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.

Revision:
23:eb7e6632fc9e
Parent:
22:31c54fc61f12
Child:
24:342bdb6679a1
diff -r 31c54fc61f12 -r eb7e6632fc9e N5110.cpp
--- a/N5110.cpp	Wed Feb 01 12:48:13 2017 +0000
+++ b/N5110.cpp	Wed Feb 01 16:26:22 2017 +0000
@@ -12,15 +12,16 @@
 // to power LCD. Doesn't work well with K64F.
 N5110::N5110(PinName pwrPin, PinName scePin, PinName rstPin, PinName dcPin, PinName mosiPin, PinName sclkPin, PinName ledPin)
 {
-    spi = new SPI(mosiPin,NC,sclkPin); // create new SPI instance and initialise
+  spi = new SPI(mosiPin,NC,sclkPin); // create new SPI instance and initialise
 
-    // set up pins as required
-    led = new PwmOut(ledPin);
-    pwr = new DigitalOut(pwrPin);
-    sce = new DigitalOut(scePin);
-    rst = new DigitalOut(rstPin);
-    dc = new DigitalOut(dcPin);
+  // set up pins as required
+  led = new PwmOut(ledPin);
+  pwr = new DigitalOut(pwrPin);
+  sce = new DigitalOut(scePin);
+  rst = new DigitalOut(rstPin);
+  dc = new DigitalOut(dcPin);
 
+  clearBuffer();
 }
 
 // overloaded constructor does not include power pin - LCD Vcc must be tied to +3V3
@@ -28,126 +29,121 @@
 // drive the LCD.
 N5110::N5110(PinName scePin, PinName rstPin, PinName dcPin, PinName mosiPin, PinName sclkPin, PinName ledPin)
 {
-    spi = new SPI(mosiPin,NC,sclkPin); // create new SPI instance and initialise
+  spi = new SPI(mosiPin,NC,sclkPin); // create new SPI instance and initialise
+  // set up pins as required
+  pwr = NULL;
+  led = new PwmOut(ledPin);
+  sce = new DigitalOut(scePin);
+  rst = new DigitalOut(rstPin);
+  dc = new DigitalOut(dcPin);
 
-    // set up pins as required
-    led = new PwmOut(ledPin);
-    sce = new DigitalOut(scePin);
-    rst = new DigitalOut(rstPin);
-    dc = new DigitalOut(dcPin);
+  clearBuffer();
 
 }
 
 // initialise function - powers up and sends the initialisation commands
 void N5110::init()
 {
-    initSPI();
-
-    turnOn();     // power up
-    wait_ms(10);  // small delay seems to prevent spurious pixels during mbed reset
-    reset();      // reset LCD - must be done within 100 ms
+  turnOn();     // power up
+  reset();      // reset LCD - must be done within 100 ms
 
-    // function set - extended
-    sendCommand(0x20 | CMD_FS_ACTIVE_MODE | CMD_FS_HORIZONTAL_MODE | CMD_FS_EXTENDED_MODE);
-    // Don't completely understand these parameters - they seem to work as they are
-    // Consult the datasheet if you need to change them
-    sendCommand(CMD_VOP_7V38);    // operating voltage - these values are from Chris Yan's Library
-    sendCommand(CMD_TC_TEMP_2);   // temperature control
-    sendCommand(CMD_BI_MUX_48);   // bias
+  initSPI();
+  // function set - extended
+  sendCommand(0x20 | CMD_FS_ACTIVE_MODE | CMD_FS_HORIZONTAL_MODE | CMD_FS_EXTENDED_MODE);
+  //printf("*");
+  // Don't completely understand these parameters - they seem to work as they are
+  // Consult the datasheet if you need to change them
+  sendCommand(CMD_VOP_7V38);    // operating voltage - these values are from Chris Yan's Library
+  sendCommand(CMD_TC_TEMP_2);   // temperature control
+  sendCommand(CMD_BI_MUX_48);   // bias
 
-    // function set - basic
-    sendCommand(0x20 | CMD_FS_ACTIVE_MODE | CMD_FS_HORIZONTAL_MODE | CMD_FS_BASIC_MODE);
-    normalMode();  // normal video mode by default
-    sendCommand(CMD_DC_NORMAL_MODE);  // black on white
+  // function set - basic
+  sendCommand(0x20 | CMD_FS_ACTIVE_MODE | CMD_FS_HORIZONTAL_MODE | CMD_FS_BASIC_MODE);
+  normalMode();  // normal video mode by default
+  sendCommand(CMD_DC_NORMAL_MODE);  // black on white
 
-    // RAM is undefined at power-up so clear
-    clearRAM();
-
+  // RAM is undefined at power-up so clear
+  clearRAM();
+  clear();
+  setBrightness(0.5);
 }
 
