JP2002041447A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer capable of stably supplying data to an engine without causing reduction of a processing speed and increment in cost in a DMA. SOLUTION: A DMA part 108 performs burst transfer of printing data stored in a RAM 105, according to a transfer request signal (DMAREQ signal) outputted from a buffer part 109. Namely, the DMA part 108 is set so as to divide the printing data into unit data for each prescribed size (32 bytes in this printer) and transfers the unit data to the buffer part 109. A shift register converts parallel data outputted from the buffer part 109 into serial data. A printing control part 107 outputs a drive signal to the engine 102.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer that transfers data to a print engine in bursts.

[0002]

2. Description of the Related Art Conventionally, a printing system in which a terminal device (a personal computer or a workstation) and a printer are connected to a network has been used. Printers installed in such systems usually include a CPU, a RAM,
It has a DMA unit, a buffer and a print engine. Of these, the RAM is used for storing print data (bitmap data) transmitted from the terminal device. The buffer is for stably supplying print data to the print engine.

[0003] In response to a request for a buffer, the DMA unit performs R
This is for sequentially sending the AM print data to the buffer. As a result, data can be transferred from the RAM to the buffer engine without using the CPU. Some printers use burst transfer for data transfer from the DMA unit to the buffer. In the burst transfer, line data (print data for one line) required for output is divided into unit data of a predetermined size (for example, 32 bytes) determined by a bus width. And for each unit data,
It is set to transfer print data at specific time intervals. This makes it possible to increase the transfer speed as compared with the normal single access method.

In burst transfer, the line data size may not be an integral multiple of the unit data size, and examples thereof are shown in FIGS. FIGS. 8A and 9A show a state in which the DMA section divides line data into unit data, and FIGS. 8B and 9B show a state of recording in the buffer. Conventionally, as shown in FIG. 8, a burst transfer is performed by adding NULL data (data corresponding to white) to a surplus portion where unit data cannot be formed. Further, as shown in FIG. 9, a method of transferring only a surplus portion of line data by a single access method has been adopted.

[0005]

However, in the method shown in FIG. 8, the DM data is added in order to add NULL data.
The software processing of A needs to be complicated. For this reason, D
The processing speed (performance) in MA has been reduced. There is also a problem that the memory capacity (the capacity of the RAM and the buffer memory) is excessively consumed by the NULL data.

Further, in the method shown in FIG. 9, a large amount of time is consumed for transferring the surplus part due to the low speed of the single access method. For this reason, when the speed of data supply from the buffer to the engine is increased, the data in the buffer runs out, and there is a problem that data cannot be supplied to the engine.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and provides a stable supply of data to an engine without causing a decrease in processing speed and an increase in cost in DMA. The purpose is to provide a printer that can.

[0008]

According to the present invention, there is provided a memory for storing print data, an engine unit for printing on paper based on the print data, and a print data stored in the memory for the engine unit. The printer includes a buffer for transferring, and a DMA unit for generating unit data by dividing print data stored in the memory for each predetermined size and performing burst transfer to the buffer. The DMA
The unit divides the print data into unit data sequentially from the top,
If the valid data of the last remaining print data is smaller than the unit data, the portion less than the size of the unit data is filled with unspecified data and mixed data consisting of valid data and unspecified data is generated. , The buffer
It is characterized in that valid data is extracted from the hybrid data and supplied to the engine.

In the printer according to the present invention, the DMA unit acquires hybrid data information for specifying hybrid data from the size of the print data and the unit data, and transmits the hybrid data information to the buffer. The size of the valid data included in the hybrid data is specified from the size of the data, and the valid data is extracted from the hybrid data based on the hybrid data information and the valid data size.

In the printer according to the present invention, the buffer includes an N-stage buffer memory for storing unit data one by one, and sequentially moves data in the N-stage buffer memory to supply the data to the engine. A control unit for setting a specific flag in the buffer memory holding the mixed data based on the mixed data information, and specifying the size of the valid data included in the mixed data from the size of the print data and the unit data. When the flag is set in the buffer memory at the last stage, a valid data extracting unit for extracting valid data from the unit data in the memory is provided.

The printer according to the present invention is characterized in that the control unit moves the flag together with the mixed data in the buffer memory of N stages.

In the printer according to the present invention, the control unit may move the unit data after confirming that the destination buffer memory is empty when moving the unit data in the N-stage buffer memory. It is characterized by the following.

