Interfacing a 16x2 LCD with SPI, Getting Characters into the Second Row - c

Question

I'm using an MSP430 MCU to read analog signals and display the results on an LCD with a SPI connection. The LCD is a 16x2 that is connected according to the SPI connection details on the Datasheet and uses a Hitachi HD44780 driver. I can fill up the 16 characters of the first row no problem. When I go over 16, the last character does not display(as expected) even if I extend the char array that holds the string that I want to print. The problem is that the second row never displays anything. When there are no characters in a position in the first row, there is still a faint background in all positions, but the second row is always continuously blank. Below are the functions that are used in printing. What am I doing wrong?
I know the wiring is correct and the LCD is functional. To test these, I wired the display to an arduino to test, since the code is much easier and I was able to display characters in bow rows. The non-descriptive variables are defined by the MSP430 source files and include registers, buffers, and other controls to put the device in SPI communication mode.
void AlignLaserTarget()
{
int i,k, j;
struct testResults *ptestResults;
char mess1[17]; //changed from 8 to hold 16 characters
ptestResults=getTestResults();
// reset global vars
timeI1=0;
timeA=0;
i=starResults.ch1Amplitude; //analog integer value to be printed on LCD
j=starResults.ch2Amplitude; //same
k=starResults.ch3Amplitude; //same, but should go in second row
sprintf(mess1,"1:%i 2:%i", i, j);
stringTo_lcd8( mess1);
}
void stringTo_lcd8( char* lcdString )
{
int i;
LCD_COMMAND_MODE; // display code
timer_us(20);
write_lcd8( 0x01); // clear display
timer_ms(2);
LCD_DATA_MODE; //enable data sending pin
for ( i=0; *lcdString !=0 ; ++i)
{
write_lcd8( *lcdString);
++lcdString;
} // end of display code
timer_us(10000); // 10ms delay . should not be needed as normal interval between counts is at least 75 ms or 12 in. at 800ft/min rate
}
//*******************************************************
void write_lcd8( unsigned char lcdbyte)
{
UCA0IFG &= ~UCTXIFG; // CLEAR FLAG
UCA0CTL1 |= UCSWRST; // **Put state machine in reset**
UCA0CTL0 = UCMST+UCSYNC+ UCMSB+ UCCKPH;
UCA0BR0 = 0x80; // /hex80
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
timer_us(100);
LCD_CHIP_ENABLE; // LCD enable pin output
timer_us(20); // added trp
UCA0TXBUF =lcdbyte;
timer_us(150);
while (!(UCA0IFG&UCTXIFG));
UCA0IFG &= ~UCTXIFG; // CLEAR FLAG
LCD_CHIP_DISABLE;
timer_us(30);
UCA0CTL1 |= UCSWRST; // **Put state machine in reset**
UCA0CTL0 |= UCMST+UCSYNC+ UCMSB+ UCCKPH;
UCA0BR0 = 0x02; // /2
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
}

Answer 1

I think you have to design some more driver function before using for application logic. I have taken sample code to set cursor position
void Lcd8_Set_Cursor(char line, char col)
{
if(line == 1)
Lcd8_Cmd(0x80 + col);
else if(line == 2)
Lcd8_Cmd(0xC0 + col);
}
Then use same in your printing logic. When ever length exceeding 16 you can switch line and start writing.

Answer 2

The HD44780 is expecting 40 characters per row, so I just added spaces to fill up the first row and then wrote the characters for the next row. I'm sure there is a better solution but this was fast and it worked. I also had to change the initialization specifications for a two row configuration.