 // sets normal video mode (black on white)
 void N5110::normalMode()
 {
-    sendCommand(CMD_DC_NORMAL_MODE);
-
+  sendCommand(CMD_DC_NORMAL_MODE);
 }
 
 // sets normal video mode (white on black)
 void N5110::inverseMode()
 {
-    sendCommand(CMD_DC_INVERT_VIDEO);
+  sendCommand(CMD_DC_INVERT_VIDEO);
 }
 
 // function to power up the LCD and backlight
 void N5110::turnOn()
 {
-    // set brightness of LED - 0.0 to 1.0 - default is 50%
-    setBrightness(0.5);
-
-    // if we are powering the LCD using the GPIO then make it high to turn on
-    // DigitalOut pointer won't be NULL if we used the constructor with power pin
-    if (pwr != NULL) {
-        pwr->write(1);  // apply power
-    }
+  if (pwr != NULL) {
+    pwr->write(1);  // apply power
+  }
 }
 
 // function to power down LCD
 void N5110::turnOff()
 {
-    setBrightness(0.0);  // turn backlight off
-    clearRAM();   // clear RAM to ensure specified current consumption
-    // send command to ensure we are in basic mode
-    sendCommand(0x20 | CMD_FS_ACTIVE_MODE | CMD_FS_HORIZONTAL_MODE | CMD_FS_BASIC_MODE);
-    // clear the display
-    sendCommand(CMD_DC_CLEAR_DISPLAY);
-    // enter the extended mode and power down
-    sendCommand(0x20 | CMD_FS_POWER_DOWN_MODE | CMD_FS_HORIZONTAL_MODE | CMD_FS_EXTENDED_MODE);
-    // small delay and then turn off the power pin
-    wait_ms(10);
-    
-    // if we are powering the LCD using the GPIO then make it low to turn off
-    // DigitalOut pointer won't be NULL if we used the constructor with power pin
-    if (pwr != NULL) {
-        pwr->write(0);  // turn off power
-    }
+  setBrightness(0.0);  // turn backlight off
+  clearRAM();   // clear RAM to ensure specified current consumption
+  // send command to ensure we are in basic mode
+  sendCommand(0x20 | CMD_FS_ACTIVE_MODE | CMD_FS_HORIZONTAL_MODE | CMD_FS_BASIC_MODE);
+  // clear the display
+  sendCommand(CMD_DC_CLEAR_DISPLAY);
+  // enter the extended mode and power down
+  sendCommand(0x20 | CMD_FS_POWER_DOWN_MODE | CMD_FS_HORIZONTAL_MODE | CMD_FS_EXTENDED_MODE);
+  // small delay and then turn off the power pin
+  wait_ms(10);
+
+  // if we are powering the LCD using the GPIO then make it low to turn off
+  if (pwr != NULL) {
+    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);
+  // 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);
 }
 
 
 // pulse the active low reset line
 void N5110::reset()
 {
-    rst->write(0);  // reset the LCD
-    rst->write(1);
+  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
+  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)
+  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)
 
 }
 
@@ -156,30 +152,29 @@
 // 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)
+  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()
 {
-    int i;
-    sce->write(0);  //set CE low to begin frame
-    for(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
+  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(int x, int y)
 {
-    if (x>=0 && x<WIDTH && y>=0 && y<HEIGHT) {  // check within range
-        sendCommand(0x80 | x);  // send addresses to display with relevant mask
-        sendCommand(0x40 | y);
-    }
+  if (x>=0 && x<WIDTH && y>=0 && y<HEIGHT) {  // check within range
+    sendCommand(0x80 | x);  // send addresses to display with relevant mask
+    sendCommand(0x40 | y);
+  }
 }
 
 // These functions are used to set, clear and get the value of pixels in the display
@@ -187,48 +182,47 @@
 // function must be called after set and clear in order to update the display
 void N5110::setPixel(int x, int y)
 {
-    if (x>=0 && x<WIDTH && y>=0 && y<HEIGHT) {  // check within range
-        // calculate bank and shift 1 to required position in the data byte
-        buffer[x][y/8] |= (1 << y%8);
-    }
+  if (x>=0 && x<WIDTH && y>=0 && y<HEIGHT) {  // check within range
+    // calculate bank and shift 1 to required position in the data byte
+    buffer[x][y/8] |= (1 << y%8);
+  }
 }
 