In the printer according to the present invention, when the buffer memory at the front stage becomes empty,
It is characterized by requesting the transfer of new unit data to the unit A.

The printer according to the present invention is characterized in that the DMA unit continuously generates unit data from the beginning to the end of the print data, and transfers the unit data to the buffer in the order of creation. .

The printer according to the present invention is characterized in that the DMA unit continuously generates unit data from the beginning to the end of the print data, and transfers the unit data to the buffer in the reverse order of the creation order. Is what you do.

In the present invention, in order to transfer the print data in the memory to the buffer unit, burst transfer of the print data to the buffer unit for each unit data is used. Then, the print data is divided into unit data sizes, and even when the effective data finally decreases, unit data (mixed data) is created in combination with other data (unspecified data) and burst transfer is performed. It has become. As a result, the burst transfer can be always performed, and the transfer speed can always be kept high. In addition, in order to create hybrid data in combination with valid data, NU
Instead of LL data, unspecified data in a memory (for example, other data stored adjacent to untransferred print data) is used. Accordingly, since there is no need to perform complicated processing such as adding NULL data, burst transfer can be performed without reducing the processing capacity of the DMA. Further, since there is no need to prepare a memory for NULL data, it is possible to suppress the amount of memory consumption.

[0017]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the printer according to the present invention. This printer is connected to a network together with a terminal device (host PC; notebook computer or workstation) 111,
It has a function of printing print data transmitted from each terminal device.

As shown in FIG. 1, the printer has a printer controller 101 and an engine 102. The engine 102 forms a toner image on a predetermined sheet (recording paper) based on the input print data. Also, the printer controller 101
Is the accumulation of print data transmitted from the terminal device 111,
The print data is supplied to the engine 102.

As shown in FIG. 1, the printer controller 101 includes a CPU 103, a ROM 104, a RAM 10
5, host I / F 106, print control unit 107, DM
A section 108, buffer section 109, shift register 110
It has. The ROM 104 is a memory for storing a program used by the CPU 103. The host I / F 106 is an interface for receiving transmission of print data from the terminal device 111. RA
M105 is a memory for storing the transmitted print data. The buffer unit 109 includes a buffer memory for storing print data (parallel data in a bitmap format). The detailed configuration of the buffer unit 109 will be described later.

The DMA unit 108 responds to a transfer request signal (DMAREQ signal) from the buffer unit 109 by
5 for burst transfer of the print data stored in the storage unit 5. That is, the DMA unit 108 divides the print data into unit data for each predetermined size (32 bytes in this printer). Then, the setting is made so that the unit data is transferred to the buffer unit 109. The method of generating the unit data in the DMA unit 108 will be described later.

The shift register 110 includes a buffer unit 10
9 is for converting the parallel data output from 9 into serial data. The print control unit 107 outputs a drive signal to the engine 102. In addition,
The engine 102 is set to output a synchronization signal according to the drive signal. Then, the upper print control unit 107 issues a shift request to the shift register 110 in accordance with the synchronization signal and the synchronization clock, converts the parallel data into serial data, transmits the serial data to the engine 102, and transmits the parallel data from the buffer unit 109. A LOAD signal to be transmitted to the shift register 110 is transmitted to the buffer unit 10
9 is provided. That is, the LOAD signal is a data load signal for the shift register 110, and stores data in synchronization with this signal. Furthermore, SI
The FTEN signal is an enable signal for the shift register 110, and shifts the parallel data while the signal is valid.

The CPU 103 is connected to each of the devices 104 to 110 via the CPU BUS.
4 to 110, a function of appropriately transmitting print data transmitted from the outside to the engine 102.

Next, a method of processing the unit data in the DMA unit 108 will be described. RAM1 of this printer
The print data stored in 05 (see FIG. 1) is a unit of line data of a predetermined number of bytes. And
The DMA unit 108 is set to divide this line data into unit data of 32 bytes in order to perform burst transfer.

FIG. 2A shows a state in which the DMA section divides line data into unit data, and FIG. 2B shows a state of recording in a buffer. As shown in FIG. 2, when a plurality of 120-byte line data are collected to form print data, the DMA unit 108 first creates three unit data (32 bytes) from the first line data.
Since 3 × 32 = 96 bytes, the unit data (32 bytes) is formed by combining the remaining 24 bytes of data in the first line data with the first 8 bytes in the second line data. Then, three unit data are taken from the remaining 112 bytes of data in the second line data, and the remaining 16 bytes are combined with the first 16 (112−3 × 32) bytes of the third line data to form the unit data. I do.

