Diff: N5110.cpp

Revision:

6:adb79338d40f

Parent:

5:6ea180eef702

Child:

7:77bd2c73fe41

diff -r 6ea180eef702 -r adb79338d40f N5110.cpp
--- a/N5110.cpp	Sun Jan 26 20:18:45 2014 +0000
+++ b/N5110.cpp	Mon Jan 27 18:41:45 2014 +0000
@@ -14,6 +14,7 @@
     spi = new SPI(mosiPin,NC,sclkPin); // create new SPI instance and initialise
     initSPI();    
     
+    // set up pins as required
     led = new PwmOut(ledPin);
     pwr = new DigitalOut(pwrPin);
     sce = new DigitalOut(scePin);
@@ -22,15 +23,17 @@
 
 }
 
-
+// initialise function - powers up and sends the initialisation commands
 void N5110::init()
 {
-    turnOn();    // power up
-    reset();     // reset LCD - must be done within 100 ms
+    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
 
     // 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
@@ -39,7 +42,6 @@
     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
-    //sendCommand(CMD_DC_INVERT_VIDEO);  // white on black
 
     // RAM is undefined at power-up so clear
     clearRAM();
@@ -68,12 +70,16 @@
 // 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 model
     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);
     pwr->write(0);
 
 }
@@ -105,6 +111,7 @@
     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
@@ -115,6 +122,9 @@
 
 }
 
+// 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
@@ -134,9 +144,9 @@
 
 }
 
+// function to set the XY address in RAM for subsequenct data write 
 void N5110::setXYAddress(int x, int y)
 {
-
     // check whether address is in range
     if (x > 83)
         x=83;
@@ -151,9 +161,12 @@
     sendCommand(0x40 | 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(int x, int y)
 {
-    // calculate bank and shift 1 to required position
+    // calculate bank and shift 1 to required position in the data byte
     buffer[x][y/8] |= (1 << y%8);
 }
 
@@ -170,9 +183,9 @@
 
 }
 
-void N5110::refreshDisplay()
+// function to refresh the display
+void N5110::refresh()
 {
-
     int i,j;
     sce->write(0);  //set CE low to begin frame
 
@@ -185,11 +198,11 @@
 
 }
 
+// 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 < 6; j++) {  // be careful to use correct order (j,i) for horizontal addressing
         for(i = 0; i < 84; i++) {
             buffer[i][j] = rand()%256;  // generate random byte
@@ -201,13 +214,13 @@
 // function to print 5x7 font
 void N5110::printChar(char c)
 {
-
+    int i;
     // loop through 5 columns
-    for (int j = 0; j < 5 ; j++ ) {
-        sendData(font5x7[(c - 32)*5 + j]);
+    for (i = 0; i < 5 ; i++ ) {
+        sendData(font5x7[(c - 32)*5 + i]);
         // array is offset by 32 relative to ASCII, each character is 5 pixels wide
+        // the X address is automatically incremented after each data write
     }
-    
     sendData(0); // send an empty byte to introduce space between characters
 
 }
@@ -220,23 +233,25 @@
     while(*str) {
 
         setXYAddress(x+6*n,y);  // leave 1 pixel (6 = 5 + 1) between each character
-        printChar(*str);
+        printChar(*str);   // print the char - can probably so *str++ and remove next line
         str++;  // go to next character in string
         n++;    // increment index
     }
 
 }
 
+// function to clear the screen
 void N5110::clear()
 {
-    clearBuffer();
-    refreshDisplay();
+    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<84; i++) {
+    for (i=0; i<84; i++) {  // loop through the banks and set the buffer to 0
         for (j=0; j<6; j++) {
             buffer[i][j]=0;
         }