JPH0535473B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a barcode reading device that reads a barcode symbol with a barcode scanner and decodes its serial data.

[Prior Art] In recent years, data processing devices equipped with bar code symbol reading devices have appeared in order to simplify and speed up data input.

Traditionally, this type of barcode reading device uses a decoder that utilizes the interrupt function of a data processing device for speed, flexibility, and cost.In order to achieve a good decoder, the software must be carefully designed. It had become something that was designed.

This barcode decoding and its processing contents will be explained.

In binary level barcode symbols, the logical value is determined based on the time width (hereinafter referred to as element width) of the pulses serially output by the barcode scanner, and a character bit image is constructed based on the logical value. . Here, a pulse having an element width corresponding to a logic "1" is called a wide element, and a pulse having an element width corresponding to a logic "0" is called a narrow element. A threshold is set for the logical value, and if the element width is larger than that value, it is set to "1", and if it is smaller, it is set to "0". A simple method for setting the threshold is to set the threshold TH to the middle between the wide element width W and the narrow element width N. In other words,
All you have to do is calculate TH=(W+N)÷2. Here, if we give W the latest wide element width and N the latest narrow element width, and modify the threshold TH for each pulse input, we can compensate for the acceleration caused by the operator when scanning the barcode. can be done.

When a barcode symbol is scanned by a barcode scanner, wide/narrow elements are repeatedly received serially, converted into logical values, and stored. When a predetermined number of elements are received, the bit image data for one character is completed, and thereafter the bit image is code converted and start character and stop character detection processing is performed.

The above-mentioned processing needs to be processed at a sufficiently high speed so as not to cause problems with the maximum value of data input by barcode scanning (scanning at the maximum speed when the element width is the minimum). It won't happen. Furthermore, in order to deal with the fact that the time interval between element pulses is becoming shorter due to the higher density of barcode modules or faster scan speeds, it is desirable to have a means to achieve the above-mentioned processing faster and in a shorter time. It is rare.

FIG. 2 shows a block diagram of a data processing device incorporating a conventional bar code decoding interface. This data processing device is an execution unit 1
0, program memory 20, data memory 30,
An edge detection unit 40 that detects the rising and falling edges of the pulse of signal 1 from the barcode scanner and outputs an edge detection signal 2 synchronized with this; a timer that measures and determines the time interval of the scanner signal;
It consists of an event counter 50 and an interrupt control section 60, each of which is interconnected via an internal data bus 70.

The execution section 10 has a program counter 11, a program status word 12, and a general-purpose register set 13, reads out instruction codes from the program memory 20, executes them, and stores the processed data in the data memory 30. On the data memory 30, the latest wide count number storage area 31, the latest narrow count number storage area 32, and the number of elements per character of the barcode symbol are set, and the rising edge and rising edge of the pulse of the barcode scanner signal 1 are set. An element count storage area 33 that counts down and holds the value every time a falling edge detection signal 2 is generated, and stores logical values corresponding to wide/narrow elements from LSB to the right every time one element data is received. A bit image storage area 34 for storing data, a character data storage area 35 for storing bit image data each time one character is completed, and a stack area 36 are allocated. When the interrupt control unit 60 receives the edge detection signal 2 output from the edge detection unit 40, it notifies the execution unit 10 of the interrupt. The timer/event counter 50 includes an interval register 51 that sets the timer interval, a count register 55 that is initialized every time the edge detection signal 2 is received and starts counting up the counter, and a value of this count register 55 that is stored in the interval register 51.
The comparator 52 generates the interval control signal 3 by detecting that the edge detection signal 2 has been exceeded, the interval signal flag 54 is set by the interval control signal 3, and the contents of the count register 55 are read every time the edge detection signal 2 is received. It consists of a capture register 56 for storing data.

Next, a processing procedure for interrupt processing generated by edge detection signal 2 will be explained.

When the edge detection signal 2 is output, the count value of the count register 55 of the timer/event counter 50 is stored in the capture register 56,
The count register 55 is initialized and starts counting again. In addition, the data processing device starts interrupt processing and uses a program counter 11,
The contents of the program status word 12 and general-purpose register set 13 are temporarily saved to the stack area 36 on the data memory 30. The interval signal flag 54 is set when the value of the count register 55 that started at the time of the previous edge detection interrupt exceeds the threshold value set in the interval register 51. Therefore, if the interval signal flag 54 is set, This means that the pulses that occurred before the current edge detection interrupt occurred were logic "1". Similarly, if interval signal flag 54 is not set, it means that the pulse was a logic "0".

