CN103631725B - MCU-LCD driving method based on ARM-Linux platform and system - Google Patents

Abstract

The invention discloses MCU-LCD driving method based on ARM-Linux platform and system, the method includes: calls QT application driven LCD, and writes data to be shown to Framebuffer；After arriving the timing preset, obtain the initial address of Framebuffer data；The direction of GPIO mouth is set, and simulates MCU interface sequence, row address and the column address of MCU-LCD is set；In conjunction with the prefixed time interval of intervalometer, by GPIO mouth, the Framebuffer datacycle of acquisition is written to the GRAM video memory of MCU-LCD；MCU-LCD automatically reads the data of GRAM video memory and shows in real time.The suitability of the present invention is high, the popularization and application of beneficially MCU-LCD, thus reduces the display cost of embedded system, can be widely applied in embedded system based on ARM-Linux platform.

Description

MCU-LCD driving method based on ARM-Linux platform and system

Technical field

The present invention relates to MCU-LCD and drive field, particularly relate to a kind of MCU-LCD based on ARM-Linux platform and drive Dynamic method and system.

Background technology

Liquid Crystal Display is called for short LCD, refers to liquid crystal display, is to utilize liquid crystal material to issue at electric field action Give birth to change in location and cover a kind of flat-panel display device that the performance of penetrating light is fabricated to, use TFT type the most in a large number LCD, but for Embedded System Product, select TFT-LCD can bring the obvious increase of cost, and TFT type LCD is by chi Very little restriction is typically not easily achieved less than 3.5 inches.In this case, size is little, with low cost and controls MCU simply and easily and connects The LCD(hereinafter referred to as MCU-LCD of mouth) obtain relatively broad application.But the MCU-LCD liquid crystal display screen on market is the most all Being to use single-chip microcomputer to drive, be not particularly suited for embedded system, current type of drive can not compatible be put down based on ARM-Linux The embedded system of platform.And the ARM-Linux platform of institute of general ARM chip manufacturer mobile phone is both for TFT-LCD liquid crystal Screen is made to measure, MCU-LCD liquid crystal display screen does not do driving and supports, currently without complete, versatility is high based on The MCU-LCD driving method of ARM-Linux platform, the application cost causing MCU-LCD is higher, limits it and promotes.

Summary of the invention

In order to solve above-mentioned technical problem, it is an object of the invention to provide MCU-LCD based on ARM-Linux platform and drive Dynamic method.It is a further object of the present invention to provide MCU-LCD drive system based on ARM-Linux platform.

The technical solution adopted for the present invention to solve the technical problems is:

MCU-LCD driving method based on ARM-Linux platform, including:

S1, call QT application driven LCD, and to Framebuffer write data to be shown；

After the timing that S2, arrival are preset, obtain the initial address of Framebuffer data；

S3, the direction of GPIO mouth is set, and uses GPIO mouth die to intend MCU interface sequence, the row ground of MCU-LCD is set simultaneously Location and column address；

S4, combine the prefixed time interval of intervalometer, by GPIO mouth, the Framebuffer datacycle of acquisition is write Enter the GRAM video memory to MCU-LCD；

S5, MCU-LCD automatically read the data of GRAM video memory and show in real time.

Further, also included before described step S1:

S0, initialization timing device, and startup file system, then call QT application driven LCD, and then realize LCD Bottom layer driving.

Further, described step S5, itself particularly as follows:

The internal hardware IC of MCU-LCD reads the data of GRAM video memory automatically, and shows in real time.

Further, described prefixed time interval is 250ms.

What the present invention solved that its technical problem used another solution is that

MCU-LCD drive system based on ARM-Linux platform, including:

First module, is used for calling QT application driven LCD, and writes data to be shown to Framebuffer；

Second module, for after arriving the timing preset, obtains the initial address of Framebuffer data；

Three module, for arranging the direction of GPIO mouth, and uses GPIO mouth die to intend MCU interface sequence, arranges simultaneously The row address of MCU-LCD and column address；

4th module, for combining the prefixed time interval of intervalometer, the Framebuffer number that will be obtained by GPIO mouth According to the GRAM video memory being cyclically written to MCU-LCD；

5th module, automatically reads the data of GRAM video memory and shows in real time for MCU-LCD.

