Embedded system development and labs for ARM (R. Muresan, 2005)

Embedded Systems Development and Labs; The English Edition

Figure 5-11 Power Supply and Bias Voltage Supply Circuit

2. Software Design

The Lab implementation includes 3 parts: display rectangles, characters and bit maps. 1) A Thought on Design

The basic principle of LCD display is pixel control. The pixel storage and transfer determines the effect obtained on the display. As a result, the graphics can be displayed by controlling the pixels. Storing the pixels in some order can display characters such as ASCII characters, language characters, etc.

Embest ARM development system for pixel control functions are the following: /**************************************************************************

*S3CEV40 LCD pixel display micro definition

*LCD LCD_PutPixel(x, y, c) – Send the pixel to the virtual buffer

*LCD_Active_PutPixel(x, y, c) – Send the pixel to the display buffer (directly drive LCD) /************************************************************************** #define LCD_PutPixel(x, y, c) \

(*(INT32U *)(LCD_VIRTUAL_BUFFER+ (y) * SCR_XSIZE / 2 + ( (x)) / 8 * 4)) = \ (*(INT32U *)(LCD_VIRTUAL_BUFFER+ (y) * SCR_XSIZE / 2 + ( (x)) / 8 * 4)) & \ (~(0xf0000000 >> ((( (x))%8)*4))) |((c) << (7 - ( (x))%8) * 4)

#define LCD_Active_PutPixel(x, y, c) \

(*(INT32U *)(LCD_ACTIVE_BUFFER + (y) * SCR_XSIZE / 2 + (319 - (x)) / 8 * 4)) = \ (*(INT32U *)(LCD_ACTIVE_BUFFER + (y) * SCR_XSIZE / 2 + (319 - (x)) / 8 * 4)) & \ (~(0xf0000000 >> (((319 - (x))%8)*4))) |((c) << (7 - (319 - (x))%8) * 4)

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Embedded Systems Development and Labs; The English Edition

2) Rectangle Display

The rectangle consists of two horizon lines and two vertical lines. Drawing a rectangle on the LCD is accomplished by calling the line draw function. The line draw function is alternately calling the pixel control function.

3) Character Display

Characters can be displayed using many fonts. The font size is W x H or H x W such as 8 x 8, 8 x 16, 16 x 16, 16 x 24, 24 x 24, etc. The users can make use of different character libraries for displaying different fonts. For example, the Lab system uses the 8 x 16 font to display ASCII characters. In order to display an ASCII character first we have to access the look up predefined character table. This table, used for storing characters, is called ASCII library.

The function call for the ASCII library is:

Const INIT8U g_auc_Ascii8x16[]={ //ASCII table}

The storage of ASCII table is an array that uses the value of ASCII character as its index. The relationship between the width/height and the library will be extracted during the process of the pixel-controlled drawing. The ASCII library consists of 256 ANSI ASCII characters. For detailed information, please refer to the sample programs of the Lab project.

4) Bit Map Display

Bit map display is used to convert a bitmap file into an array and store it in a data structure. Like displaying characters, displaying bit map also needs to be controlled by pixel drawing functions and transfer display data to the display buffer.

The Embest ARM development system provides the following functions that can be used for bit map display: Const INT8U ucMouseMap[] = {//Bit Map File Data}

Bit map display (please refer to the sample program) function is the following:

Void BitmapView(INT16U x, INT16U y, STRU_BITMAP Stru_Bitmap);

Bit map action (please refer to the sample program) functions are the following:

Void BitmapPush(INT16U x, INT16U y, STRU_BITMAP Stru_Bitmap);

Void BitmapPop(INT16U x, INT16U y, STRU_BITMAP Stru_Bitmap);

5.1.6 Operation Steps

(1)Prepare the Lab environment. Connect the Embest Emulator to the target board. Connect the target board UART0 to PC serial port using the serial cable that comes with the Embest development system.

(2)Run the PC Hyper Terminal (set to 115200 bits per second, 8 data bits, none parity, 1 stop bits, none flow control).

(3)Connect the Embest Emulator to the target board. Open the BMP_Display.ews project file in the BMP_Display sub directory of the Example directory. After compiling and linking, connect to the target board

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and download the program.

(4)The hyper terminal should display the followings: Please press on one key on keyboard and look at LED… Embest 44B0X evaluation board (S3CEV40)

LCD display test example (please look at LCD screen)

(5)Watch the LCD screen and you will see many rectangles, ASCII characters, mouse bitmap, etc.

(6)After understanding the details of the lab, finish the Lab exercises.

5.1.7 Sample Programs

1. Initialization Program

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Embedded Systems Development and Labs; The English Edition

#define LCD_ACTIVE_BUFFER (0xc300000)

#define LCD_VIRTUAL_BUFFER (0xc300000 + LCD_BUF_SIZE)

/***********************************************************************

*modify:

*comment:

*********************************************************************/

void Lcd_Init(void)

{

rDITHMODE=0x1223a; rDP1_2 =0x5a5a; rDP4_7 =0x366cd9b; rDP3_5 =0xda5a7; rDP2_3 =0xad7; rDP5_7 =0xfeda5b7; rDP3_4 =0xebd7; rDP4_5 =0xebfd7; rDP6_7 =0x7efdfbf;

rLCDCON1=(0)|(1<<5)|(MVAL_USED<<7)|(0x0<<8)|(0x0<<10)|(CLKVAL_GREY16<<12); rLCDCON2=(LINEVAL)|(HOZVAL<<10)|(10<<21);

M5D(LCD_ACTIVE_BUFFER>>1));

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Embedded Systems Development and Labs; The English Edition

rLCDSADDR3= (LCD_XSIZE/4) | ( ((SCR_XSIZE-LCD_XSIZE)/4)<<9 ); // enable,4B_SNGL_SCAN,WDLY=8clk,WLH=8clk,

rLCDCON1=(1)|(1<<5)|(MVAL_USED<<7)|(0x3<<8)|(0x3<<10)|(CLKVAL_GREY16<<12); rBLUELUT=0xfa40;

//Enable LCD Logic and EL back-light. rPDATE=rPDATE&0x0e;

}

2. Control Functions

1) Clear Screen Functions

/*****************************************************************

*modify:

*comment:

********************************************************************/

void Lcd_Clr(void)

{

INT32U i;

INT32U *pDisp = (INT32U *)LCD_VIRTUAL_BUFFER;

for( i = 0; i < (SCR_XSIZE*SCR_YSIZE/2/4); i++ )

{

*pDisp++ = WHITE;

}

}

/********************************************************************

*modify:

*comment:

******************************************************************/

void Lcd_Active_Clr(void)

{

INT32U i;

INT32U *pDisp = (INT32U *)LCD_ACTIVE_BUFFER;

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Embedded Systems Development and Labs; The English Edition

for( i = 0; i < (SCR_XSIZE*SCR_YSIZE/2/4); i++ )

{

*pDisp++ = WHITE;

}

}

2) Draw Line Functions

/***********************************************************************

*usX1 -- line's end point X-coordinate

*ucColor -- appointed color value

*usWidth -- line's width

*modify:

*comment:

********************************************************************/

void Lcd_Draw_HLine(INT16 usX0, INT16 usX1, INT16 usY0, INT8U ucColor, INT16U usWidth)

{

INT16 usLen;

if( usX1 < usX0 )

{

GUISWAP (usX1, usX0);

}

while( (usWidth--) > 0 )

{

usLen = usX1 - usX0 + 1; while( (usLen--) > 0 )

{

LCD_PutPixel(usX0 + usLen, usY0, ucColor);

}

usY0++;

}

}

/*********************************************************************

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*usY1 -- line's end point Y-coordinate

*ucColor -- appointed color value

*usWidth -- line's width

*modify:

*comment:

*********************************************************************/

void Lcd_Draw_VLine (INT16 usY0, INT16 usY1, INT16 usX0, INT8U ucColor, INT16U usWidth)

{

INT16 usLen;

if( usY1 < usY0 )

{

GUISWAP (usY1, usY0);

}

while( (usWidth--) > 0 )

{

usLen = usY1 - usY0 + 1; while( (usLen--) > 0 )

{

LCD_PutPixel(usX0, usY0 + usLen, ucColor);

}

usX0++;

}

}

3) Bit Map Display Function

/************************************************************************

*Stru_Bitmap -- bitmap struct

*ret: none

*modify:

*comment:

**********************************************************************/

void BitmapView (INT16U x, INT16U y, STRU_BITMAP Stru_Bitmap)

{

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INT32U i, j;

INT8U ucColor;

for (i = 0; i < Stru_Bitmap.usHeight; i++)

{

for (j = 0; j <Stru_Bitmap.usWidth; j++)

{

if ((ucColor = *(INT8U*)(Stru_Bitmap.pucStart + i * Stru_Bitmap.usWidth + j)) != TRANSPARENCY)

{

LCD_PutPixel(x + j, y + i, ucColor);

}

}

}

}

4) DMA Transfer Display Data Function

/************************************************************************

*modify:

*comment:

***********************************************************************/

void Lcd_Dma_Trans(void)

{

INT8U err;

(LCD_ACTIVE_BUFFER+(SCR_XSIZE*SCR_YSIZE/2)) rNCACHBE1=(((unsigned)(LCD_ACTIVE_BUFFER)>>12)

<<16 )|((unsigned)(LCD_VIRTUAL_BUFFER)>>12); rZDISRC0=(DW<<30)|(1<<28)|LCD_VIRTUAL_BUFFER; // inc

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5.1.8 Exercises

Refer to the sample program; display the 4 x 4 keyboard values on the LCD panel.

5.2 The 4 x 4 Keyboard Control Lab

5.2.1 Purpose

● Understand the design method of keyboard interrupt control program. ● Understand the design of the keyboard interrupt test program.

● Understand the interrupt service routine programming using the ARM core processor.

5.2.2 Lab Equipment

● Hardware: Embest S3CEV40 hardware platform, Embest Standard/Power Emulator, PC. ● Software: Embest IDE 2003, Windows 98/2000/NT/XP operation system.

5.2.3 Content of the Lab

Develop a project that accepts the keys of the keyboard pad through interrupt service routine and display the values on the 8-SEG LED.

5.2.4 Principles of the Lab

For the matrix keyboard interface, there are normally three ways of getting the keyboard values: through interrupts, through scanning, and through inversion.

●Interrupts: When a key is pressed, CPU will receive an interrupt signal. The interrupt service routine will

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read the keyboard status on the data bus through different addresses and determine which key is pressed.

●Scanning: Send low voltage to one horizontal line and high level to the other horizontal lines. If any vertical line is low, the key that sits at the intersection of the selected row and column is pressed.

●Inversion: Send low voltage to the horizontal lines and read the vertical lines. If any vertical line is low, it indicates one key is pressed on that column. Then send low voltage to the vertical lines and read the horizontal lines. If any horizontal line is low, it indicates one key is pressed on that row. The intersection of the identified row and column will give the position of the key.

5.2.5 Lab Design

1. Keyboard Hardware Circuit Design

1) 4 x 4 Keyboard

The 4 x 4 keyboard has 4 rows and 4 columns. The circuit is shown in Figure 5-12. Any pressed key will generate a pass route.

Figure 5-12 4 x 4 Keyboard Circuit

2) CPU Recognition Circuit

The keyboard recognition circuit is shown bellow:

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