If this interval signal flag 54 is checked and it is set, the content of the capture register 56 is set as the latest wide element width, the content of the latest wide count storage area 31 is updated, and the program status word 12 is updated. Set the carry flag. If the interval signal flag 54 is not set, the content of the capture register 56 is set as the latest narrow element width, the content of the latest narrow count storage area 32 is updated, and the carry flag of the program status word 12 is updated. Reset. Subsequently, the contents of the latest wide count storage area 31 and the latest narrow count storage area 32 are added and divided by 2, and the result is set in the interval register 51 as a threshold correction value.

Next, the contents of the bit image storage area 34 are read out to an arithmetic and logic unit (hereinafter referred to as ALU), rotated to the right together with a carry flag, and returned to the image storage area 34 again.
Through this process, a bit image is stored right-aligned from the LSB of the decoded bits every time one element data is received.

Next, the contents of the element count storage area 33 are read out, 1 is subtracted, and then it is checked whether the result is 0 or not. If the result is not 0, it means that the bit image for one character is incomplete, and the result of subtracting by 1, that is, counting down, is stored in the element count number storage area 33 again. Thereafter, the contents saved in the stack area 36 are stored in the program counter 11 and program status word 1, respectively.
2. Return to general register set 13 and return to main routine from interrupt processing.

Furthermore, if the result of subtracting 1 from the contents of the element count number storage area 33 is 0, it means that the bit image for one character has been completed, and the one character data reception process is started and the bit image storage area 34 is The contents are read out and stored in the character data storage area 35 as completed character data. Then, the number of elements per character of the barcode symbol (for example, 3of9) is stored in the element count storage area 33.
If it is a code, 9) is stored as the initial value.

Processing such as converting the completed character data into ASCII code according to the encoding format of the barcode, and detecting margins, start characters, and stop characters is normally performed, but here is a detailed explanation. is omitted. Thereafter, the contents saved in the stack area 36 are returned to the program counter 11, program status word 12, and general-purpose register set 13, respectively, and the interrupt processing returns to the main program processing.

[Problem that the invention seeks to solve]

In high-speed scanning of high-density barcodes, the element pulse time interval is several hundred microseconds, and it is necessary to perform barcode decoding processing that is sufficiently faster than this, but conventional software processing using interrupts is not possible. The scanning speed may be limited by the processing power of the data processing device. Furthermore, in order to realize a barcode decoder with higher resolution, it is desired that the total processing speed be increased. However, in interrupt software processing by a conventional data processing device, the execution unit status and data are saved to or returned from the stack area at the start of interrupt processing, instruction fetch and instruction decoding during processing execution, and instruction decoding during memory access. Setting the address to the memory pointer of the memory, temporarily loading the data in the memory into the general-purpose register, data transfer and calculation,
Overhead always accompanies the execution of software processing, such as judgment processing, and is one of the factors that inevitably limits the scanning speed.

The purpose of the present invention is to eliminate the above-mentioned drawbacks associated with interrupt-based software processing in barcode decoders, and to add dedicated hardware using a random logic circuit that automatically updates thresholds, generates serial data, etc. without any
An object of the present invention is to provide a barcode reading device that realizes serial data reading processing from pulse information output from a barcode scanner by effectively utilizing the hardware of a data processing device.

[Means for solving problems]

The barcode reading device of the present invention includes a pulse detection section that detects an input barcode pulse and generates a request for decoding the barcode pulse, and a counting operation that starts counting in synchronization with the pulse detection of this pulse detection section. A pulse period measurement section that measures the pulse period, a memory section that stores programs and various data, and a central processing section that selectively executes decoding processing based on processing requests from the pulse detection section and normal instruction processing based on the program. In the barcode reading device, the decoding process of the central processing unit is performed when the pulse detection unit generates the processing request, the program counter and the program inside the central processing unit related to the execution of the command processing are executed. It is activated while holding the state of the status word, and converts the pulse period information from the pulse period measuring section into character bit information using data in a group of automatic transfer control registers provided in the memory section and which can be arbitrarily written by software. It is characterized in that it is processed so as to convert it into .

