LCD_driver.c File Reference

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Detailed Description

Functions used to control the STK502 LCD.

Application note:

AVR065: LCD Driver for the STK502

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

LCD_driver.c,v

Date

2006/02/16 18:14:01

Definition in file LCD_driver.c.

#include "defines.h"
#include "LCD_driver.h"

Include dependency graph for LCD_driver.c:

Go to the source code of this file.

Functions
void	LCD_AllSegments (unsigned char input)
	display all or hide all LCD segments on the STK502 LCD.
void	LCD_Init (void)
	Initialize LCD_displayData buffer. Set up the LCD (timing, contrast, etc.).
__interrupt void	LCD_SOF_interrupt (void)
	Latch the LCD_displayData and Set LCD_status.updateComplete.
void	LCD_WriteDigit (unsigned char c, unsigned char digit)
	Stores LCD control data in the LCD_displayData buffer. (The LCD_displayData is latched in the LCD_SOF interrupt).
Variables
__flash unsigned int	LCD_character_table []
	Look-up table used when converting ASCII to LCD display data (segment control).
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
	Determine the delay to next LCD update.

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Function Documentation

void LCD_AllSegments (  unsigned char  input  )

display all or hide all LCD segments on the STK502 LCD. Parameters: input  - [TRUE;FALSE]=[DISPLAY;HIDE]. Definition at line 176 of file LCD_driver.c. References LCD_displayData. Referenced by LCD_Init(). { unsigned char i; unsigned char *ptr; if( input ) // if input == TRUE input = 0xFF; // set setgemts to 0xFF // (else set segments to 0x00) ptr = LCD_displayData; i = 20; do // Set all LCD segment register to the variable ucSegments { *ptr++ = input; // Set/clear the bits in all LCD registers } while ( --i ); }

void LCD_Init (  void   )

Initialize LCD_displayData buffer. Set up the LCD (timing, contrast, etc.). Definition at line 98 of file LCD_driver.c. References FALSE, LCD_AllSegments(), LCD_CONTRAST_LEVEL, and LCD_INITIAL_CONTRAST. Referenced by main(). { LCD_AllSegments( FALSE ); // Clear segment buffer. 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<<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:

__interrupt void LCD_SOF_interrupt (  void   )

Latch the LCD_displayData and Set LCD_status.updateComplete. Definition at line 197 of file LCD_driver.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 ) { LCD_timer = LCD_TIMER_SEED; LCD_status.updateComplete = TRUE; // Set the ucLCD_ScrollReady to true. // Copy 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. } } }

void LCD_WriteDigit (  unsigned char  c, unsigned char  digit )

Stores LCD control data in the LCD_displayData buffer. (The LCD_displayData is latched in the LCD_SOF interrupt). Parameters: c  - The symbol to be displayed in a LCD digit. digit  - The LCD digit that the symbol should be displayed in. Definition at line 119 of file LCD_driver.c. References LCD_character_table, and LCD_displayData. Referenced by main(). { unsigned int seg; unsigned char i; unsigned char mask, nibble; unsigned char *ptr; //Lookup character table for segmet data seg = 0x0000; if ( (c >= '*') && (c <= 'z') ) { // c is in character_table. // Convert to upper if necessarry. if ( c >= 'a' ) c &= ~0x20; c -= '*'; seg = LCD_character_table[c]; } else { return; //ASCII code out of range } // Adjust mask according to digit mask = 0x0F; // (1), 3, 5, 7 if ( digit & 0x01 ) { //left empty to optimize code size } else { mask = 0xF0; // (0), 2, 4, 6 } i = digit-2; //i used as pointer offset if ( i >= 6 ) //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; seg >>= 4; if ( digit & 0x01 ) nibble <<= 4; *ptr = (*ptr & mask) | nibble; ptr += 5; } while ( --i ); }

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Variable Documentation

__flash unsigned int LCD_character_table[]

Look-up table used when converting ASCII to LCD display data (segment control). Definition at line 37 of file LCD_driver.c. Referenced by LCD_WriteDigit().

unsigned char LCD_displayData[LCD_REGISTER_COUNT]

LCD display buffer (for double buffering). Definition at line 34 of file LCD_driver.c. Referenced by LCD_AllSegments(), LCD_SOF_interrupt(), and LCD_WriteDigit().

union _LCD_status LCD_status = {0x01}

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

unsigned char LCD_timer = LCD_TIMER_SEED

Determine the delay to next LCD update. Definition at line 32 of file LCD_driver.c. Referenced by LCD_SOF_interrupt(), and LCD_timerDelay().

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