As described above, when the surplus part of the line data (120 bytes) is smaller than 32 bytes, the DMA unit 108 combines the surplus part with another part of the line data to create unit data. Has become. If the surplus portion of the print data becomes smaller than 32 bytes in the last line data (L line in FIG. 2), the DMA unit 108 stores the surplus portion in the RAM 1
The unit data is set so as to be combined with unspecified data (undefined data) stored adjacent to the print data in the unit 05.

The indefinite data is used for burst transfer of the print data, and is included only in the unit data (mixed data) created last. As the indefinite data, for example, other data stored adjacent to the surplus portion of the print data can be used. Here, the print data portion (portion that is not indefinite data) included in the mixed data is referred to as valid data.

The DMA unit 108 is set to transfer the unit data created as described above to the buffer unit 109 in the order of creation. Therefore, the unit data transferred last is mixed data. Thus, BITMA
The bit-mapped print data is sent to the buffer unit 109 as a P DATA signal. The DMA unit 10
Reference numeral 8 denotes unit data to be transferred last with respect to the mixed data to be transferred last. (Last-
flag). Similarly, the DMA unit 108 adds information (first-flag) indicating the unit data to be transferred first to the unit data to be transferred first. Further, the DMA unit 108 is set so as to transmit information (lower bit information) indicating the lower 5 bits in the print data (valid data) to the buffer unit 109. The BYTESIFT DATA signal is lower bit information sent from the DMA unit 108 to the buffer unit 109.

Next, a detailed configuration of the buffer unit 109 will be described. As shown in FIG.
Are a multi-stage buffer 301, a selector 302, a buffer control unit 303, a valid byte buffer 405, and a determination unit 406.
It is composed of The multi-stage buffer 301 includes N stages of buffer memories 403_0 to 403_N connected in series.
It consists of Note that each buffer memory 403_
In 0 to 403_N, 32-byte unit data is stored one by one. Further, as shown in FIG. 3, each of the buffer memories 403_0 to 403_N has the last-flag and the first-flag described above.
Flag storage units 401_0 to 401_4 for setting
01_N and last flag storage units 402_0 to 402_402
_N are provided.

Then, the last flag storage section 402 of the buffer memory storing the finally transferred hybrid data is stored.
_0 to 402_N have the last-flag, and the first flag storage units 401_0 to 401_4 of the buffer memory storing the unit data transferred first.
The first_flag is set to 01_N.

The selector 302 selects 1-byte data to be transferred from the last buffer memory 403_N to the shift register 110 (see FIG. 1) from parallel data. That is, the selector 302 stores 32 bytes (64 bits ×
The unit data (parallel data) of 4) is received, and 8-bit parallel data is selected from the unit data.
Under the control of the print control unit 107 (see FIG. 1), the setting is made so that the parallel data is output to the shift register 110.

The buffer control unit 303 includes the engine 102
The serial data stored in the selector 302 is transmitted to the engine 102 according to the synchronization signal output from the. Further, the buffer control unit 303
In 1, the unit data in each of the buffer memories 403_0 to 403_N is sequentially moved to the subsequent buffer memory. Here, the LATCH_0 to LAT_N signals are latch signals of the respective buffer memories 403_0 to 403_N. Further, the buffer control unit 303 has a function of outputting a DMAREQ signal (a signal requesting data) to the DMA unit 108 and requesting the next unit data when the buffer memory 403_0 of the multi-stage buffer 301 becomes empty. Have.

The buffer control unit 303 has a last-fl
When unit data to which ag or first-flag is added is transferred, the last-f
The flag and the first-flag are set in the first flag storage unit 401_0 and the last flag storage unit 402_0. Also, the buffer control unit 303
The symbol-indicates that the last-flag or the first-flag is similarly moved in the last flag storage units 402_0 to 402_N or the first flag storage units 401_0 to 402_N in accordance with the movement of the unit data.

