bit down counter (DN_CT4-1) An up / down counter configured to input a signal to a carry-in terminal CI of a 4-bit down counter DN_CT4-2, and each data input terminal D [0: 3] to be floated. 4. The four flip-flops of claim 3, wherein the four-bit down counters DN_CT4-1 and DN_CT4-2 invert clock signals through the inverters INV2 to INV5 and are input to each clock terminal CLK. 11 to 14 are connected in series, but a carry signal from the flip-flops 11 to 13 carry-out terminals CO1 to CO3 is applied to the carry-in terminals CI2 to CI4 of the next flip-flops 12 to 14. The output data Q [0] to Q [2] output from the output terminals Q1 to Q3 of the flip-flops 11 to 13 are inverted through the inverters INV6 to INV9 to flip the next stage. It is applied to the inputs of the count terminals CX2 to CX4 of the flops 12 to 14, and the power supply voltage VCC is input to the count terminal CX1 of the flip-flop 11, and the carry-out of the flip-flop 14 is carried out. A 4-bit down counter configured in the same manner as above by AND combining the carryout signal output from the terminal CO4 and the output data Q [3] output from the output terminal Q4 through the AND gate AND1. Up / down counter, characterized in that configured to output to the carry-in terminal (CI) of DN_CT4-2.