Library for interfacing to Nokia 5110 LCD display (as found on the SparkFun website).

Dependents:   LV7_LCDtest LV7_Grupa5_Tim003_Zadatak1 lv7_Grupa5_Tim008_zad1 LV7_PAI_Grupa5_tim10_Zadatak1 ... more

This library is designed to make it easy to interface an mbed with a Nokia 5110 LCD display.

These can be found at Sparkfun (https://www.sparkfun.com/products/10168) and Adafruit (http://www.adafruit.com/product/338).

The library uses the SPI peripheral on the mbed which means it is much faster sending data to the display than other libraries available on other platforms that use software SPI.

The library can print strings as well as controlling individual pixels, meaning that both text and primitive graphics can be displayed.

N5110.cpp

Committer:
eencae
Date:
9 months ago
Revision:
51:32f9ffeafb6d
Parent:
50:e73cd097fdcb

File content as of revision 51:32f9ffeafb6d:

#include "mbed.h"
#include "N5110.h"

// overloaded constructor includes power pin - LCD Vcc connected to GPIO pin
// this constructor works fine with LPC1768 - enough current sourced from GPIO
// to power LCD. Doesn't work well with K64F.
N5110::N5110(PinName const pwrPin,
             PinName const scePin,
             PinName const rstPin,
             PinName const dcPin,
             PinName const mosiPin,
             PinName const sclkPin,
             PinName const ledPin)
    :
    _spi(new SPI(mosiPin,NC,sclkPin)), // create new SPI instance and initialise
    _led(new PwmOut(ledPin)),
    _pwr(new DigitalOut(pwrPin)),
    _sce(new DigitalOut(scePin)),
    _rst(new DigitalOut(rstPin)),
    _dc(new DigitalOut(dcPin))
{}

// overloaded constructor does not include power pin - LCD Vcc must be tied to +3V3
// Best to use this with K64F as the GPIO hasn't sufficient output current to reliably
// drive the LCD.
N5110::N5110(PinName const scePin,
             PinName const rstPin,
             PinName const dcPin,
             PinName const mosiPin,
             PinName const sclkPin,
             PinName const ledPin)
    :
    _spi(new SPI(mosiPin,NC,sclkPin)), // create new SPI instance and initialise
    _led(new PwmOut(ledPin)),
    _pwr(NULL), // pwr not needed so null it to be safe
    _sce(new DigitalOut(scePin)),
    _rst(new DigitalOut(rstPin)),
    _dc(new DigitalOut(dcPin))
{}

N5110::~N5110()
{
    delete _spi;

    if(_pwr) {
        delete _pwr;
    }

    delete _led;
    delete _sce;
    delete _rst;
    delete _dc;
}

// initialise function - powers up and sends the initialisation commands
void N5110::init()
{
    turnOn();     // power up
    reset();      // reset LCD - must be done within 100 ms
    initSPI();    
    
    setContrast(0.55);  // this may need tuning (say 0.4 to 0.6)
    setBias(3);   // datasheet - 48:1 mux - don't mess with if you don't know what you're doing! (0 to 7)
    setTempCoefficient(0); // datasheet - may need increasing (range 0 to 3) at very low temperatures
    normalMode();  // normal video mode by default
    
    clearRAM();      // RAM is undefined at power-up so clear to be sure
    clear();   // clear buffer
    setBrightness(0.5);
}

// sets normal video mode (black on white)
void N5110::normalMode()
{
    sendCommand(0b00100000);   // basic instruction
    sendCommand(0b00001100);  // normal video mode- datasheet
}

// sets normal video mode (white on black)
void N5110::inverseMode()
{
    sendCommand(0b00100000);   // basic instruction
    sendCommand(0b00001101);   // inverse video mode - datasheet
}

// function to power up the LCD and backlight - only works when using GPIO to power
void N5110::turnOn()
{
    if (_pwr != NULL) {
        _pwr->write(1);  // apply power
    }
}

// function to power down LCD
void N5110::turnOff()
{
    clear(); // clear buffer
    refresh();
    setBrightness(0.0);  // turn backlight off
    clearRAM();   // clear RAM to ensure specified current consumption
    // send command to ensure we are in basic mode
    
    sendCommand(0b00100000); // basic mode
    sendCommand(0b00001000); // clear display
    sendCommand(0b00100001); // extended mode
    sendCommand(0b00100100); // power down
    