The valid byte buffer 405 shown in FIG.
This is a buffer for storing lower-order bit information sent from the DMA unit 108. The BYTESIFT DATA signal is lower-order bit information sent from the DMA unit 108 to the valid byte buffer 405. The determination unit 406 determines the size (the number of bytes) of valid data in the mixed data based on the lower bit information when the mixed data is stored in the buffer memory 403_N. That is, the size of the effective data and the lower bit information have a certain correlation according to the size of the unit data. Then, the determination unit 406 sends select data to the selector 302 so as to extract valid data from the correlation. Among these, the lower bit is the DMA unit 1
08 corresponds to the lower bits of the number to be transferred.

Here, extraction of valid data by the selector 302 will be described. As shown in FIG.
Four 38-byte line data are collected at addresses 0x1000 to 0x1099 in the RAM 105 to form 152-byte print data. As shown in FIG. 4B, the unit data to be burst-transferred fifth is 32 units.
− (152−32 × 4) = mixed data including undefined data of 8 bytes.

In this case, the valid byte buffer 40
5 stores the lower bits of the number of transfer bytes of the DMA input from the DMA unit 108. In this example, D
The number of MA transfer bytes is 152 bytes. If the unit data is 32 bytes, the lower 5 bits of the value “152” are stored and “24” is stored. That is, the remainder after dividing "152" by the unit data "32" is stored as the lower bit. The determination unit 406 obtains the effective data size (24 bytes) based on the lower bit information stored in the effective byte buffer 405, and determines the effective data size (24 bytes).
To communicate.

The judging unit 406 includes a buffer memory 403_
N is stored in the last flag storage unit 402.
When the last-flag is set to _N, it is determined that the transmitted effective data size is 24 bytes.
Then, a select signal (SELDAT signal) is sent to the selector 302 so as to extract the first 24 bytes of data from the input mixed data. Selector 302
Then, 24 bytes of valid data are extracted for each byte from the select signal and output to the shift register 110. S
The IFTDAT signal is a data signal to the shift register 110. In the shift register 110, 7 bits (0
The parallel data is shifted so that serial data is output from the (bit) -th bit. At this time, from the data format, the shift is performed so that the serial data is output from the 7th bit in the normal printing and from the 0th bit in the 180 ° rotation printing.

In the above description, as shown in FIG.
The generation of unit data by the MA unit 108 is continuously performed from the head to the end of the print data. The DMA unit 108 is set so as to transfer the unit data created as described above to the buffer unit 109 in the order of creation. Therefore, mixed data including indefinite data is transferred to the buffer unit 109 last. According to this method, since the generation and transfer of the unit data can be performed at the same time, the speed of the generation and transfer processing of the unit data can be improved. However, when the print data is to be rotated by 180 degrees and printed, it is necessary to transmit the print data from the end portion. In this case, the DMA unit 1
08 is set so that each unit data is transferred to the buffer unit 109 in the reverse order of the creation order. Therefore, mixed data including indefinite data is transferred to the buffer unit 109 first.

In this case, as shown in FIG.
5, when four 38-byte line data are collected at addresses 0 × 1000 to 0 × 1099 to form 152-byte print data, the first burst-transferred unit data is 8-byte indefinite data Is mixed data.

In this case, the valid byte buffer 405
The effective data size (24 bytes) is obtained in the same manner as in the example shown in FIG. Judgment unit 406
Indicates that mixed data is stored in the buffer memory 403N,
First-flat is stored in the first flag storage unit 401N.
When g stands, it is determined that the effective data size is 24 bytes. Then, a select signal is sent to the selector 302 so as to extract the latter 24 bytes of data from the input mixed data. The selector 302 extracts the latter 24 bytes of the valid data from this select signal for each byte, and outputs it to the shift register 110.

FIG. 6 is a flowchart showing the process of extracting valid data in the judgment section 406 described above. As shown in this figure, when the print data is not rotated, the determination unit 406 determines the size (A) of the effective data and then
When mixed data to which the “ast-flag” is added is input, the selector 3 transmits data from the first byte data of the mixed data to the shift register 110.
02 selects mixed data for each byte (S0 to S
5). Then, after outputting A bytes of data, the process is terminated (S4 to S8).

The determination unit 406 determines that the print data is 18
In the case of rotation by 0 degrees, after the size (A) of valid data is grasped, when hybrid data to which First-flag is added is input, (unit data size-A) -th 1-byte data in the hybrid data Then, the selector 302 selects mixed data for each byte so as to transmit the mixed data to the shift register 110 (S0, S9 to S13). Then, after outputting A bytes of data, the process is terminated (S12 to S15, S8).

