my LCD shows only solid block

Hi, I am planning to allow my robot to sense temperature, then at certain temperature, the LED will light, fan work and the LCD display the temperature. I am using PIC16f877a, the pin connection between LCD and PIC looks like this,
LCD =>PIC
DB0~DB7=> RB1~RB7 (portB)
RS =>RD7
E =>RC7
However, when i try to run it, the LCD just show solid block in the first line. After troubleshoot for quite sometime, i couldn't find the root problem, can anyone help me with this? Here is my code . I look at the datasheet, it says that port B has weak pull up, do I need to disable it?

Thanks.

//==================include=================================
#include<pic.h>

//===============configuration==============================
__CONFIG (0x3F32);

//===============define IO port=============================
#define lcd PORTB //RB1-RB7
#define RS RD7
#define E RC7
#define CHANNEL0 0b10000001 // AN0
#define fanA RC1
#define ledA RC2
#define ledB RC3

//==============FUNCTION PTOTOTYPE=========================
void e_pulse(void);
void delay(unsigned short i);
void send_char(unsigned char data);
void send_config(unsigned char data);
void lcd_goto(unsigned char data);
void lcd_clr(void);
void dis_num(unsigned long data);
void increment(unsigned long data);
void read_adc(void);
unsigned short read_temp(void);

//====================MAIN================================
unsigned short result;
unsigned short temp,tempA;

void main(void)
{
ADRESH=0; //clear A/D result
ADRESL=0; //clear A/D result

//setting ADCON1 Register
ADCON1=0b11000101; // A/D result right justified,
// configure RA2 and RA5 as digital I/O

TRISA=0b11011011; //configure PORTA I/O direction
TRISB=0b00000000; //configure PORTB as output
TRISC=0b00000000; //configure PORTC as output
TRISD=0b00000000; //configure PORTD as output
TRISE=0b00000000; //set portE as output

PORTA=0;
PORTB=0;
PORTC=0;
PORTD=0;

//OPTION_REG=0b11111111;

while(1)
{
send_config(0b00000001); //clear display at lcd
send_config(0b00000010); //Lcd Return to home
send_config(0b00000110); //entry mode-cursor increase 1
send_config(0b00001100); //diplay on, cursor off and cursor blink off
send_config(0b00111000); //function set

lcd_goto(0); //cursor start from beginning

//display character on LCD
send_char(' ');
send_char('T');
send_char('E');
send_char('M');
send_char('P');
send_char('.');
send_char('=');


while(1) //infinity loop
{
//sensor A
ADCON0=CHANNEL0; //CHANNEL1=0b10001001
lcd_goto(8);

read_adc();

temp=read_temp();
dis_num(temp/10);
send_char('.');
dis_num(temp%10);
send_char(0b11011111);
send_char('C');
send_char(' ');
send_char(' ');

tempA=temp;


if(tempA>400)
{ //*LED A and Fan A activated only for
ledA=1; //*temperature A greater than 40'C
ledB=0;
fanA=1;
}

else
{
ledA=0;
ledB=1;
fanA=0;
}

delay(2000);

}

}

}



//==================subroutine LCD setting ==========================

void send_config(unsigned char data)
{
RS=0;
lcd=data;
delay(500);
e_pulse();
}

void e_pulse(void)
{
E=1;
delay(500);
E=0;
delay(500);
}

void send_char(unsigned char data)
{
RS=1;
lcd=data;
delay(500);
e_pulse();
}


void lcd_goto(unsigned char data)
{
if(data<16)
{
send_config(0x80+data);
}
else
{
data=data-20;
send_config(0xc0+data);
}
}


void lcd_clr(void)
{
RS=0;
send_config(0x01);
delay(600);
}


void dis_num(unsigned long data)
{
unsigned char hundred_thousand;
unsigned char ten_thousand;
unsigned char thousand;
unsigned char hundred;
unsigned char tenth;

hundred_thousand = data/100000;
data = data % 100000;
ten_thousand = data/10000;
data = data % 10000;
thousand = data / 1000;
data = data % 1000;
hundred = data / 100;
data = data % 100;
tenth = data / 10;
data = data % 10;

