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

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Show/hide line numbers <title>N5110.cpp Source File</title>

N5110.cpp

00001 #include "mbed.h"
00002 #include "N5110.h"
00003 
00004 // overloaded constructor includes power pin - LCD Vcc connected to GPIO pin
00005 // this constructor works fine with LPC1768 - enough current sourced from GPIO
00006 // to power LCD. Doesn't work well with K64F.
00007 N5110::N5110(PinName const pwrPin,
00008              PinName const scePin,
00009              PinName const rstPin,
00010              PinName const dcPin,
00011              PinName const mosiPin,
00012              PinName const sclkPin,
00013              PinName const ledPin)
00014     :
00015     _spi(new SPI(mosiPin,NC,sclkPin)), // create new SPI instance and initialise
00016     _led(new PwmOut(ledPin)),
00017     _pwr(new DigitalOut(pwrPin)),
00018     _sce(new DigitalOut(scePin)),
00019     _rst(new DigitalOut(rstPin)),
00020     _dc(new DigitalOut(dcPin))
00021 {}
00022 
00023 // overloaded constructor does not include power pin - LCD Vcc must be tied to +3V3
00024 // Best to use this with K64F as the GPIO hasn't sufficient output current to reliably
00025 // drive the LCD.
00026 N5110::N5110(PinName const scePin,
00027              PinName const rstPin,
00028              PinName const dcPin,
00029              PinName const mosiPin,
00030              PinName const sclkPin,
00031              PinName const ledPin)
00032     :
00033     _spi(new SPI(mosiPin,NC,sclkPin)), // create new SPI instance and initialise
00034     _led(new PwmOut(ledPin)),
00035     _pwr(NULL), // pwr not needed so null it to be safe
00036     _sce(new DigitalOut(scePin)),
00037     _rst(new DigitalOut(rstPin)),
00038     _dc(new DigitalOut(dcPin))
00039 {}
00040 
00041 N5110::~N5110()
00042 {
00043     delete _spi;
00044 
00045     if(_pwr) {
00046         delete _pwr;
00047     }
00048 
00049     delete _led;
00050     delete _sce;
00051     delete _rst;
00052     delete _dc;
00053 }
00054 
00055 // initialise function - powers up and sends the initialisation commands
00056 void N5110::init()
00057 {
00058     turnOn();     // power up
00059     reset();      // reset LCD - must be done within 100 ms
00060     initSPI();    
00061     
00062     setContrast(0.55);  // this may need tuning (say 0.4 to 0.6)
00063     setBias(3);   // datasheet - 48:1 mux - don't mess with if you don't know what you're doing! (0 to 7)
00064     setTempCoefficient(0); // datasheet - may need increasing (range 0 to 3) at very low temperatures
00065     normalMode();  // normal video mode by default
00066     
00067     clearRAM();      // RAM is undefined at power-up so clear to be sure
00068     clear();   // clear buffer
00069     setBrightness(0.5);
00070 }
00071 
00072 // sets normal video mode (black on white)
00073 void N5110::normalMode()
00074 {
00075     sendCommand(0b00100000);   // basic instruction
00076     sendCommand(0b00001100);  // normal video mode- datasheet
00077 }
00078 
00079 // sets normal video mode (white on black)
00080 void N5110::inverseMode()
00081 {
00082     sendCommand(0b00100000);   // basic instruction
00083     sendCommand(0b00001101);   // inverse video mode - datasheet
00084 }
00085 
00086 // function to power up the LCD and backlight - only works when using GPIO to power
00087 void N5110::turnOn()
00088 {
00089     if (_pwr != NULL) {
00090         _pwr->write(1);  // apply power
00091     }
00092 }
00093 
00094 // function to power down LCD
00095 void N5110::turnOff()
00096 {
00097     clear(); // clear buffer
00098     refresh();
00099     setBrightness(0.0);  // turn backlight off
00100     clearRAM();   // clear RAM to ensure specified current consumption
00101     // send command to ensure we are in basic mode
00102     
00103     sendCommand(0b00100000); // basic mode
00104     sendCommand(0b00001000); // clear display
00105     sendCommand(0b00100001); // extended mode
00106     sendCommand(0b00100100); // power down
00107     
00108     // if we are powering the LCD using the GPIO then make it low to turn off
00109     if (_pwr != NULL) {
00110         wait_ms(10);  // small delay and then turn off the power pin
00111         _pwr->write(0);  // turn off power
00112     }
00113 
00114 }
00115 
00116 // function to change LED backlight brightness
00117 void N5110::setBrightness(float brightness)
00118 {
00119     // check whether brightness is within range
00120     if (brightness < 0.0f)
00121         brightness = 0.0f;
00122     if (brightness > 1.0f)
00123         brightness = 1.0f;
00124     // set PWM duty cycle
00125     _led->write(brightness);
00126 }
00127 
00128 void N5110::setContrast(float contrast) {
00129     
00130     // enforce limits
00131     if (contrast > 1.0f)
00132         contrast = 1.0f;
00133     else if (contrast < 0.0f)
00134         contrast = 0.0;
00135     
00136     // convert to char in range 0 to 127 (i.e. 6 bits)
00137     char ic = char(contrast*127.0f);
00138     
00139     sendCommand(0b00100001);  // extended instruction set
00140     sendCommand(0b10000000 | ic);   // set Vop (which controls contrast)
00141     sendCommand(0b00100000);  // back to basic instruction set
00142 }
00143 
00144 void N5110::setTempCoefficient(char tc) {
00145     
00146     // enforce limits