BUF [BYTE_SIFTCN]
T] are BUF [0], BUF [24], B described in the 32-byte buffer diagrams shown in FIGS.
UF [31] and the like, which indicates the positional relationship of each byte in the 32-byte buffer. That is, SIFTC
NT_BUF [BYTE_SIFTCNT] is BY
1 byte at the position indicated by TE_SIFTCNT is set to SI
This indicates that FTDAT is selected.

The valid bytes [4: 0] described in S1 and S9 in the figure indicate the lower 5 bits of the DMA transfer count. Here, EMPTY_N shown in S8 is a signal indicating that the data in the buffer memory 403_N has moved to the shift register 110, and the determination unit 40
6 to the buffer control unit 303.

Here, the process of moving and storing unit data by the buffer control unit 303 will be described with reference to the flowchart of FIG. As shown in this figure, the buffer memories 403_0 to 403_N of the multi-stage buffer 301
In response to the reset signal from the CPU 103, the setting is made so that all of them become empty (S21). After that, the buffer control unit 303 updates the buffer memories 403_0 to 403_N
It is checked from the downstream side (from the buffer memory 403_N side) whether or not data is stored in the memory.

After confirming that the buffer memory 403_0 is empty (S27), the buffer controller 303
Outputs a DMAREQ signal to the DMA unit 108 (S29). Then, the buffer control unit 303 stores the transferred unit data in the buffer memory 403_0 and stops the DMAREQ signal (S30, S30).
31). Then, after confirming that the buffer memory 403_1 is empty, the buffer control unit 303 transmits the data in the buffer memory 403_0 to the buffer memory 403 (S27, S28). And again DMAREQ
A signal is output and the unit data is stored in the buffer memory 403_0 (S29, S30). As described above, after confirming that the downstream (later) buffer memory is empty, the buffer controller 303 sequentially moves the unit data from the upstream (previous) buffer memory. . Then, after the entire unit data is moved to empty the buffer memory 403_0, a DMAREQ signal is output to store the unit data in the buffer memory 403_0.

After storing the unit data in the buffer memory 403_N, the buffer control unit 303 stops moving the unit data until the above-mentioned EMPTY_N signal is output from the determination unit 406 (S22). And
Data movement is resumed in response to the output of the EMPTY_N signal.

As described above, in the present printer, when the DMA unit 108 generates unit data from print data, if the valid data in the print data becomes smaller than the unit data, the DMA unit 108 It is set to generate hybrid data composed of data. Then, the selector 302 in the buffer unit 109 extracts valid data from the mixed data, and
Is set to be supplied to the engine 102 via the. That is, in the present printer, even when the remaining print data becomes small, unit data (mixed data) is created in combination with other undefined data, and burst transfer is performed. This makes it possible to keep the transfer speed high at all times.

Further, in order to create hybrid data in combination with valid data, unspecified data in a memory is used instead of NULL data as in the related art. Thus, since there is no need to perform complicated processing such as adding NULL data, burst transfer can be performed without reducing the processing capacity of the DMA unit 108. Further, since it is not necessary to prepare a memory for NULL data, the amount of consumption in the RAM 105 can be suppressed.

In this printer, the judgment unit 406
However, the effective data size included in the mixed data is estimated from the lower bit information in the print data. Therefore, the setting is made so as to avoid performing a special operation for calculating the effective data size. The buffer control unit 3 in the buffer unit 109
Reference numeral 03 indicates that when the unit data is moved in the buffer memories 403_0 to 403_N, the unit data is moved after confirming that the destination buffer memory is empty. As a result, it is possible to prevent new data from being written in the buffer memory in which data remains, so that data loss can be avoided. Note that "the buffer memory is empty" means that the data in the buffer memory has been moved to the buffer memory at the subsequent stage, and does not necessarily indicate that the data has been erased.

Further, when the buffer memory 403_0 at the first stage becomes empty, the buffer control unit 303
The setting is made so as to request the A unit 108 to transfer new unit data. This makes it possible to perform a transfer request without waste without using complicated timing control.

The printer of the present invention can set a memory for storing bitmap data and the number of transfer bytes, and can perform burst transfer with a width of several bytes. It has a DMA, an N-stage buffer for writing data from the memory by the DMA transfer, and a printer control unit for transferring data from the buffer to the shift register and outputting serial print data. And a flag indicating the last burst transfer, a buffer indicating the number of valid bytes in the burst width,
It is characterized by having a judging unit which judges from the flag and the buffer and selects data to be transferred to the shift register from the buffer. According to this configuration, when the effective byte width and the burst width of the memory are different, it is possible to output the print data at a high speed without stopping the DMA burst transfer or creating the bitmap data according to the burst transfer width. Make it possible.