    // if we are powering the LCD using the GPIO then make it low to turn off
    if (_pwr != NULL) {
        wait_ms(10);  // small delay and then turn off the power pin
        _pwr->write(0);  // turn off power
    }

}

// function to change LED backlight brightness
void N5110::setBrightness(float brightness)
{
    // check whether brightness is within range
    if (brightness < 0.0f)
        brightness = 0.0f;
    if (brightness > 1.0f)
        brightness = 1.0f;
    // set PWM duty cycle
    _led->write(brightness);
}

void N5110::setContrast(float contrast) {
    
    // enforce limits
    if (contrast > 1.0f)
        contrast = 1.0f;
    else if (contrast < 0.0f)
        contrast = 0.0;
    
    // convert to char in range 0 to 127 (i.e. 6 bits)
    char ic = char(contrast*127.0f);
    
    sendCommand(0b00100001);  // extended instruction set
    sendCommand(0b10000000 | ic);   // set Vop (which controls contrast)
    sendCommand(0b00100000);  // back to basic instruction set
}

void N5110::setTempCoefficient(char tc) {
    
    // enforce limits
    if (tc>3) {
        tc=3;
    }
    
    // temperature coefficient may need increasing at low temperatures

    sendCommand(0b00100001);  // extended instruction set
    sendCommand(0b00000100 | tc);
    sendCommand(0b00100000);  // back to basic instruction set
}
    
void N5110::setBias(char bias) {
    
    // from data sheet
    // bias      mux rate
    // 0        1:100
    // 1        1:80
    // 2        1:65
    // 3        1:48   (default)
    // 4        1:40/1:34
    // 5        1:24
    // 6        1:18/1:16
    // 7        1:10/1:9/1:8
    
    // enforce limits
    if (bias>7) {
        bias=7;
    }
        
    sendCommand(0b00100001);  // extended mode instruction
    sendCommand(0b00010000 | bias);  
    sendCommand(0b00100000); // end of extended mode instruction
}

// pulse the active low reset line
void N5110::reset()
{
    _rst->write(0);  // reset the LCD
    _rst->write(1);
}

// function to initialise SPI peripheral
void N5110::initSPI()
{
    _spi->format(8,1);    // 8 bits, Mode 1 - polarity 0, phase 1 - base value of clock is 0, data captured on falling edge/propagated on rising edge
    _spi->frequency(4000000);  // maximum of screen is 4 MHz
}

// send a command to the display
void N5110::sendCommand(unsigned char command)
{
    _dc->write(0);  // set DC low for command
    _sce->write(0); // set CE low to begin frame
    _spi->write(command);  // send command
    _dc->write(1);  // turn back to data by default
    _sce->write(1); // set CE high to end frame (expected for transmission of single byte)
}

// send data to the display at the current XY address
// dc is set to 1 (i.e. data) after sending a command and so should
// be the default mode.
void N5110::sendData(unsigned char data)
{
    _sce->write(0);   // set CE low to begin frame
    _spi->write(data);
    _sce->write(1);  // set CE high to end frame (expected for transmission of single byte)
}

// this function writes 0 to the 504 bytes to clear the RAM
void N5110::clearRAM()
{
    _sce->write(0);  //set CE low to begin frame
    for(int i = 0; i < WIDTH * HEIGHT; i++) { // 48 x 84 bits = 504 bytes
        _spi->write(0x00);  // send 0's
    }
    _sce->write(1); // set CE high to end frame
}

// function to set the XY address in RAM for subsequenct data write
void N5110::setXYAddress(unsigned int const x,
                         unsigned int const y)
{
    if (x<WIDTH && y<HEIGHT) {  // check within range
        sendCommand(0b00100000);  // basic instruction
        sendCommand(0b10000000 | x);  // send addresses to display with relevant mask
        sendCommand(0b01000000 | y);
    }
}

