rewrote 1602 LCD interface functions to improve

RichardChambers · Jan 14, 2018 · 4d0192b · 4d0192b
1 parent 509d8ef
commit 4d0192b
Showing 1 changed file with 87 additions and 84 deletions.
diff --git a/project10/i2c_1602lcd.c b/project10/i2c_1602lcd.c
@@ -4,149 +4,152 @@
 *Author        : Alan
 *Website       : www.osoyoo.com
 *Update        : 2017/07/03
+*
+* changes and updates
+* Jan-14-2018 : R.Chambers    : rewrote functions to generalize and abstract the interfaces.
 ********************************************************************************************/
 #include <stdio.h>
+#include <string.h>
+
 #include <wiringPi.h>
 #include <wiringPiI2C.h>
-#include <string.h>
 
-int BLEN = 1;//1--open backlight.0--close backlight
-int fd;//linux file descriptor
-
-//writ a word(16 bits) to LCD
-void write_word(int data){
-    int temp = data;
-    if ( BLEN == 1 )
-        temp |= 0x08;
-    else
-        temp &= 0xF7;
-    wiringPiI2CWrite(fd, temp);
-}
+int LCDAddr = 0x27;   // I2c LCD address, use sudo i2cdetect -y 1 after hooking up 1602
+int BLEN = 1;         // 1--open backlight. 0--close backlight
+int fd;               // I2C device linux file descriptor
 
-void sendNibble (int rs, int rw, int data)
+void sendNibble (int bl, int rs, int rw, int data)
 {
     int buf = (data & 0x0F) << 4;  // data nibble in upper nibble of byte
 
     // set the command pins data in the lower nibble of byte
-    buf |= 0x04;            // EN = 1, RW = 0, RS = 0
-    buf |= (rs) ? 0x01 : 0; // set RS value
-    buf |= (rw) ? 0x02 : 0; // set RW value
-    write_word(buf);
+    buf |= (bl) ? 0x08 : 0;    // set backlight on/off value
+    buf |= 0x04;               // EN = 1, RW = 0, RS = 0
+    buf |= (rw) ? 0x02 : 0;    // set RW value
+    buf |= (rs) ? 0x01 : 0;    // set RS value
+    wiringPiI2CWrite (fd, buf);
 
-    delay(2);
+    delay (2);
 
-    buf &= 0xFB;            // Make EN = 0
-    write_word(buf);
+    buf &= 0xFB;               // Make EN = 0 to turn off latch
+    wiringPiI2CWrite (fd, buf);
 }
 
 //send command to lcd
-void send_command(int comm){
-    // Send bit7-4 firstly
-    sendNibble (0, 0, comm >> 4);
+void send_command(int comm)
+{
+    // Send upper nibble, bit 7-4 firstly
+    sendNibble (BLEN, 0, 0, comm >> 4);
 
-    // Send bit3-0 secondly
-    sendNibble (0, 0, comm);
+    // Send lower nibble, bit 3-0 secondly
+    sendNibble (BLEN, 0, 0, comm);
 }
 
-//send data to lcd
+//send data (text character) to lcd
 void send_data(int data){
-    // Send bit7-4 firstly
-    sendNibble (1, 0, data >> 4);
+    // Send upper nibble, bit 7-4 firstly
+    sendNibble (BLEN, 1, 0, data >> 4);
 
-    // Send bit3-0 secondly
-    sendNibble (1, 0, data);
-}
-
-//initialize the lcd
-void init1602 (void)
-{
-    send_command(0x33); // Must initialize to 8-line mode at first
-    delay(5);
-    send_command(0x32); // Then initialize to 4-line mode
-    delay(5);
-    send_command(0x28); // 2 Lines & 5*7 dots
-    delay(5);
-    send_command(0x0C); // Enable display without cursor
-    delay(5);
-    send_command(0x01); // Clear Screen
-    wiringPiI2CWrite(fd, 0x08);
+    // Send lower nibble, bit 3-0 secondly
+    sendNibble (BLEN, 1, 0, data);
 }
 
 //clear screen
 void clear1602(void)
 {
-    send_command(0x01); //clear Screen
+    send_command (0x01); //clear display, set cursor to home position
 }
 