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. The execution unit receives I/O from the I/O request control unit 80.
An I/O controller that receives signals from the O processing execution request line 6 and the I/O processing execution mode specification line 7 to control the operation of the execution section.
O request receiving section 81, program memory 20 that stores programs such as the main program and interrupt processing program, data memory 30 that holds processing data, program counter 11 that indicates the address of the next program to be executed, and the overall operation of the execution section. A program status word 12 indicating the status, a general-purpose register set 13 used for storing various data and specifying memory addresses, etc., an arithmetic logic unit (ALU) 14 with arithmetic and logic operation functions,
Instruction register 1 that holds instructions to be executed
5. It is composed of an instruction decoder 16 that generates various control signals according to the contents of the instruction register 15, and an execution control section 17 that controls the operation of the entire execution section based on the output of this instruction decoder 16. The timer event counter 50 includes an interval register 51 that sets the timer interval, a count register 55 that is initialized every time the edge detection signal 2 is received, and starts counting up, and the value of this count register 55 is the value of the interval register 51. It is detected that the interval has exceeded the interval control signal 3.
, an interval signal flag 54 that is set by the interval control signal 3, and a capture register 56 that stores the contents of the count register 55 each time the edge detection signal 2 is received. . In addition, the data memory 30
includes the latest wide count register 91, the latest narrow count register 92, an element counter 93 that counts each generation of edge detection signal 2 as the number of times one element data is received, an interval register pointer 94 that specifies the interval register 51, and the interval register 92. signal flag 5
4, a capture register pointer 96 that specifies the capture register 56, and a logical value corresponding to the wide/narrow element each time one element data is received.
An automatic transfer register group 90 is set for automatic data transfer processing, which consists of a bit image register 97 that is stored from LSB to the right and can be read and written arbitrarily by software, and furthermore, a character data storage area 35 and a stack area 36 are allocated. It is being

The edge detection section 40 detects the rising and falling edges of the barcode scanner signal 1, and sends an edge detection signal 2 synchronized thereto to the I/O request control section 80.
is output to the timer/event counter 50.
The I/O request control unit 80 receives the edge detection signal 2 as an I/O request, and controls the I/O process execution request line 6 and the I/O process execution mode designation line 7.

When the edge detection section 40 outputs the edge detection signal 2 to the timer/event counter 50, the count value of the count register 55 is stored in the capture register 56, and the count register 55 is initialized and starts counting again. The interval signal flag 54 is set by the interval control signal 3 when the count of the count register 55 exceeds a threshold value set in the interval register 51. Furthermore, when the edge detection signal 2 is simultaneously input to the I/O request control section 80, the I/O request control section 80 outputs the address of the automatic transfer register group 90 to the internal data bus 70. In addition, the I/O processing execution request line 6 and the I/O
The signal on the O-processing execution mode designation line 7 is set to high level.

In the figure, the execution unit normally transfers the instructions stored in the program memory 20 corresponding to the contents of the program counter 11 to the instruction register 15,
An instruction decoder 16 and an execution control unit 17 perform various controls and realize instruction processing such as data transfer and calculation. Each time one instruction is executed, the value of the program counter 11 is updated to the address of the next instruction to be executed, and the above operation is repeated to execute the program. The I/O request reception unit 81 samples the I/O processing execution request signal 6 every time an instruction is completed, and when the signal is at a low level, continues execution of the program.

Next, the operation when an I/O request occurs will be explained. The I/O request receiving unit 81 samples the I/O processing execution mode designation signal 7 at the same time as training that the I/O processing execution request signal 6 is at a high level, and if it is at a high level, it accepts the I/O request. Part 81
is determined to be a 1-element data reception processing request, and a 1-element data reception processing code is forcibly set in the instruction register 15. Execution control unit 17
prohibits address updating of program counter 11, and then updates program counter 11, program status word 12, and general register set 13.
Start the following process while retaining the value of .

(1) The I/O request control unit 80 is connected to the internal data bus 70
The execution control unit 17 reads the address of the automatic transfer register group 90 output above.

(2) The execution control unit 17 reads the interval signal flag 54 specified by the flag pointer 95,
Check logical value.

(3) If the interval signal flag 54 is set, it is set to logic "1" and the capture register 5 specified by the capture register pointer 96 is set.
6 contents to the latest wide counter register 91
and further bit image register 97
Read the contents to ALU14 and set “1” to MSB
is input and the right-shifted result is returned to the bit image register 97 again. On the other hand, if the interval signal flag 54 has been reset, it is set to logic "0" and the capture register pointer 9
Transfers the contents of the capture register 56 specified by 6 to the latest narrow count register 92,
Furthermore, the contents of the bit image register 97 are read out, "0" is input to the MSB, and the right-shifted result is returned to the bit image register 97 again.

(4) Check the contents of the latest wide count register 91 and the latest narrow count register 92.
The result of reading and adding to the ALU 14 and dividing by 2 is transferred to the interval register 51 specified by the interval register pointer 94 as a threshold correction value.

(5) Transfer the contents of element counter 93 to ALU 14
If it is not 0, the result is returned to the element counter 93, the one element data reception process is completed, and the interrupted program process of reading and executing the instruction word based on the program counter 11 is restarted. .

