hi,
this is my first time working with a microcontroller so please bear with me. i am trying to interface a simple hd44780 type lcd to a 8051 Cygnal microcontroller. the code compiles fine and passes through the LCD functions (i am outputting data through a uart for debugging purposes). i am not getting anything out however, like the lcd doesnt even turn on. i will describe my hw and sw setup below.
HW port2's data pins are wired into d0-d7 of the lcd. port1 pins 1,2,3 are wired as the control pins of the lcd (pin1-RS, pin2-R/W, pin3-Enable). i am powering the lcd with 5V into pin 2, gnd at pin1, and 4V at pin3 (LCD contrast). i also set the latter to 0V and get a very dark contrast on each character spot, but still, nothing comes out.
SW these are the functions i call. i modeled them after a template i found on the web.
lcdInitHW(); lcdInit();
lcdDisplayChar('H'); lcdDisplayChar('e'); lcdDisplayChar('l'); lcdDisplayChar('l'); lcdDisplayChar('o');
the implementations are below
// Local low level Function Prototypes ////////////////////////////////////////// // these functions access the hardware and are dependent on hw parameters. // they also make direct use of the HD44780 instruction set
#define LCD_DATA_PORT P2 #define LCD_DATA_PORT_CONFIG P2MDOUT sbit LCD_RS = P1^0; sbit LCD_RW = P1^1; sbit LCD_E = P1^2; #define LCD_CTRL_PORT_CONFIG P1MDOUT
// 5 nops are about ~240 ns at our processor speed #define LCD_DELAY _nop_(); _nop_(); _nop_(); _nop_(); _nop_()
// configures the data port to be an input void lcdConfigDataInput(void);
// configures the data port to be an output void lcdConfigDataOutput(void);
// waits until LCD is not busy void lcdBusyWait(void);
// writes a control command to the LCD void lcdCtrlWrite(unsigned char data2write);
// writes a data byte to the LCD screen at the current position void lcdDataWrite(unsigned char data2write);
// configures pins void lcdInitHW(void);
// initializes LCD void lcdInit(void);
// Implementations //////////////////////////////////////////////////////////////
void lcdConfigDataInput(void){ // configure as input by setting to open drain and writing a one LCD_DATA_PORT_CONFIG = 0x00; LCD_DATA_PORT = 0xFF; }
void lcdConfigDataOutput(void){ // configure as output by setting to push-pull LCD_DATA_PORT_CONFIG = 0xFF; }
void lcdBusyWait(void) {
char temp;
lcdConfigDataInput();
LCD_RS = 0; LCD_RW = 1; LCD_E = 1; LCD_DELAY;
temp = LCD_DATA_PORT;
while(temp & 0x80) { LCD_E = 0; LCD_DELAY; LCD_E = 1; LCD_DELAY; temp = LCD_DATA_PORT; }
LCD_E = 0; }
void lcdCtrlWrite(unsigned char data2write) {
lcdBusyWait(); // wait until LCD not busy LCD_RS = 0; // set RS to "control" LCD_RW = 0; // set R/W to "write" LCD_E = 1; // set "E" line
lcdConfigDataOutput(); // set data I/O lines to output (8bit) LCD_DATA_PORT = data2write; // output data, 8bits LCD_DELAY; // wait LCD_E = 0; // clear "E" line
lcdConfigDataInput(); }
void lcdDataWrite(unsigned char data2write) {
lcdBusyWait(); // wait until LCD not busy LCD_RS = 1; // set RS to "control" LCD_RW = 0; // set R/W to "write" LCD_E = 1; // set "E" line
lcdConfigDataOutput(); // set data I/O lines to output (8bit) LCD_DATA_PORT = data2write; // output data, 8bits LCD_DELAY; // wait LCD_E = 0; // clear "E" line
lcdConfigDataInput();
}
void lcdInitHW(void) {
// configure the control pins to be push pull // the value depends on the pins being used, 1,2,3 in our case // have initial 4 (0x47) because I want to configure 1.6 (the LED) // as push-pull LCD_CTRL_PORT_CONFIG |= 0x47;
// initially configure data port in input mode lcdConfigDataInput(); }
void lcdInit(void) {
// LCD function set lcdCtrlWrite(0x38);
// clear LCD lcdCtrlWrite(0x01);
// set entry mode lcdCtrlWrite(0x06);
// set display to on lcdCtrlWrite(0x0F);
// move cursor to home lcdCtrlWrite(0x02);
}