 //Print the message on the lcd
-void write(int xCol, int yRow, const char data[])
+//initialize the lcd
+void init1602 (void)
+{
+    send_command (0x33); // Must initialize to 8-line mode at first
+    delay (5);
+
+    send_command (0x32); // Then initialize to 4-line mode
+    delay (5);
+
+    send_command (0x28); // 4 bit mode, 2 Lines and 5x7 pixels character size
+    delay (5);
+
+    send_command (0x0C); // Enable display without cursor
+    delay (5);
+
+    clear1602 ();
+    wiringPiI2CWrite (fd, 0x08);  // turn on backlight of LCD
+}
+
+void write (int xCol, int yRow, const char data[])
 {
-    int addr, i;
-    int tmp;
+    int len = strlen (data);
+
+    // 16 columns per row
     if (xCol < 0)  xCol = 0;
     if (xCol > 15) xCol = 15;
+
+    // only two rows or lines, row 0 and row 1
     if (yRow < 0)  yRow = 0;
     if (yRow > 1)  yRow = 1;
 
-    // Move cursor to either line 1 or line 2
-    // line 1 -> 0x80 + xCol, line 2 -> 0xC0 + xCol
-    addr = 0x80 + 0x40 * yRow + xCol;
-    send_command(addr);
+    // Move cursor to either row 0 or row 1
+    // row 0 -> 0x80 + xCol, row 1 -> 0xC0 + xCol
+    int addr = 0x80 + 0x40 * yRow + xCol;
+    send_command (addr);
 
-    tmp = strlen(data);
-    for (i = 0; i < tmp; i++){
-        send_data(data[i]);
+    int i;
+    for (i = 0; i < len; i++){
+        send_data (data[i]);
     }
 }
 
 void print_info()
 {
-    printf("\n");
-    printf("|***************************|\n");
-    printf("|    IIC 1602 LCD test      |\n");
-    printf("| --------------------------|\n");
-    printf("| | LCD |            | Pi   |\n");
-    printf("| --------------------------|\n");
-    printf("| | GND | connect to | GND  |\n");
-    printf("| | VCC | connect to | 5V   |\n");
-    printf("| | SDA | connect to | SDA.1|\n");
-    printf("| | SCL | connect to | SCL.1|\n");
-    printf("| --------------------------|\n");
-    printf("|                     OSOYOO|\n");
-    printf("|***************************|\n");
-    printf("Program is running...\n");
-    printf("Press Ctrl+C to end the program\n");
+    printf ("\n");
+    printf ("|***************************|\n");
+    printf ("|    IIC 1602 LCD test      |\n");
+    printf ("| --------------------------|\n");
+    printf ("| | LCD |            | Pi   |\n");
+    printf ("| --------------------------|\n");
+    printf ("| | GND | connect to | GND  |\n");
+    printf ("| | VCC | connect to | 5V   |\n");
+    printf ("| | SDA | connect to | SDA.1|\n");
+    printf ("| | SCL | connect to | SCL.1|\n");
+    printf ("| --------------------------|\n");
+    printf ("|                     OSOYOO|\n");
+    printf ("|***************************|\n");
+    printf ("Program is running...\n");
+    printf ("Press Ctrl+C to end the program\n");
 }
 
 int main(int argc, char *argv[])
 {
-    int LCDAddr = 0x27;//IIc LCD address
 
     //init I2C 
-    fd = wiringPiI2CSetup(LCDAddr);
+    fd = wiringPiI2CSetup (LCDAddr);
     if (fd < 0) {
         printf ("Error: I2C setup for 1602 LCD failed.\n");
         return 1;
     }
 
-    init1602();
+    init1602 ();
 
-    print_info();
+    print_info ();
 
-    write(0, 0, "Hi man.Welcome ");
-    write(0, 1, "to osoyoo.com");
-    delay(3000);
-    clear1602();
+    write (0, 0, "Hi man.Welcome ");
+    write (0, 1, "to osoyoo.com");
+    delay (3000);
+    clear1602 ();
 
     int iCount = 0;
-    while(1){
+    while (1){
 	char buf[24];
 
         iCount++;
 	sprintf (buf, "Lesson13 cnt %d", iCount);
-        write(0, 0, buf);
-        write(0, 1, "IIC LCD Test");
-        delay(2000);
+        write (0, 0, buf);
+        write (0, 1, "IIC LCD Test");
+        delay (2000);
     }
     return 0;
 }