 void N5110::clearPixel(int x, int y)
 {
-    if (x>=0 && x<WIDTH && y>=0 && y<HEIGHT) {  // check within range
-        // calculate bank and shift 1 to required position (using bit clear)
-        buffer[x][y/8] &= ~(1 << y%8);
-    }
+  if (x>=0 && x<WIDTH && y>=0 && 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(int x, int y)
 {
-    if (x>=0 && x<WIDTH && y>=0 && y<HEIGHT) {  // check within range
-        // return relevant bank and mask required bit
-        return (int) buffer[x][y/8] & (1 << y%8);
-        // note this does not necessarily return 1 - a non-zero number represents a pixel
-    } else {
-        return 0;
-    }
+  if (x>=0 && x<WIDTH && y>=0 && y<HEIGHT) {  // check within range
+    // return relevant bank and mask required bit
+    return (int) buffer[x][y/8] & (1 << y%8);
+    // note this does not necessarily return 1 - a non-zero number represents a pixel
+  } else {
+    return 0;
+  }
 }
 
 // function to refresh the display
 void N5110::refresh()
 {
-    int i,j;
 
-    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
+  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
 
-    sce->write(0);  //set CE low to begin frame
-
-    for(j = 0; j < BANKS; j++) {  // be careful to use correct order (j,i) for horizontal addressing
-        for(i = 0; i < WIDTH; i++) {
-            spi->write(buffer[i][j]);  // send buffer
-        }
+  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
+  }
+  sce->write(1); // set CE high to end frame
 
 }
 
@@ -236,198 +230,199 @@
 // 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
-        }
+  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 c,int x,int y)
 {
-    if (y>=0 && y<BANKS) {  // check if printing in range of y banks
+  if (y>=0 && 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
-        }
+    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
+    }
 
-        refresh();  // this sends the buffer to the display and sets address (cursor) back to 0,0
-    }
+    refresh();  // this sends the buffer to the display and sets address (cursor) back to 0,0
+  }
 }
 
 // function to print string at specified position
 void N5110::printString(const char * str,int x,int y)
 {
-    if (y>=0 && y<BANKS) {  // check if printing in range of y banks
+  if (y>=0 && 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) {
+    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];
-            }
+      // 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
+      str++;  // go to next character in string
 
-            n++;    // increment index
+      n++;    // increment index
 
-        }
+    }
 
-        refresh();  // this sends the buffer to the display and sets address (cursor) back to 0,0
-    }
+    refresh();  // this sends the buffer to the display and sets address (cursor) back to 0,0
+  }
 }
 
 // function to clear the screen
 void N5110::clear()
 {
-    clearBuffer();  // clear the buffer then call the refresh function
-    refresh();
+  clearBuffer();  // clear the buffer then call the refresh function
+  refresh();
 }
 
 // function to clear the buffer
 void N5110::clearBuffer()
 {
-    int i,j;
-    for (i=0; i<WIDTH; i++) {  // loop through the banks and set the buffer to 0
-        for (j=0; j<BANKS; j++) {
-            buffer[i][j]=0;
-        }
+  memset(buffer,0,sizeof(buffer));
+
+  /*int i,j;
+  for (i=0; i<WIDTH; i++) {  // loop through the banks and set the buffer to 0
+    for (j=0; j<BANKS; j++) {
+      buffer[i][j]=0;
     }
+  }
+  */
 }
 
 // function to plot array on display
 void N5110::plotArray(float array[])
 {
 
-    int i;
+  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));
+  }
 
-    for (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));
-    }
-
-    refresh();
+  refresh();
 
 }
 
 // function to draw circle
 void N5110:: drawCircle(int x0,int y0,int radius,int fill)
 {
-    // from http://en.wikipedia.org/wiki/Midpoint_circle_algorithm
-    int x = radius;
-    int y = 0;
-    int radiusError = 1-x;
+  // from http://en.wikipedia.org/wiki/Midpoint_circle_algorithm
+  int x = radius;
+  int y = 0;
+  int radiusError = 1-x;
 
-    while(x >= y) {
+  while(x >= y) {
 
-        // if transparent, just draw outline
-        if (fill == 0) {
-            setPixel( x + x0,  y + y0);
-            setPixel(-x + x0,  y + y0);
-            setPixel( y + x0,  x + y0);
-            setPixel(-y + x0,  x + y0);
-            setPixel(-y + x0, -x + y0);
-            setPixel( y + x0, -x + y0);
-            setPixel( x + x0, -y + y0);
-            setPixel(-x + x0, -y + y0);
-        } else {  // drawing filled circle, so draw lines between points at same y value
+    // if transparent, just draw outline
+    if (fill == 0) {
+      setPixel( x + x0,  y + y0);
+      setPixel(-x + x0,  y + y0);
+      setPixel( y + x0,  x + y0);
+      setPixel(-y + x0,  x + y0);
+      setPixel(-y + x0, -x + y0);
+      setPixel( y + x0, -x + y0);
+      setPixel( x + x0, -y + y0);
+      setPixel(-x + x0, -y + y0);
+    } else {  // drawing filled circle, so draw lines between points at same y value
 