if(hundred_thousand>0)
{
send_char(hundred_thousand + 0x30); //0x30 added to become ASCII code
send_char(ten_thousand + 0x30);
send_char(thousand + 0x30);
send_char(hundred + 0x30);
send_char(tenth + 0x30);
send_char(data + 0x30);
}

else if(ten_thousand>0)
{
send_char(ten_thousand + 0x30); //0x30 added to become ASCII code
send_char(thousand + 0x30);
send_char(hundred + 0x30);
send_char(tenth + 0x30);
send_char(data + 0x30);
}
else if(thousand>0)
{
send_char(thousand + 0x30); //0x30 added to become ASCII code
send_char(hundred + 0x30);
send_char(tenth + 0x30);
send_char(data + 0x30);
}
else if(hundred>0)
{
send_char(hundred + 0x30); //0x30 added to become ASCII code
send_char(tenth + 0x30);
send_char(data + 0x30);
}
else if(tenth>0)
{
send_char(tenth + 0x30); //0x30 added to become ASCII code
send_char(data + 0x30);
}
else send_char(data + 0x30); //0x30 added to become ASCII code
}

void increment(unsigned long data)
{
unsigned short j;
for(j=10;j>0;j--)
{ lcd_goto(32);
data=data+1;
dis_num(data);
delay(10000);
}

}

//==================subroutine ADC=========================

void read_adc(void)
{
unsigned short i;
unsigned long result_temp=0;
for(i=2000;i>0;i-=1) //looping 2000 times for getting average value
{
ADGO = 1; //ADGO is the bit 2 of the ADCON0 register
while(ADGO==1); //ADC start, ADGO=0 after finish ADC progress
result=ADRESH;
result=result<<8; //shift to left for 8 bit
result=result|ADRESL; //10 bit result from ADC

result_temp+=result;
}
result = result_temp/2000; //getting average value

}

unsigned short read_temp(void)
{
unsigned short temp;
temp=result;
return temp;

}

//==================subroutine DELAY==========================
void delay(unsigned short i)
{
for(;i>0;i--);
}

charizard1987 said:

Hi, I am planning to allow my robot to sense temperature, then at certain temperature, the LED will light, fan work and the LCD display the temperature. I am using PIC16f877a, the pin connection between LCD and PIC looks like this,
LCD =>PIC
DB0~DB7=> RB1~RB7 (portB)
RS =>RD7
E =>RC7
However, when i try to run it, the LCD just show solid block in the first line...

Click to expand...

Some time ago I've been struggling with an LCD which had similar symptoms: https://www.ccsinfo.com/forum/viewtopic.php?t=30353. The problem was resolved. It turned out that the pin setting the contrast was not connected properly. So, here's a bunch of hardware troubleshooting questions:
* Could you post the part number for your LCD?
* You're writing that solid block is shown on the 1st line. Does your LCD have more than one line? If so, are other lines behaving as you expect? Do they show solid block like the 1st line?
* What does you LCD show if you power-up your device, but don't send any command from the PIC?

Hi,

Sometimes due to the wrong wiring or loose contacts, pls check

the LCD is 2x16. The solid block only shows on the first line( the upper line). I tried to modify the codes to show character on the second line; yet, it still only show solid block in the first line. I am not sure which is the part number for the LCD because behind the LCD, there are few numbers for it,
E171525 BS-6
210825670004
C216L01YBWOO
p#B0247-15:A
M#:C216-01
but I suppose the pin should be the same for any 2x16LCD?

So, these are the thing I can do,
1) errase codes in PIC and check how the LCD show. And check either the solid block only show in the first line or 2 lines. If the LCD only shows in first line, means is the LCD problem?

2) re-check the wiring.

Any other suggestion on what I need to do/check to troubleshoot it? Because I only can do it in the lab, so I plan to gather all the possible ways to troubleshoot and carry them out when I back to lab on weekdays.

But possible to have problem on the codes? Such as assign wrong address? I checked, but the codes seem alright to me.

It may not be a standard 2*16 LCD. it mayhave different pin connections. I have a long history of messing around cheep non standard/ surplus lcd,s. Until i could find a datasheet for particular lcd.