00147     if (tc>3) {
00148         tc=3;
00149     }
00150     
00151     // temperature coefficient may need increasing at low temperatures
00152 
00153     sendCommand(0b00100001);  // extended instruction set
00154     sendCommand(0b00000100 | tc);
00155     sendCommand(0b00100000);  // back to basic instruction set
00156 }
00157     
00158 void N5110::setBias(char bias) {
00159     
00160     // from data sheet
00161     // bias      mux rate
00162     // 0        1:100
00163     // 1        1:80
00164     // 2        1:65
00165     // 3        1:48   (default)
00166     // 4        1:40/1:34
00167     // 5        1:24
00168     // 6        1:18/1:16
00169     // 7        1:10/1:9/1:8
00170     
00171     // enforce limits
00172     if (bias>7) {
00173         bias=7;
00174     }
00175         
00176     sendCommand(0b00100001);  // extended mode instruction
00177     sendCommand(0b00010000 | bias);  
00178     sendCommand(0b00100000); // end of extended mode instruction
00179 }
00180 
00181 // pulse the active low reset line
00182 void N5110::reset()
00183 {
00184     _rst->write(0);  // reset the LCD
00185     _rst->write(1);
00186 }
00187 
00188 // function to initialise SPI peripheral
00189 void N5110::initSPI()
00190 {
00191     _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
00192     _spi->frequency(4000000);  // maximum of screen is 4 MHz
00193 }
00194 
00195 // send a command to the display
00196 void N5110::sendCommand(unsigned char command)
00197 {
00198     _dc->write(0);  // set DC low for command
00199     _sce->write(0); // set CE low to begin frame
00200     _spi->write(command);  // send command
00201     _dc->write(1);  // turn back to data by default
00202     _sce->write(1); // set CE high to end frame (expected for transmission of single byte)
00203 }
00204 
00205 // send data to the display at the current XY address
00206 // dc is set to 1 (i.e. data) after sending a command and so should
00207 // be the default mode.
00208 void N5110::sendData(unsigned char data)
00209 {
00210     _sce->write(0);   // set CE low to begin frame
00211     _spi->write(data);
00212     _sce->write(1);  // set CE high to end frame (expected for transmission of single byte)
00213 }
00214 
00215 // this function writes 0 to the 504 bytes to clear the RAM
00216 void N5110::clearRAM()
00217 {
00218     _sce->write(0);  //set CE low to begin frame
00219     for(int i = 0; i < WIDTH * HEIGHT; i++) { // 48 x 84 bits = 504 bytes
00220         _spi->write(0x00);  // send 0's
00221     }
00222     _sce->write(1); // set CE high to end frame
00223 }
00224 
00225 // function to set the XY address in RAM for subsequenct data write
00226 void N5110::setXYAddress(unsigned int const x,
00227                          unsigned int const y)
00228 {
00229     if (x<WIDTH && y<HEIGHT) {  // check within range
00230         sendCommand(0b00100000);  // basic instruction
00231         sendCommand(0b10000000 | x);  // send addresses to display with relevant mask
00232         sendCommand(0b01000000 | y);
00233     }
00234 }
00235 
00236 // These functions are used to set, clear and get the value of pixels in the display
00237 // Pixels are addressed in the range of 0 to 47 (y) and 0 to 83 (x).  The refresh()
00238 // function must be called after set and clear in order to update the display
00239 void N5110::setPixel(unsigned int const x,
00240                      unsigned int const y,
00241                      bool const         state)
00242 {
00243     if (x<WIDTH && y<HEIGHT) {  // check within range
00244         // calculate bank and shift 1 to required position in the data byte
00245         if(state) buffer[x][y/8] |= (1 << y%8);
00246         else      buffer[x][y/8] &= ~(1 << y%8);
00247     }
00248 }
00249 
00250 void N5110::clearPixel(unsigned int const x,
00251                        unsigned int const y)
00252 {
00253     if (x<WIDTH && y<HEIGHT) {  // check within range
00254         // calculate bank and shift 1 to required position (using bit clear)
00255         buffer[x][y/8] &= ~(1 << y%8);
00256     }
00257 }
00258 
00259 int N5110::getPixel(unsigned int const x,
00260                     unsigned int const y) const
00261 {
00262     if (x<WIDTH && y<HEIGHT) {  // check within range
00263         // return relevant bank and mask required bit
00264 
00265         int pixel = (int) buffer[x][y/8] & (1 << y%8);
00266 
00267         if (pixel)
00268             return 1;
00269         else
00270             return 0;
00271     }
00272 
00273     return 0;
00274 
00275 }
00276 
00277 // function to refresh the display
00278 void N5110::refresh()
00279 {
00280     setXYAddress(0,0);  // important to set address back to 0,0 before refreshing display
00281     // address auto increments after printing string, so buffer[0][0] will not coincide
00282     // with top-left pixel after priting string
00283 
00284     _sce->write(0);  //set CE low to begin frame
00285 
00286     for(int j = 0; j < BANKS; j++) {  // be careful to use correct order (j,i) for horizontal addressing
00287         for(int i = 0; i < WIDTH; i++) {
00288             _spi->write(buffer[i][j]);  // send buffer
00289         }
00290     }
00291     _sce->write(1); // set CE high to end frame
00292 
00293 }
00294 
00295 // fills the buffer with random bytes.  Can be used to test the display.