// These functions are used to set, clear and get the value of pixels in the display
// Pixels are addressed in the range of 0 to 47 (y) and 0 to 83 (x).  The refresh()
// function must be called after set and clear in order to update the display
void N5110::setPixel(unsigned int const x,
                     unsigned int const y,
                     bool const         state)
{
    if (x<WIDTH && y<HEIGHT) {  // check within range
        // calculate bank and shift 1 to required position in the data byte
        if(state) buffer[x][y/8] |= (1 << y%8);
        else      buffer[x][y/8] &= ~(1 << y%8);
    }
}

void N5110::clearPixel(unsigned int const x,
                       unsigned int const y)
{
    if (x<WIDTH && y<HEIGHT) {  // check within range
        // calculate bank and shift 1 to required position (using bit clear)
        buffer[x][y/8] &= ~(1 << y%8);
    }
}

int N5110::getPixel(unsigned int const x,
                    unsigned int const y) const
{
    if (x<WIDTH && y<HEIGHT) {  // check within range
        // return relevant bank and mask required bit

        int pixel = (int) buffer[x][y/8] & (1 << y%8);

        if (pixel)
            return 1;
        else
            return 0;
    }

    return 0;

}

// function to refresh the display
void N5110::refresh()
{
    setXYAddress(0,0);  // important to set address back to 0,0 before refreshing display
    // address auto increments after printing string, so buffer[0][0] will not coincide
    // with top-left pixel after priting string

    _sce->write(0);  //set CE low to begin frame

    for(int j = 0; j < BANKS; j++) {  // be careful to use correct order (j,i) for horizontal addressing
        for(int i = 0; i < WIDTH; i++) {
            _spi->write(buffer[i][j]);  // send buffer
        }
    }
    _sce->write(1); // set CE high to end frame

}

// fills the buffer with random bytes.  Can be used to test the display.
// The rand() function isn't seeded so it probably creates the same pattern everytime
void N5110::randomiseBuffer()
{
    int i,j;
    for(j = 0; j < BANKS; j++) {  // be careful to use correct order (j,i) for horizontal addressing
        for(i = 0; i < WIDTH; i++) {
            buffer[i][j] = rand()%256;  // generate random byte
        }
    }

}

// function to print 5x7 font
void N5110::printChar(char const          c,
                      unsigned int const  x,
                      unsigned int const  y)
{
    if (y<BANKS) {  // check if printing in range of y banks

        for (int i = 0; i < 5 ; i++ ) {
            int pixel_x = x+i;
            if (pixel_x > WIDTH-1)  // ensure pixel isn't outside the buffer size (0 - 83)
                break;
            buffer[pixel_x][y] = font5x7[(c - 32)*5 + i];
            // array is offset by 32 relative to ASCII, each character is 5 pixels wide
        }

    }
}

// function to print string at specified position
void N5110::printString(const char         *str,
                        unsigned int const  x,
                        unsigned int const  y)
{
    if (y<BANKS) {  // check if printing in range of y banks

        int n = 0 ; // counter for number of characters in string
        // loop through string and print character
        while(*str) {

            // writes the character bitmap data to the buffer, so that
            // text and pixels can be displayed at the same time
            for (int i = 0; i < 5 ; i++ ) {
                int pixel_x = x+i+n*6;
                if (pixel_x > WIDTH-1) // ensure pixel isn't outside the buffer size (0 - 83)
                    break;
                buffer[pixel_x][y] = font5x7[(*str - 32)*5 + i];
            }
            str++;  // go to next character in string
            n++;    // increment index
        }
    }
}

// function to clear the screen buffer
void N5110::clear()
{
    memset(buffer,0,sizeof(buffer));
}

// function to plot array on display
void N5110::plotArray(float const array[])
{
    for (int i=0; i<WIDTH; i++) {  // loop through array
        // elements are normalised from 0.0 to 1.0, so multiply
        // by 47 to convert to pixel range, and subtract from 47
        // since top-left is 0,0 in the display geometry
        setPixel(i,47 - int(array[i]*47.0f),true);
    }