Further, also include:

Initialization module, for initialization timing device, and startup file system, then call QT application driven LCD, And then realize the bottom layer driving of LCD.

The invention has the beneficial effects as follows: the MCU-LCD driving method based on ARM-Linux platform of the present invention, driving LCD after Framebuffer write data to be shown, uses GPIO mouth die to intend MCU interface sequence, utilizes intervalometer not stop The data of framebuffer are write in the GRAM video memory of MCU-LCD by ground, thus realize the graphic picture display at MCU-LCD, In the case of retaining the driving to TFT-LCD of the ARM chip so that ARM chip can directly drive MCU-LCD, this method has There are the popularization and application of the highest general applicability, beneficially MCU-LCD, thus reduce based on ARM-Linux platform embedded The display cost of system.

Another of the present invention provides the benefit that: the MCU-LCD drive system based on ARM-Linux platform of the present invention, can Driving LCD and after the data that Framebuffer write is to be shown, using GPIO mouth die to intend MCU interface sequence, utilize timing The data of framebuffer are ceaselessly write in the GRAM video memory of MCU-LCD by device, thus realize graphic picture at MCU-LCD Display, retaining in the case of the driving to TFT-LCD of the ARM chip so that ARM chip can directly drive MCU-LCD, this System has the popularization and application of the highest general applicability, beneficially MCU-LCD, thus reduces based on ARM-Linux platform The display cost of embedded system.

Accompanying drawing explanation

The invention will be further described with embodiment below in conjunction with the accompanying drawings.

Fig. 1 is the flow chart of the MCU-LCD driving method based on ARM-Linux platform of the present invention；

ARM chip and the hardware connecting circuit frame diagram of MCU-LCD when Fig. 2 is the driving method realizing the present invention；

Fig. 3 be the present invention driving method in MCU interface write the time diagram of LCD depositor；

Fig. 4 be the present invention driving method in MCU interface read LCD depositor time diagram；

Fig. 5 is the schematic diagram showing in linux system and driving hierarchical structure；

Fig. 6 is the main driving structural representation of the Linux framebuffer device in the driving method of the present invention.

Detailed description of the invention

For the ease of following description, first provide following explanation of nouns:

ARM:Advanced RISC Machines, had both referred to the name of a company, it is also possible to refer to a class microprocessor The common name of chip, it is also possible to refer to a kind of technology；

Linux:Linux is presently the most the operating system of popular a open source code, and be currently being deployed is embedding In embedded system, the project alternatives Linux of more than 70% is as embedded OS；

ARM-Linux: linux system based on arm processor；

TFT-LCD:Thin Film Transistor-Liquid Crystal Display, TFT Liquid crystal display, is the one in active matrix type liquid crystal display (AM-LCD), uses RGB more and shows interface；

GPIO:General Purpose Input Output (universal input/output) is referred to as GPIO, or bus expands Exhibition device, function is similar to the P0-P3 of 8051, and its pin freely can be used by program control for user, and PIN can be made according to Practical Consideration For universal input (GPI) or general output (GPO) or universal input and output (GPIO), as clk, generator, chip Select etc.；

The abbreviation of GRAM:Graphics DRAM, the Chinese meaning is video memory, is also designated as frame buffer, and its effect is used to The rendering data that storage display card chip processed or will extract；

Framebuffer: framebuffer device, it is the structure that linux system provides for display device, and it will be aobvious Show that relief area is abstract, the bottom difference of masked images hardware, it is allowed to upper level applications is directly slow to display under graphic model Rush district and be written and read operation.User need not be related to particular location and the location mode of physically displayed relief area, and these are all delayed by frame Rush device drives itself to complete.For framebuffer device, if region corresponding with display point in display buffer Write color value, corresponding color can show automatically on screen；

QT application program: QT is a cross-platform C++ graphical user interface application program development framework.It both can be developed GUI formula is it can also be used to develop non-GUI formula.The graphical interface program utilizing QT to develop is called for short QT application program, QT application journey Sequence can directly directly be run in ARM-Linux system platform.

