Stap 11: Hoe teken een vierkant?
De volgende code kunt we tekenen een vierkant op onze scherm:
#include //Include Wire library for I2C communication#define HEIGHT 64 #define WIDTH 128 const int RST = 10; //Assign pin 10 for Reset int i; //Set variable i as integer static unsigned char array[1024]; //Buffer array void setup() { pin_init(); //Initialize pins initialize_OLED(); //Initialize screen memset(array, 0, sizeof(array)); //Initialize array with 0s square(117,127,53,63); //Draw square Flush(); //Send data } void loop() { } void pin_init(){ Serial.begin(9600); //Set baud for serial transmission pinMode(RST, OUTPUT); //Set RST as output } void initialize_OLED(){ Wire.begin(); //Initialize I2C interface digitalWrite(RST, LOW); //Set RST pin low delay(100); //Wait 100 ms digitalWrite(RST, HIGH); //Set RST pin high Wire.beginTransmission(0x3D); // Start communication with slave Wire.write(0x00); //Command stream Wire.write(0xAE); //Set display Off Wire.write(0xD5); //Set display clock divide ratio/oscillator frequency Wire.write(0x80); Wire.write(0xA8); //Set multiplex ratio Wire.write(0x3F); Wire.write(0xD3); //Set display offset Wire.write(0x00); Wire.write(0x40); //Set display start line Wire.write(0x8D); //Set charge pump Wire.write(0x14); //VCC generated by internal DC/DC circuit Wire.write(0xA1); //Set segment re-map Wire.write(0xC0); //Set COM output scan direction Wire.write(0xDA); //Set COM pins hardware configuration Wire.write(0x12); Wire.write(0x81); //Set contrast control Wire.write(0xCF); Wire.write(0xD9); //Set pre-changed period Wire.write(0xF1); Wire.write(0xDB); //Set VCOMH Deselected level Wire.write(0x40); Wire.write(0xA4); //Set entire display on/off Wire.write(0xA6); //Set normal/inverse display Wire.write(0x20); //Set memory address mode Wire.write(0x00); //Horizontal Wire.write(0xAF); //Set display on Wire.endTransmission(); //End communication with slave } /*Function to draw square*/ void square(int x1, int x2, int y1, int y2){ int x, y; //Define x and y as integer variables Wire.beginTransmission(0x3D); //Start communication with slave for(x=x1; x=WIDTH) || (y<0) || (y>=HEIGHT)){ //Check for boundaries return; } else{ array[x+(y/8)*WIDTH] |= _BV((y%8)); //Store pixel in array } } void Flush(){ Wire.beginTransmission(0x3D); //Start communication with slave Wire.write(0x00); //Command stream Wire.write(0x00); //Set lower column start address for page addressing mode Wire.write(0x10); //Set higher column start address for page addressing mode Wire.write(0x40); //Set display start line Wire.endTransmission(); //End communication with slave unsigned char twbrbackup = TWBR; //Two wire bit rate register TWBR = 12; //Set to 400 kHz for(unsigned short q=0; q<(WIDTH*HEIGHT/8); q++){ Wire.beginTransmission(0x3D); //Start communication with slave Wire.write(0x40); //Data stream for(unsigned char w=0; w<16; w++){ Wire.write(array[q]); //Transmit data to be displayed q++; } q--; Wire.endTransmission(); //End communication with slave } TWBR = twbrbackup; } De vierkante functie neemt vier argumenten, een begin- en eindpunt op de x- en y-as, om te bepalen van de hoogte en breedte van de rechthoek. Dan zijn vier lijnen getrokken zelfstandig gebruikt, eens te meer de functie van de pixel.
De eerste regel die moet worden getrokken is de onderste regel van onze vierkant van x1-x2 op de as y1. De tweede regel worden getrokken is de bovenste regel van onze plein van x1-x2 op de as y2. De derde lijn worden getrokken is de linkerzijde van onze vierkant van y1-y2 op de x1 as. De laatste regel worden getrokken is de rechterzijde van onze vierkant van y1-y2 op de x2 as. Zodra alle regels pixels in de array zijn opgeslagen, wordt de spoelen van de functie gebruikt om de vier regels weergegeven. Boven is het beeld van een 10 x 10 pixels vierkante gelegen op de hoogste juiste hoek van ons scherm.