Further, the printer of the present invention is characterized in that the flag indicating the last burst transfer has a control unit for moving the flag in the same manner as the N-stage buffer moves to the next-stage buffer. . According to this, it is possible to control which buffer of the N-stage buffer is the last burst transfer in the same manner as the control unit of the N-stage buffer without special control.

In the printer of the present invention, the buffer indicating the number of valid bytes uses data of several lower bits of the number of transfer bytes set by DMA. According to this, the number of valid bytes can be determined without special calculation in the DMA.

In the printer of the present invention, the first
In the configuration of the printing apparatus, the movement of the N-stage buffer to the next stage includes a buffer control unit that determines whether the buffer is empty, and performs a transfer request to the previous stage and a write to the next stage. I have. According to this, it is possible to prevent data loss by confirming that there is data at the previous stage and that the buffer at the next stage is empty.

Further, the printer of the present invention is characterized in that a request signal to the DMA is generated when the first buffer is empty. As a result, a transfer request can be made without waste by only managing the state of the buffer without performing complicated timing and timing control.

Further, in the printer according to the present invention, the buffer indicating the number of valid bytes has a determination unit which is used only when a flag indicating the last burst transfer is moved to the last stage. According to this,
A buffer indicating the number of valid bytes is not required for N stages, and it is possible to make a determination with only one stage.

The printer of the present invention can set a memory for storing bitmap data and the number of transfer bytes.
A DMA capable of burst transfer with a width of several bytes, an N-stage buffer for writing data from the memory by the DMA transfer, and a bit map created when image data is rotated by 180 degrees for double-sided printing or the like. The printer control unit transfers data from the buffer to the shift register by DMA address decrement and outputs serial print data. A flag indicating a burst transfer, a buffer indicating the number of valid bytes within the burst width, and a determination unit that determines from the flag and the buffer and selects data to be transferred to the shift register from the buffer. Features. According to this configuration,
If the effective byte width of the memory is different from the burst width, the DMA burst transfer is stopped or the bitmap data is created in accordance with the burst transfer darkness even when the image data is rotated by 180 degrees for double-sided printing or the like. This makes it possible to output print data at a high speed without any problem.

[0058]

According to the present invention, in order to transfer the print data in the memory to the buffer unit, so-called burst transfer in which the print data is transferred to the buffer unit for each unit data is used. In particular, in the above configuration, even when the effective data becomes small, unit data (hybrid data) is created in combination with other data, and burst transfer is performed. This makes it possible to keep the transfer speed high at all times. Further, in order to create hybrid data in combination with valid data, unlike in the related art, instead of NULL data, unspecified data (for example, data stored adjacent to untransferred print data) Data).
Accordingly, since there is no need to perform complicated processing such as adding NULL data, burst transfer can be performed without reducing the processing capacity of the DMA. Further, since there is no need to prepare a memory for NULL data, it is possible to suppress the amount of memory consumption.

Also, according to the present invention, the buffer is
Since the hybrid data information is transmitted from the section A, it is necessary to determine in what order the unit data generated in the print data will be the hybrid data and the size of the effective data in the hybrid data. Can be. The size of the valid data is obtained, for example, by dividing the size of the print data by the size of the unit data. In other words, the quotient in the division indicates the generation order of the mixed data, and the remainder indicates the effective data size. Therefore, by performing such a simple calculation in the buffer, it becomes possible to easily specify the mixed data and extract the valid data.

Further, according to the present invention, when a flag is set in the buffer memory of the last stage, the buffer memory of the N stage is provided because it has a valid data extracting unit for extracting valid data from the unit data in this memory. There is no need to move information indicating the effective data size together with the mixed data in the memory. Thereby, the complexity of the buffer can be suppressed.

According to the present invention, the flag is moved together with the mixed data in the buffer memory of N stages, so that the buffer memory holding the mixed data can be easily specified.

Further, according to the present invention, when the unit data is moved in the N-stage buffer memory, the unit data is moved after confirming that the destination buffer memory is empty. New data can be prevented from being written to the buffer memory, and data loss can be avoided.