With reference to Fig. 1, the invention provides a kind of MCU-LCD driving method based on ARM-Linux platform, including:

S1, call QT application driven LCD, and to Framebuffer write data to be shown；

After the timing that S2, arrival are preset, obtain the initial address of Framebuffer data；In the present embodiment, regularly Time is preset as 1s；

S3, the direction of GPIO mouth is set, and uses GPIO mouth die to intend MCU interface sequence, the row ground of MCU-LCD is set simultaneously Location and column address；

S4, combine the prefixed time interval of intervalometer, by GPIO mouth, the Framebuffer datacycle of acquisition is write Enter the GRAM video memory to MCU-LCD；

S5, MCU-LCD automatically read the data of GRAM video memory and show in real time.

It is further used as preferred embodiment, also included before described step S1:

S0, initialization timing device, and startup file system, then call QT application driven LCD, and then realize LCD Bottom layer driving.

Be further used as preferred embodiment, described step S5, itself particularly as follows:

The internal hardware IC of MCU-LCD reads the data of GRAM video memory automatically, and shows in real time.

Being further used as preferred embodiment, described prefixed time interval is 250ms.

Present invention also offers a kind of MCU-LCD drive system based on ARM-Linux platform, including:

First module, is used for calling QT application driven LCD, and writes data to be shown to Framebuffer；

Second module, for after arriving the timing preset, obtains the initial address of Framebuffer data；

Three module, for arranging the direction of GPIO mouth, and uses GPIO mouth die to intend MCU interface sequence, arranges simultaneously The row address of MCU-LCD and column address；

4th module, for combining the prefixed time interval of intervalometer, the Framebuffer number that will be obtained by GPIO mouth According to the GRAM video memory being cyclically written to MCU-LCD；

5th module, automatically reads the data of GRAM video memory and shows in real time for MCU-LCD.

It is further used as preferred embodiment, also including:

Initialization module, for initialization timing device, and startup file system, then call QT application driven LCD, And then realize the bottom layer driving of LCD.

Below in conjunction with specific embodiment, the present invention will be further described:

MCU-LCD driving method based on ARM-Linux platform, including:

S0, initialization timing device, and startup file system, then call QT application driven LCD, and then realize LCD Bottom layer driving；

S1, call QT application driven LCD, and to Framebuffer write data to be shown；

After the timing that S2, arrival are preset, obtain the initial address of Framebuffer data；

S3, the direction of GPIO mouth is set, and uses GPIO mouth die to intend MCU interface sequence, the row ground of MCU-LCD is set simultaneously Location and column address；

S4, combine the prefixed time interval of intervalometer, by GPIO mouth, the Framebuffer datacycle of acquisition is write Enter the GRAM video memory to MCU-LCD；I.e. LCD drives and cyclically passes through GPIO mouth by acquisition with prefixed time interval Framebuffer data are written in the GRAM video memory of MCU-LCD；

The internal hardware IC of S5, MCU-LCD reads the data of GRAM video memory automatically, and shows in real time.Here, Preset Time It is spaced apart 250ms.

With reference to Fig. 2, when Fig. 2 is the driving method realizing the present invention, ARM chip and the hardware connecting circuit frame of MCU-LCD Frame figure, as in figure 2 it is shown, it is by using GPIO mouth die to intend MCU interface sequence to control MCU-that ARM chip is connected with MCU-LCD LCD.MCU-LCD has the GRAM video memory of self, therefore in the case of not power down, MCU-LCD is shown that self GRAM video memory Data.

MCU interface is mainly controlled foot by four and eight data pin that is 8 bit data interface form, and four control foot respectively Being expressed as: nCS, RS, RD and WR, wherein nCS refers to CS chip select pin, and n represents Low level effective；RS refers to data/command selection letter Number foot, RS is that low level represents write order, and RS is that high level represents and writes data；RD refers to that read/write selects signal pins, and RD is high level Representing and write depositor, RD is that low level represents read register；WR refers to write signal foot, and WR is changed into high level process by low level, In data write depositor.

MCU interface writes the sequential of LCD depositor, during as it is shown on figure 3, write LCD depositor, need to first gate LCD(nCS foot It is set to low level), putting RD foot is high level.

During write command signal, putting RS foot is low level, inputs " 00h " to data pin, then is turned by low level by putting WR foot Become high level, in " 00h " value just write depositor；Then keep RS pin level constant, input necessary life to data pin Make value " index " (this sentence index replace), be then changed into high level by low level by putting WR foot, bid value just write In depositor.