(6) When the content of the element counter 93 is subtracted by 1 and the result becomes 0, the ALU 14 automatically sends the 1-character data reception interrupt control signal 5 to the I/O
It is output to the request control section 80. This I/O request control unit 80 outputs a character data reception interrupt processing address to the internal data bus 70,
The signal on the I/O process execution request line 6 is set to high level, and the signal on the I/O process execution mode designation line 7 is set to low level. The I/O request reception unit 81 determines this as a 1-character data reception interrupt processing request, and forcibly sets a 1-character data reception interrupt processing code in the instruction register 15.
The execution control unit 17 also controls the program counter 1.
1, and then program counter 11 and program status word 1.
2 and the general-purpose register set 13 are saved in the stack area 36 on the data memory 30. The execution unit outputs the 1-character data reception interrupt processing address that the I/O request control unit 80 outputs onto the internal data bus to the program counter 11.
By transferring the data to , the one character data reception processing program is started.

The contents of this one-character data reception process are the same as the one-character data reception process in the conventional example, in which the contents of the bit image register 97 are read out, stored in the character data storage area 35 on the data memory 30, and the counter 93
The number of elements per character of the barcode symbol is set as an initial value. After this, the completed character data is converted into ASCII code according to the encoding format of the barcode,
Processing such as margin or start character and stop character detection is normally performed, but detailed explanation thereof will be omitted.

After completing this series of processing, the data memory 3
By returning the data saved in the stack area 36 above 0 to the program counter 11, program status word 12, and general-purpose register set 13, the interrupted main program processing is returned to.

〔Effect of the invention〕

As explained above, the present invention processes the processing that occurs when receiving an output pulse of a barcode scanner, that is, the judgment of the logical value of the received pulse, while correcting the threshold, accepts the reception a predetermined number of times, and completes the reception of data for one character. Barcode pulse reception processing is performed without overhead due to software interrupts, and program execution is interrupted by a request that occurs when receiving an output pulse from the barcode scanner.
Stops the CPU's normal program execution operation,
While retaining CPU status and data,
This is realized by the CPU itself performing barcode reception processing, eliminating the need for special external hardware and eliminating the need for branching and return processing to interrupt vectors, program counters, and program processing, which were inherent in conventional interrupt processing. It is possible to significantly reduce the time spent saving and restoring status words and general-purpose registers, fetching and decoding individual instructions, setting addresses to memory pointers when accessing memory, and processing data using general-purpose registers. Furthermore, since a 1-character data reception interrupt processing request is generated only when 1 character of bit image data is completed by 1-element data reception processing, the number of interrupt processing activations is greatly reduced, and the drop in CPU execution efficiency is minimized. It has the effect of reducing

This reduction in data processing time minimizes the limitations on the barcode scanning speed, so as the scanning speed increases, for example, in the case of a laser scanning method, the By increasing the number of scans, it is possible to improve the reading rate, and at the same time, it is now possible to handle the higher density of barcode symbols that accompany larger amounts of information, making it possible to increase the resolution of the system. .

As described above, the barcode reading device of the present invention has
It is possible to provide reception data processing means most suitable for reception processing of output pulses of a barcode scanner, and the practical effect is extremely high.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figure is a block diagram of a conventional barcode reading control device. In the figure, 1...barcode scanner signal,
2... Edge detection signal, 3... Interval control signal, 5... Interrupt control signal, 6... I/O processing request signal, 7... I/O processing designation signal, 10... Execution unit, 11... ...Program counter, 12...Program status word, 13...General purpose register set, 14...Arithmetic logic unit (ALU), 15...Instruction register, 16...Instruction register, 17...Execution control unit, 20... ...Program memory, 30...Data memory, 31...Latest wide count number storage area, 32...Latest narrow count number storage area, 33...Element count number storage area, 34...Bit image storage area, 35 ... Character data storage area, 36 ... Stack area, 40 ... Edge detection section, 50 ... Timer/event counter,
51...Interval register, 52...Comparator, 54...Interval signal flag, 55...
Count register, 56...Capture register, 60...Interrupt control unit, 70...Internal data bus, 80...I/O request control unit, 81...I/
O request receiving unit, 90... automatic transfer register group, 9
1...Latest wide count register, 92...
These are the latest narrow count register, 93...element counter, 94...interval register pointer, 95...flag pointer, 96...capture register pointer, 97...bit image register.

Claims (1)

[Claims] 1. A pulse detection section that detects an input barcode pulse and generates a decoding processing request for this barcode pulse, and a pulse period that starts counting operation in synchronization with the pulse detection of this pulse detection section and measures the pulse period. A barcode reading device comprising a measurement section, a memory section that stores programs and various data, and a central processing section that selectively executes decoding processing according to a processing request from the pulse detection section and normal command processing according to the program. In the decoding process of the central processing unit, when the pulse detection unit generates the processing request, the state of a program counter and a program status word inside the central processing unit related to execution of the instruction processing is maintained. A device that is activated and processes the pulse period information from the pulse period measuring section to convert it into character bit information using data in a group of automatic transfer control registers provided in the memory section and writable arbitrarily by software. A barcode reading device characterized by: