stk504_lcd.c File Reference

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Detailed Description

Functions used to control the STK504 LCD.

Application note:

AVR063: LCD Driver for the STK504

Documentation:

For comprehensive code documentation, supported compilers, compiler settings and supported devices see readme.html

Author:

Atmel Corporation: http://www.atmel.com
Support email: avr@atmel.com

Name

RELEASE_1_1

Revision

1.3

RCSfile

stk504_lcd.c,v

Date

2006/02/16 18:04:59

Definition in file stk504_lcd.c.

#include "stk504_lcd.h"
#include "defines.h"
#include <iom3290.h>
#include <inavr.h>

Include dependency graph for stk504_lcd.c:

Go to the source code of this file.

Functions
void	LCD_AllSegments (unsigned char input)
	Fills the Whole display buffer with one's or zero's.
void	LCD_BarSeg (unsigned char value)
	Write a hex value to the 8 bar segments on the display.
void	LCD_init (void)
	Initializes the ATmega3290 to use the STK504 Display.
void	LCD_PutChar (unsigned char c, unsigned char digit)
	Diplays a character on the 14-segment digits.
void	LCD_PutDigit (unsigned char c, unsigned char digit)
	Write a hex value to one of the 7-segment digits on the display Digit 0 has a special case as it can only display '-' and '1'. Digit[1..4] can display [0..9][A..F] See LCD_digit_table[] for some special symbols that can also be displayed.
void	LCD_SetSeg (unsigned char symbol, unsigned char input)
	Turns ON or OFF a segment in the LCD display buffer.
void	LCD_Update (void)
	Moves display buffer content to LCDDR[0..19]. Allows forced update to the phyhsical LCDDR registers, instead of setting updateRequired and waiting for the interrupt to update the LCD registers.
__interrupt void	LCD_vect_interrupt (void)
	LCD Interrupt Routine to latch the LCD_displayData and Set LCD_status.updateComplete.
Variables
__flash unsigned int	LCD_character_table []
	Look-up tables for 14-segment characters.
__flash unsigned char	LCD_digit_table []
	Look-up tables for 7-segment characters.
unsigned char	LCD_displayData [LCD_REGISTER_COUNT]
	LCD display buffer (for double buffering).
_LCD_status	LCD_status = {0x01}
	LCD_status = {0, 0, 0, 0, 0, 0, FALSE, TRUE};.
unsigned char	LCD_timer = LCD_TIMER_SEED

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Function Documentation

void LCD_AllSegments (  unsigned char  input  )

Fills the Whole display buffer with one's or zero's. Parameters: input  Used as boolean. 0x00 == OFF, [0x01 .. 0xFF] == ON Definition at line 282 of file stk504_lcd.c. References LCD_displayData. Referenced by LCD_init(). { unsigned char i; unsigned char *ptr; if( input ) // If input == TRUE input = 0xFF; // set segments to 0xFF. // (else set segments to 0x00) ptr = LCD_displayData; i = 20; do // Fill the display buffer. { *ptr++ = input; // Set/clear the bits in all LCD registers. } while ( --i ); }

void LCD_BarSeg (  unsigned char  value  )

Write a hex value to the 8 bar segments on the display. Parameters: value  Hex value to be displayed in the LcdBar segments. Valid range is [0 .. 0xFF] Definition at line 343 of file stk504_lcd.c. References LCD_displayData. Referenced by main(). { unsigned char mask, i, n, m; unsigned char *ptr; mask = 0x80; ptr = LCD_displayData + 18; // Point to the first relevant LCDDR; i = {0,0,1,1,2,2} for(n=0; n<4 ; n++) { i=0; for(m=0; m<2; m++) { i |= ( value & mask ); i >>= 1; value <<= 1; // Shift next bits into position } // At this point high variable i high nibble contain | 0 | sn | sn+1 | 0 | starting with LSBs *ptr = i | (*ptr & 0x9F); // 0x9F is mask to erase old bit values in ptr -= 5; // next segment register. } }

void LCD_init (  void   )

Initializes the ATmega3290 to use the STK504 Display. Definition at line 399 of file stk504_lcd.c. References FALSE, LCD_AllSegments(), LCD_CONTRAST_LEVEL, and LCD_INITIAL_CONTRAST. Referenced by main(). { LCD_AllSegments( FALSE ); // Clear segment buffer. PRR &= ~(1<<PRLCD); // Make sure LCD isn't disabled in power reduction register LCDCRA = (1<<LCDEN); // Enable LCD. LCD_CONTRAST_LEVEL(LCD_INITIAL_CONTRAST); //Set the LCD contrast level. // Select asynchronous clock source, enable all COM pins and enable all segment pins. LCDCRB = (1<<LCDCS) | (1<<LCDMUX1) | (1<<LCDMUX0) | (1<<LCDPM3)| (1<<LCDPM2) | (1<<LCDPM1)| (1<<LCDPM0); LCDFRR = (1<<LCDPS0); // Set LCD prescaler to CLK(lcd)/64 = 64Hz. LCDCRA |= (1<<LCDIE); //Enable LCD_Start_frame interrupt. } Here is the call graph for this function:

void LCD_PutChar (  unsigned char  c, unsigned char  digit )

Diplays a character on the 14-segment digits. Parameters: c  Character to be displayed. digit  Which digit to be write. Valid range [1..7]. Definition at line 134 of file stk504_lcd.c. References LCD_character_table, and LCD_displayData. Referenced by main(). { unsigned int seg, segMask; unsigned char i; unsigned char mask, nibble, nibbleMask; unsigned char *ptr; if ( digit == 0 || digit >=8) { return; //digit is out og range. } //Lookup character table for segment data. if ( (c >= '*') && (c <= 'z') ) { if ( c >= 'a' ) c &= ~0x20; // c is in character_table. Convert to upper if necessarry. c -= '*'; if ( c > 0x35 ) { return; // c points outside array. } else { seg = LCD_character_table[c]; } } else { return; //ASCII code out of range. } // Adjust mask according to digit segMask = 0x4008; // masking out two bits not part of the segment. i = digit-1; //i used as pointer offset. if ( i >= 8 ) //Test if LCD digit is out of range. return; i >>= 1; ptr = LCD_displayData + i; // Point to the first relevant LCDDR; i = {0,0,1,1,2,2} i = 4; //i used as loop counter. do { nibble = seg & 0x000F; nibbleMask = segMask & 0x000F; seg >>= 4; segMask >>= 4; if ( digit & 0x01 ) { mask = 0xF0 | nibbleMask; } else { nibble <<= 4; mask = 0x0F | ( nibbleMask <<4 ); } *ptr = (*ptr & mask) | nibble; //Write new bit values. ptr += 5; } while ( --i ); }

void LCD_PutDigit (  unsigned char  c, unsigned char  digit )

Write a hex value to one of the 7-segment digits on the display Digit 0 has a special case as it can only display '-' and '1'. Digit[1..4] can display [0..9][A..F] See LCD_digit_table[] for some special symbols that can also be displayed. Parameters: c  Character to be displayed on the 7-segment digit. Valid range is ['*' .. 'F'] digit  Which digit to use. Valid Range [0 .. 4] Definition at line 207 of file stk504_lcd.c. References BC8, G8, LCD_digit_table, LCD_displayData, and LCD_SetSeg(). { unsigned char i, j, seg; unsigned char mask, lastnibblemask, lookupdata; unsigned char *ptr; //special case for digit = 0 if (digit == 0) { LCD_SetSeg( G8, 0 ); LCD_SetSeg( BC8, 0 ); if ( c == '-' ) { LCD_SetSeg( G8, 1 ); } else { if ( c == '1' ) { LCD_SetSeg ( BC8, 1 ); } } return; } if ( (c >= '*') && (c <= 'F') && (digit <= 4)) { c -= '*'; lookupdata = LCD_digit_table[c]; // c is in character_table. } else { return; // ASCII code out of range. } ptr = LCD_displayData + 19; // Point to the first relevant LCDDR; 19, 14, 9, 4 for (j=0; j<4 ;j++) // Read out the 4 half-nibbles from lookupdata. { mask = 0xC0; lastnibblemask = 0x40; seg = ( lookupdata & mask ); // Variable lookupdata contains: // msb| A | B | F | G | E | C | D | |lsb (7seg) //Shift half-nibble and masks into correct location. for (i = digit-1; i>0; i--) { seg >>= 2; mask >>= 2; lastnibblemask >>= 2; } if (j == 3) //need special mask for the last half nibble since it contains only one valid bit. { mask = mask & ~lastnibblemask; } *ptr = (*ptr & ~mask) | seg; //Write new bit values. ptr -= 5; lookupdata <<= 2; //Prepare for next two bits. } } Here is the call graph for this function:

void LCD_SetSeg (  unsigned char  symbol, unsigned char  input )

Turns ON or OFF a segment in the LCD display buffer. Parameters: symbol  Use Segment Definitions from the stk504_lcd.h file input  0 will clear the bit, 1..255 will set the bit. Definition at line 308 of file stk504_lcd.c. References LCD_displayData. Referenced by LCD_PutDigit(), and main(). { unsigned char offset; unsigned char setbit; unsigned char *ptr; // Symbol format = bbbnnnnn where b is bit[0..7] and n is offset[0..19] // Valid symbols are defined in stk504_lcd.h setbit = (symbol >> 5); offset = (symbol & 0x1F); if ( offset >= 20 ) { return; //data out of range of the LCD registers } ptr = LCD_displayData + offset; // Point to the relevant LCDDR if ( input ) { *ptr = (*ptr) | ( 1 << setbit); // Set bit } else { *ptr = (*ptr) & ~( 1 << setbit); // Clear bit } }

void LCD_Update (  void   )

Moves display buffer content to LCDDR[0..19]. Allows forced update to the phyhsical LCDDR registers, instead of setting updateRequired and waiting for the interrupt to update the LCD registers. Definition at line 375 of file stk504_lcd.c. References LCD_displayData, and pLCDREG. { unsigned char *src, *dest; unsigned char i; i = 20; dest = &pLCDREG; src = LCD_displayData; do { *dest++ = *src++; } while ( --i ); }

__interrupt void LCD_vect_interrupt (  void   )

LCD Interrupt Routine to latch the LCD_displayData and Set LCD_status.updateComplete. Definition at line 425 of file stk504_lcd.c. References FALSE, LCD_displayData, LCD_timer, LCD_TIMER_SEED, pLCDREG, TRUE, _LCD_status::updateComplete, and _LCD_status::updateRequired. { unsigned char i; unsigned char *src, *dest; LCD_timer--; if( LCD_timer == 0 ) { if( LCD_status.updateRequired == TRUE ) { // PINB = 0x40; LCD_timer = LCD_TIMER_SEED; LCD_status.updateComplete = TRUE; // Set the ucLCD_ScrollReady to true. LCD_status.updateRequired = FALSE; // No furter update necessary until // another function changes buffer contents. // Latch display data buffer to I/O segment registers. i = 20; dest = &pLCDREG; src = LCD_displayData; do { *dest++ = *src++; } while ( --i ); } else { LCD_timer = 1; //If LCD timer allows update of the LCD, but update is blocked // by LCD_status.updateRequired == FALSE the LCD_timer is preloaded // with smallest timer seed to ensure fastest LCD update. LCD_status.updateComplete = FALSE; //Block for further access to the LCD_displayData until // LCD update has been performed. } } }

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Variable Documentation

__flash unsigned int LCD_character_table[]

Look-up tables for 14-segment characters. Definition at line 36 of file stk504_lcd.c. Referenced by LCD_PutChar().

__flash unsigned char LCD_digit_table[]

Look-up tables for 7-segment characters. Definition at line 95 of file stk504_lcd.c. Referenced by LCD_PutDigit().

unsigned char LCD_displayData[LCD_REGISTER_COUNT]

LCD display buffer (for double buffering). Definition at line 33 of file stk504_lcd.c. Referenced by LCD_AllSegments(), LCD_BarSeg(), LCD_PutChar(), LCD_PutDigit(), LCD_SetSeg(), LCD_Update(), and LCD_vect_interrupt().

union _LCD_status LCD_status = {0x01}

LCD_status = {0, 0, 0, 0, 0, 0, FALSE, TRUE};. Definition at line 31 of file stk504_lcd.c. Referenced by LCD_timerDelay(), and main().

unsigned char LCD_timer = LCD_TIMER_SEED

Definition at line 32 of file stk504_lcd.c. Referenced by LCD_timerDelay(), and LCD_vect_interrupt().

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