It should be noted that the data of MCU interface are made up of two bytes, but its data pin is mono-word of 8bit( Joint), it is therefore desirable to write data at twice, first write the data of most-significant byte byte, write the data of least-significant byte byte the most again. So, one data of the most complete write.

During write data signal, putting RS foot is high level, first inputs data most-significant byte byte data to data pin, then by putting WR foot is changed into high level by low level, in most-significant byte byte data just write depositor；Then keep RS pin level constant, Inputting least-significant byte byte data to data pin, be then changed into high level by low level by putting WR foot, least-significant byte byte data is just It is written with in depositor.

After writing data, then to put nCS foot be high level, protects buffer status.

Read register, to write depositor different, need first to write the order that depositor is corresponding, then could read relevant Data value.MCU interface reads the sequential of LCD depositor, as shown in Figure 4, during read register, first gates liquid crystal and (nCS foot is set to low Level), then toward the command signal that depositor write is relevant, its operation is consistent with writing register command signal.

During reading data signal, put RS foot and WR foot is high level, then by putting RD foot by three kinds of level shapes high and low, high State changes, it is possible to most-significant byte byte data is read out；Then keep RS pin and WR pin level constant, at this by putting RD foot is by three kinds of level state transition high and low, high, it is possible to least-significant byte byte data is also read out.

After running through data, then to put nCS foot be high level, protects buffer status.

Fig. 5 is the schematic diagram showing in linux system and driving hierarchical structure, as seen from Figure 5, in Linux Framebuffer display driving software can be divided into two levels: file hierarchy layer and bottom hardware key-course.

The major function of file hierarchy layer is: on the one hand achieves and jointly has various different display devices The encapsulation of certain operations, as internal memory map, the switch of file and read-write etc., and provide the file calling these operations to upper strata Layer interface, facilitates upper level applications to call；On the other hand in the key data structure of bottom hardware key-course is registered to by it In core, it is achieved mutual with kernel.Intercommunity in file hierarchy layer be accomplished that Framebuffer driver Function, its code saves as fbmem.c file, can drive for various different display devices and use.

The main task of bottom hardware key-course is to manipulate concrete hardware device (such as lcd controller) and distribution frame Buffer memory.Due to varying on hardware, so the program of this part, need according to the flush bonding processor used and The concrete condition of lcd controller is developed.This part in linux system drives code to be saved in drivers/video file In folder, such as pxafb.c, s3c2410fb.c etc.；Pxafb.c is the driver supporting PXA255 processor, and S3c2410fb.c is then to support Samsung S3C2410 processor.Driver in drivers/video file is all based on Frame structure provided in skeletonfb.c, has then been filled, so the driving side of the here present invention Method is also built upon in this framework.

Fig. 6 is the main driving structural representation of the Linux framebuffer device in the driving method of the present invention, and frame buffering sets The standby file_operations structure being supplied to user's space has the file_operations in fbmem.c to provide, and special The maintenance of the registration of framing buffer device fb_info structure, cancellation and wherein member, member function in especially fb_ops Realization then realized by corresponding xxxfb.c file, the member function in fb_ops eventually operates the depositor of LCD.In Fig. 6 Fb_mmap function and lcd_updata function are the concrete functions of the driving method realizing the present invention, and fb_mmap function is added on In fb_ops structure, Main Function initializes and starts inner core timer, goes to call lcd_updata function after waiting 1s. The effect of lcd_updata function is that timing writes the data in Framebuffer in the GRAM video memory of MCU-LCD, then GRAM will be automatically being graphically displayed in lcd screen.

As a example by the model ARM9 chip as NUC910ABN, its fb_mmap function code realizes and annotation is as follows:

int nuc900fb_mmap(struct fb_info *fbi, struct vm_area_struct *vma)

{

init_timer(&timer_mmap);// initialization timing device timer_ mmap

timer_mmap.function = lcd_updata;// timing arrives, and calls lcd_ Updata function

timer_mmap.data = 0;

timer_mmap.expires = jiffies+HZ;// regularly 1s

add_timer(&timer_mmap);// load intervalometer

return 0;

}

The code of lcd_updata function realizes and annotation is as follows:

void lcd_updata(unsigned long data)

{

int i,j;

int temp;

long *framebuffer_updata;

framebuffer_updata = reserve_virt_addr;// obtain framebuffer number According to initial address

outl(inl(NUC910_MFSEL) & ~(0xf0c0f0),NUC910_MFSEL);// side of GPIO mouth is set To

WriteCmd(0x20,0x0000);//Set horizontal address, arranges the row ground of MCU-LCD Location

WriteCmd(0x21,0x0000);//Set vertical address, arranges the column address of MCU-LCD

WriteIndex(0x00,0x22);//write data to GRAM, writes data to the GRAM of MCU-LCD Video memory

for(i=0;i<176;I++) // circulation writes data to MCU-LCD screen, and resolution is 220*176

for(j=0;j<110;j++) //220/2=110

{

temp = *(framebuffer_updata+j+110*i);

WriteData((temp>>8),temp);

WriteData((temp>>24),(temp>>16));

}

// reloading intervalometer, fixed time interval is 250ms, i.e. refreshes a GRAM every 250ms

mod_timer(&(timer_mmap),jiffies+HZ/4);

}

Being in the present embodiment as a example by NUC910ABN chip, the resolution of the MCU-LCD screen used is 220*176, but As long as be used for ARM-Linux system, be referred to the program knot that this programme design framebuffer device drives the most completely Structure, adjusts corresponding resolution and arranges and the output setting of GPIO mouth, it is possible to very easily light MCU-LCD screen.

In fb_ops structure, introduce fb_mmap function, then utilize intervalometer not stop the data of framebuffer Write GRAM realizes the graphic picture display at MCU-LCD screen, and the GPIO mouth using ARM chip all to possess connects to simulate MCU Mouth sequential, so that the driving method of the present invention has the highest general applicability.

It is above the preferably enforcement of the present invention is illustrated, but the invention is not limited to described enforcement Example, those of ordinary skill in the art it may also be made that all equivalent variations on the premise of spirit of the present invention or replacing Changing, modification or the replacement of these equivalents are all contained in the application claim limited range.

Claims (6)

1. MCU-LCD driving method based on ARM-Linux platform, it is characterised in that including:

S1, call QT application driven LCD, and to Framebuffer write data to be shown；

S2, arrive intervalometer preset timing after, obtain Framebuffer data initial address；

S3, the direction of GPIO mouth is set, and uses GPIO mouth die to intend MCU interface sequence, arrange simultaneously MCU-LCD row address and Column address；

S4, combine the prefixed time interval of intervalometer, by GPIO mouth, the Framebuffer datacycle of acquisition is written to The GRAM video memory of MCU-LCD；

S5, MCU-LCD automatically read the data of GRAM video memory and show in real time；

Described MCU-LCD represents the LCD of MCU interface.

MCU-LCD driving method based on ARM-Linux platform the most according to claim 1, it is characterised in that described Also include before step S1:

S0, initialization timing device, and startup file system, then call QT application driven LCD, and then realize the end of LCD Layer drives.

MCU-LCD driving method based on ARM-Linux platform the most according to claim 1, it is characterised in that described step Rapid S5, itself particularly as follows:

The internal hardware IC of MCU-LCD reads the data of GRAM video memory automatically, and shows in real time.

MCU-LCD driving method based on ARM-Linux platform the most according to claim 1, it is characterised in that described step Described in rapid S4, prefixed time interval is 250ms.

5. MCU-LCD drive system based on ARM-Linux platform, it is characterised in that including:

First module, is used for calling QT application driven LCD, and writes data to be shown to Framebuffer；

Second module, for, after arriving the timing preset of intervalometer, obtaining the starting point of Framebuffer data Location；

Three module, for arranging the direction of GPIO mouth, and uses GPIO mouth die to intend MCU interface sequence, arranges MCU-LCD simultaneously Row address and column address；

The Framebuffer data of acquisition, for combining the prefixed time interval of intervalometer, are followed by the 4th module by GPIO mouth It is written to the GRAM video memory of MCU-LCD ring；

5th module, automatically reads the data of GRAM video memory and shows in real time for MCU-LCD；

Described MCU-LCD represents the LCD of MCU interface.

MCU-LCD drive system based on ARM-Linux platform the most according to claim 5, it is characterised in that also wrap Include:

Initialization module, for initialization timing device, and startup file system, then call QT application driven LCD, and then Realize the bottom layer driving of LCD.