00296 // The rand() function isn't seeded so it probably creates the same pattern everytime
00297 void N5110::randomiseBuffer()
00298 {
00299     int i,j;
00300     for(j = 0; j < BANKS; j++) {  // be careful to use correct order (j,i) for horizontal addressing
00301         for(i = 0; i < WIDTH; i++) {
00302             buffer[i][j] = rand()%256;  // generate random byte
00303         }
00304     }
00305 
00306 }
00307 
00308 // function to print 5x7 font
00309 void N5110::printChar(char const          c,
00310                       unsigned int const  x,
00311                       unsigned int const  y)
00312 {
00313     if (y<BANKS) {  // check if printing in range of y banks
00314 
00315         for (int i = 0; i < 5 ; i++ ) {
00316             int pixel_x = x+i;
00317             if (pixel_x > WIDTH-1)  // ensure pixel isn't outside the buffer size (0 - 83)
00318                 break;
00319             buffer[pixel_x][y] = font5x7[(c - 32)*5 + i];
00320             // array is offset by 32 relative to ASCII, each character is 5 pixels wide
00321         }
00322 
00323     }
00324 }
00325 
00326 // function to print string at specified position
00327 void N5110::printString(const char         *str,
00328                         unsigned int const  x,
00329                         unsigned int const  y)
00330 {
00331     if (y<BANKS) {  // check if printing in range of y banks
00332 
00333         int n = 0 ; // counter for number of characters in string
00334         // loop through string and print character
00335         while(*str) {
00336 
00337             // writes the character bitmap data to the buffer, so that
00338             // text and pixels can be displayed at the same time
00339             for (int i = 0; i < 5 ; i++ ) {
00340                 int pixel_x = x+i+n*6;
00341                 if (pixel_x > WIDTH-1) // ensure pixel isn't outside the buffer size (0 - 83)
00342                     break;
00343                 buffer[pixel_x][y] = font5x7[(*str - 32)*5 + i];
00344             }
00345             str++;  // go to next character in string
00346             n++;    // increment index
00347         }
00348     }
00349 }
00350 
00351 // function to clear the screen buffer
00352 void N5110::clear()
00353 {
00354     memset(buffer,0,sizeof(buffer));
00355 }
00356 
00357 // function to plot array on display
00358 void N5110::plotArray(float const array[])
00359 {
00360     for (int i=0; i<WIDTH; i++) {  // loop through array
00361         // elements are normalised from 0.0 to 1.0, so multiply
00362         // by 47 to convert to pixel range, and subtract from 47
00363         // since top-left is 0,0 in the display geometry
00364         setPixel(i,47 - int(array[i]*47.0f),true);
00365     }
00366 
00367 }
00368 
00369 // function to draw circle
00370 void N5110:: drawCircle(unsigned int const x0,
00371                         unsigned int const y0,
00372                         unsigned int const radius,
00373                         FillType const     fill)
00374 {
00375     // from http://en.wikipedia.org/wiki/Midpoint_circle_algorithm
00376     int x = radius;
00377     int y = 0;
00378     int radiusError = 1-x;
00379 
00380     while(x >= y) {
00381 
00382         // if transparent, just draw outline
00383         if (fill == FILL_TRANSPARENT) {
00384             setPixel( x + x0,  y + y0,true);
00385             setPixel(-x + x0,  y + y0,true);
00386             setPixel( y + x0,  x + y0,true);
00387             setPixel(-y + x0,  x + y0,true);
00388             setPixel(-y + x0, -x + y0,true);
00389             setPixel( y + x0, -x + y0,true);
00390             setPixel( x + x0, -y + y0,true);
00391             setPixel(-x + x0, -y + y0,true);
00392         } else {  // drawing filled circle, so draw lines between points at same y value
00393 
00394             int type = (fill==FILL_BLACK) ? 1:0;  // black or white fill
00395 
00396             drawLine(x+x0,y+y0,-x+x0,y+y0,type);
00397             drawLine(y+x0,x+y0,-y+x0,x+y0,type);
00398             drawLine(y+x0,-x+y0,-y+x0,-x+y0,type);