-            int type = (fill==1) ? 1:0;  // black or white fill
+      int type = (fill==1) ? 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);
-        }
+      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;
-        }
+    y++;
+    if (radiusError<0) {
+      radiusError += 2 * y + 1;
+    } else {
+      x--;
+      radiusError += 2 * (y - x) + 1;
     }
+  }
 
 }
 
 void N5110::drawLine(int x0,int y0,int x1,int y1,int type)
 {
-    int y_range = y1-y0;  // calc range of y and x
-    int x_range = x1-x0;
-    int start,stop,step;
+  int y_range = y1-y0;  // calc range of y and x
+  int x_range = x1-x0;
+  int start,stop,step;
 
-    // if dotted line, set step to 2, else step is 1
-    step = (type==2) ? 2:1;
+  // if dotted line, set step to 2, else step is 1
+  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) ) {
+  // 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
-        start = x1>x0 ? x0:x1;
-        stop =  x1>x0 ? x1:x0;
+    // ensure we loop from smallest to largest or else for-loop won't run as expected
+    start = x1>x0 ? x0:x1;
+    stop =  x1>x0 ? x1:x0;
 
-        // loop between x pixels
-        for (int x = start; x<= stop ; x+=step) {
-            // do linear interpolation
-            int y = y0 + (y1-y0)*(x-x0)/(x1-x0);
+    // loop between x pixels
+    for (int x = start; x<= stop ; x+=step) {
+      // do linear interpolation
+      int y = y0 + (y1-y0)*(x-x0)/(x1-x0);
 
-            if (type == 0)   // if 'white' line, turn off pixel
-                clearPixel(x,y);
-            else
-                setPixel(x,y);  // else if 'black' or 'dotted' turn on pixel
-        }
-    } else {
+      if (type == 0)   // if 'white' line, turn off pixel
+      clearPixel(x,y);
+      else
+      setPixel(x,y);  // else if 'black' or 'dotted' turn on pixel
+    }
+  } else {
 
-        // ensure we loop from smallest to largest or else for-loop won't run as expected
-        start = y1>y0 ? y0:y1;
-        stop =  y1>y0 ? y1:y0;
+    // ensure we loop from smallest to largest or else for-loop won't run as expected
+    start = y1>y0 ? y0:y1;
+    stop =  y1>y0 ? y1:y0;
 
-        for (int y = start; y<= stop ; y+=step) {
-            // do linear interpolation
-            int x = x0 + (x1-x0)*(y-y0)/(y1-y0);
+    for (int y = start; y<= stop ; y+=step) {
+      // do linear interpolation
+      int x = x0 + (x1-x0)*(y-y0)/(y1-y0);
 
-            if (type == 0)   // if 'white' line, turn off pixel
-                clearPixel(x,y);
-            else
-                setPixel(x,y);  // else if 'black' or 'dotted' turn on pixel
+      if (type == 0)   // if 'white' line, turn off pixel
+      clearPixel(x,y);
+      else
+      setPixel(x,y);  // else if 'black' or 'dotted' turn on pixel
 
-        }
     }
+  }
 
 }
 
 void N5110::drawRect(int x0,int y0,int width,int height,int fill)
 {
 
-    if (fill == 0) { // transparent, just outline
-        drawLine(x0,y0,x0+width,y0,1);  // top
-        drawLine(x0,y0+height,x0+width,y0+height,1);  // bottom
-        drawLine(x0,y0,x0,y0+height,1);  // left
-        drawLine(x0+width,y0,x0+width,y0+height,1);  // right
-    } else { // filled rectangle
-        int type = (fill==1) ? 1:0;  // black or white fill
-        for (int y = y0; y<= y0+height; y++) {  // loop through rows of rectangle
-            drawLine(x0,y,x0+width,y,type);  // draw line across screen
-        }
+  if (fill == 0) { // transparent, just outline
+    drawLine(x0,y0,x0+width,y0,1);  // top
+    drawLine(x0,y0+height,x0+width,y0+height,1);  // bottom
+    drawLine(x0,y0,x0,y0+height,1);  // left
+    drawLine(x0+width,y0,x0+width,y0+height,1);  // right
+  } else { // filled rectangle
+    int type = (fill==1) ? 1:0;  // black or white fill
+    for (int y = y0; y<= y0+height; y++) {  // loop through rows of rectangle
+      drawLine(x0,y,x0+width,y,type);  // draw line across screen
     }
+  }
 
 }