Further, according to the present invention, the transfer of unit data is requested according to the state of the buffer memory. This makes it possible to make a transfer request without waste without performing complicated timing control. Here, complicated timing control means that, in the engine section, data transfer is also performed at a fixed cycle because mechanical operation is constant.
In the printer controller, data cannot be transferred in a fixed cycle under the bus conditions of CPU and DMA. For that reason,
It indicates that it is necessary to manage data transfer timing in the engine and perform DMA control.

Further, according to the present invention, since the created unit data is sequentially transferred to the buffer, the generation and transfer of the unit data can be performed simultaneously, and the speed of the generation and transfer processing of the unit data can be improved.

Further, according to the present invention, since the unit data is transferred to the buffer in the reverse order of the creation order, the print data can be printed while being rotated by 180 degrees.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a printer according to the invention.

FIG. 2 is an explanatory diagram showing a state in which a DMA unit divides line data into unit data and an arrangement of data.

FIG. 3 is a block diagram illustrating a buffer unit.

FIG. 4 is an explanatory diagram showing unit data that is sequentially burst-transferred by sequentially dividing print data of 152 bytes.

FIG. 5 is an explanatory diagram showing unit data subjected to inversion burst transfer by sequentially dividing print data of 152 bytes.

FIG. 6 is a flowchart illustrating a process of extracting valid data in a determination unit.

FIG. 7 is a flowchart illustrating unit data movement / storage processing by a buffer control unit;

FIG. 8 is an explanatory diagram showing a state in which a DMA unit of a conventional printer divides line data into unit data and an arrangement of data.

FIG. 9 is an explanatory diagram showing another state in which a DMA unit of a conventional printer divides line data into unit data and another arrangement of data.

[Explanation of symbols]

101: Printer controller 102: Printer engine 103: CPU 104: ROM 105: RAM 106: Host I / F 107: Print control unit 108: DMA 109: Buffer unit 110: Shift register CPUBUS: System bus from CPU FIRSTFLAG: To DMA LASTFLAG: Signal indicating the last transfer to DMA BYTESIFTDATA: Data indicating the number of valid bytes in burst transfer BITMAPDATA: Bit-mapped print data DMAREQ: DMA request signal LOAD: Transfer to shift register Signal SIFTEN: shift register enable signal

Claims (8)

[Claims] A memory for storing print data; an engine unit for printing on paper based on the print data; a buffer for transferring print data stored in the memory to the engine unit; Generates unit data by dividing the stored print data for each predetermined size,
A DMA unit for performing a burst transfer to the buffer, wherein the DMA unit sequentially divides the print data into unit data from the beginning, and when the valid data of the last remaining print data becomes smaller than the unit data. Is filled with unspecified data in a portion less than the size of the unit data, generates mixed data composed of valid data and unspecified data, the buffer extracts valid data from the mixed data,
A printer, wherein the printer is supplied to the engine. 2. The DMA unit obtains mixed data information for specifying mixed data from the size of print data and unit data, and transmits the mixed data information to the buffer. 2. The printer according to claim 1, wherein a size of valid data included in the hybrid data is specified, and valid data is extracted from the hybrid data based on the hybrid data information and the valid data size. 3. The buffer includes: an N-stage buffer memory for storing unit data one by one; and sequentially moving data in the N-stage buffer memory to supply the data to the engine. The control unit sets a specific flag in the buffer memory holding the hybrid data based on the size of the print data and the unit data, and specifies the size of the effective data included in the hybrid data, and the buffer at the last stage. 3. The printer according to claim 2, further comprising a valid data extracting unit that extracts valid data from the unit data in the memory when the flag is set in the memory. 4. The printer according to claim 3, wherein the control unit moves the flag together with the mixed data in an N-stage buffer memory. 5. The method according to claim 1, wherein the control unit moves the unit data after confirming that the destination buffer memory is empty when moving the unit data in the N-stage buffer memory. Item 7. The printer according to Item 3. 6. The printer according to claim 3, wherein the control unit requests the DMA unit to transfer new unit data when the buffer memory at the first stage becomes empty. 7. The printer according to claim 1, wherein the DMA unit continuously generates the unit data from the head to the end of the print data, and transfers the generated data to the buffer in the order of generation. 8. The method according to claim 1, wherein the DMA unit continuously generates the unit data from the beginning to the end of the print data, and transfers the unit data to the buffer in the reverse order of the creation order. The printer as described.