00399             drawLine(x+x0,-y+y0,-x+x0,-y+y0,type);
00400         }
00401 
00402         y++;
00403         if (radiusError<0) {
00404             radiusError += 2 * y + 1;
00405         } else {
00406             x--;
00407             radiusError += 2 * (y - x) + 1;
00408         }
00409     }
00410 
00411 }
00412 
00413 void N5110::drawLine(unsigned int const x0,
00414                      unsigned int const y0,
00415                      unsigned int const x1,
00416                      unsigned int const y1,
00417                      unsigned int const type)
00418 {
00419     // Note that the ranges can be negative so we have to turn the input values
00420     // into signed integers first
00421     int const y_range = static_cast<int>(y1) - static_cast<int>(y0);
00422     int const x_range = static_cast<int>(x1) - static_cast<int>(x0);
00423 
00424     // if dotted line, set step to 2, else step is 1
00425     unsigned int const step = (type==2) ? 2:1;
00426 
00427     // make sure we loop over the largest range to get the most pixels on the display
00428     // for instance, if drawing a vertical line (x_range = 0), we need to loop down the y pixels
00429     // or else we'll only end up with 1 pixel in the x column
00430     if ( abs(x_range) > abs(y_range) ) {
00431 
00432         // ensure we loop from smallest to largest or else for-loop won't run as expected
00433         unsigned int const start = x_range > 0 ? x0:x1;
00434         unsigned int const stop =  x_range > 0 ? x1:x0;
00435 
00436         // loop between x pixels
00437         for (unsigned int x = start; x<= stop ; x+=step) {
00438             // do linear interpolation
00439             int const dx = static_cast<int>(x)-static_cast<int>(x0);
00440             unsigned int const y = y0 + y_range * dx / x_range;
00441 
00442             // If the line type is '0', this will clear the pixel
00443             // If it is '1' or '2', the pixel will be set
00444             setPixel(x,y, type);
00445         }
00446     } else {
00447 
00448         // ensure we loop from smallest to largest or else for-loop won't run as expected
00449         unsigned int const start = y_range > 0 ? y0:y1;
00450         unsigned int const stop =  y_range > 0 ? y1:y0;
00451 
00452         for (unsigned int y = start; y<= stop ; y+=step) {
00453             // do linear interpolation
00454             int const dy = static_cast<int>(y)-static_cast<int>(y0);
00455             unsigned int const x = x0 + x_range * dy / y_range;
00456 
00457             // If the line type is '0', this will clear the pixel
00458             // If it is '1' or '2', the pixel will be set
00459             setPixel(x,y, type);
00460         }
00461     }
00462 
00463 }
00464 
00465 void N5110::drawRect(unsigned int const x0,
00466                      unsigned int const y0,
00467                      unsigned int const width,
00468                      unsigned int const height,
00469                      FillType const     fill)
00470 {
00471     if (fill == FILL_TRANSPARENT) { // transparent, just outline
00472         drawLine(x0,y0,x0+(width-1),y0,1);  // top
00473         drawLine(x0,y0+(height-1),x0+(width-1),y0+(height-1),1);  // bottom
00474         drawLine(x0,y0,x0,y0+(height-1),1);  // left
00475         drawLine(x0+(width-1),y0,x0+(width-1),y0+(height-1),1);  // right
00476     } else { // filled rectangle
00477         int type = (fill==FILL_BLACK) ? 1:0;  // black or white fill
00478         for (int y = y0; y<y0+height; y++) {  // loop through rows of rectangle
00479             drawLine(x0,y,x0+(width-1),y,type);  // draw line across screen
00480         }
00481     }
00482 }
00483 
00484 void N5110::drawSprite(int x0,
00485                        int y0,
00486                        int nrows,
00487                        int ncols,
00488                        int *sprite)
00489 {
00490     for (int i = 0; i < nrows; i++) {
00491         for (int j = 0 ; j < ncols ; j++) {
00492 
00493             int pixel = *((sprite+i*ncols)+j);
00494             setPixel(x0+j,y0+i, pixel);
00495         }
00496     }
00497 }