}

// function to draw circle
void N5110:: drawCircle(unsigned int const x0,
                        unsigned int const y0,
                        unsigned int const radius,
                        FillType const     fill)
{
    // from http://en.wikipedia.org/wiki/Midpoint_circle_algorithm
    int x = radius;
    int y = 0;
    int radiusError = 1-x;

    while(x >= y) {

        // if transparent, just draw outline
        if (fill == FILL_TRANSPARENT) {
            setPixel( x + x0,  y + y0,true);
            setPixel(-x + x0,  y + y0,true);
            setPixel( y + x0,  x + y0,true);
            setPixel(-y + x0,  x + y0,true);
            setPixel(-y + x0, -x + y0,true);
            setPixel( y + x0, -x + y0,true);
            setPixel( x + x0, -y + y0,true);
            setPixel(-x + x0, -y + y0,true);
        } else {  // drawing filled circle, so draw lines between points at same y value

            int type = (fill==FILL_BLACK) ? 1:0;  // black or white fill

            drawLine(x+x0,y+y0,-x+x0,y+y0,type);
            drawLine(y+x0,x+y0,-y+x0,x+y0,type);
            drawLine(y+x0,-x+y0,-y+x0,-x+y0,type);
            drawLine(x+x0,-y+y0,-x+x0,-y+y0,type);
        }

        y++;
        if (radiusError<0) {
            radiusError += 2 * y + 1;
        } else {
            x--;
            radiusError += 2 * (y - x) + 1;
        }
    }

}

void N5110::drawLine(unsigned int const x0,
                     unsigned int const y0,
                     unsigned int const x1,
                     unsigned int const y1,
                     unsigned int const type)
{
    // Note that the ranges can be negative so we have to turn the input values
    // into signed integers first
    int const y_range = static_cast<int>(y1) - static_cast<int>(y0);
    int const x_range = static_cast<int>(x1) - static_cast<int>(x0);

    // if dotted line, set step to 2, else step is 1
    unsigned int const step = (type==2) ? 2:1;

    // make sure we loop over the largest range to get the most pixels on the display
    // for instance, if drawing a vertical line (x_range = 0), we need to loop down the y pixels
    // or else we'll only end up with 1 pixel in the x column
    if ( abs(x_range) > abs(y_range) ) {

        // ensure we loop from smallest to largest or else for-loop won't run as expected
        unsigned int const start = x_range > 0 ? x0:x1;
        unsigned int const stop =  x_range > 0 ? x1:x0;

        // loop between x pixels
        for (unsigned int x = start; x<= stop ; x+=step) {
            // do linear interpolation
            int const dx = static_cast<int>(x)-static_cast<int>(x0);
            unsigned int const y = y0 + y_range * dx / x_range;

            // If the line type is '0', this will clear the pixel
            // If it is '1' or '2', the pixel will be set
            setPixel(x,y, type);
        }
    } else {

        // ensure we loop from smallest to largest or else for-loop won't run as expected
        unsigned int const start = y_range > 0 ? y0:y1;
        unsigned int const stop =  y_range > 0 ? y1:y0;

        for (unsigned int y = start; y<= stop ; y+=step) {
            // do linear interpolation
            int const dy = static_cast<int>(y)-static_cast<int>(y0);
            unsigned int const x = x0 + x_range * dy / y_range;

            // If the line type is '0', this will clear the pixel
            // If it is '1' or '2', the pixel will be set
            setPixel(x,y, type);
        }
    }

}

void N5110::drawRect(unsigned int const x0,
                     unsigned int const y0,
                     unsigned int const width,
                     unsigned int const height,
                     FillType const     fill)
{
    if (fill == FILL_TRANSPARENT) { // transparent, just outline
        drawLine(x0,y0,x0+(width-1),y0,1);  // top
        drawLine(x0,y0+(height-1),x0+(width-1),y0+(height-1),1);  // bottom
        drawLine(x0,y0,x0,y0+(height-1),1);  // left
        drawLine(x0+(width-1),y0,x0+(width-1),y0+(height-1),1);  // right
    } else { // filled rectangle
        int type = (fill==FILL_BLACK) ? 1:0;  // black or white fill
        for (int y = y0; y<y0+height; y++) {  // loop through rows of rectangle
            drawLine(x0,y,x0+(width-1),y,type);  // draw line across screen
        }
    }
}

void N5110::drawSprite(int x0,
                       int y0,
                       int nrows,
                       int ncols,
                       int *sprite)
{
    for (int i = 0; i < nrows; i++) {
        for (int j = 0 ; j < ncols ; j++) {

            int pixel = *((sprite+i*ncols)+j);
            setPixel(x0+j,y0+i, pixel);
        }
    }
}