CCS/SW-EK-TM4C1294XL: Display value in 20x4 LCD with TM4C 1294XL

Krishnat Pawar

Tool/software: Code Composer Studio

I WANT TO INTERFACE QC2004A LCD WITH TM4C 1294XL.

BELOW IS MY CODE. NO ERROR. BUT DISPLAY IS BLANK.

CONNECTION: RS-PB4, EN-PB5, D4-PE0, D5-PE1, D6-PE2, D7-PE3, VSS-GND, VDD-5V, VEE[PIN 3]-3.3V, R/W-GND, Backlight Anode-3.3V.

PLEASE SUGGEST POSSIBLE SOLUTION / POINT OUT ERRORS.

#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "driverlib/debug.h"
#include "driverlib/sysctl.h"
#include "driverlib/gpio.h"

/*
#define Function_set         0x28  //4bit_2line_5x7
#define Scroll_right         0x1E
#define Scroll_left          0x18
#define Return_Home          0x02
#define Increment_cursor     0x06
#define Decrement_cursor     0x04
#define DisplayON_CursorON   0x0E  //Display ON-OFF control
#define Blinking_cursor      0x0F
#define Invisible_cursor     0x0C
#define Blank_display        0x08
#define Clear_display        0x01
#define SetCursorto1         0x80
#define SetCursorto2         0xC0
#define SetCursorto3         0x94
#define SetCursorto4         0xD4
 */
void Initialize_LCD(void);
void string_to_lcd(unsigned char *s);
void LCD_write(unsigned char,unsigned int);


void main()
{
    SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ | SYSCTL_OSC_MAIN | SYSCTL_USE_PLL | SYSCTL_CFG_VCO_480), 120000000);
    SysCtlDelay(100000);//2ms
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);
    SysCtlDelay(100000);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
    SysCtlDelay(100000);
    GPIOPinTypeGPIOOutput(GPIO_PORTE_BASE, GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3);
    SysCtlDelay(100000);
    GPIOPinTypeGPIOOutput(GPIO_PORTB_BASE, GPIO_PIN_4|GPIO_PIN_5);
    SysCtlDelay(100000);

    GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3, 0x00);
    SysCtlDelay(2000000);//20ms
    Initialize_LCD();
    while(1){
    LCD_write(0X80,0);
    string_to_lcd("1234");
    LCD_write(0XC0,0);
    string_to_lcd("QWER");
    LCD_write(0X94,0);
    string_to_lcd("ASDF");
    LCD_write(0XD4,0);
    string_to_lcd("ZXCV");
    SysCtlDelay(0XFFFFFF00);
    }
}

void Initialize_LCD(void)
{
    GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_4, 0); //RS PIN LOW
    SysCtlDelay(5000);
    GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_5, 0); //EN PIN LOW
    SysCtlDelay(5000);

    LCD_write(0x20,0);
    SysCtlDelay(5000);
    LCD_write(0x08,0);
    SysCtlDelay(5000);
    LCD_write(0x01,0);
    SysCtlDelay(5000);
    LCD_write(0x06,0);
    SysCtlDelay(5000);
    LCD_write(0x0E,0);
    SysCtlDelay(5000);
    LCD_write(0X01,0);
    SysCtlDelay(100000);
}

void LCD_write(unsigned char data,unsigned int RS)
{
    GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_4, RS); //Cammand/Data

    SysCtlDelay(5000);
    GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_5, 1);
    SysCtlDelay(5000);
    //GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_0, ((data & 0X10)>>4));
    //GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_1, ((data & 0X20)>>5));
    //GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_2, ((data & 0X40)>>6));
    //GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_3, ((data & 0X80)>>7));
    GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_3|GPIO_PIN_2|GPIO_PIN_1|GPIO_PIN_0, ((data & 0XF0)>>4));
    SysCtlDelay(5000);
    GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_5, 0);
    SysCtlDelay(5000);

    SysCtlDelay(5000);
    GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_5, 1);
    SysCtlDelay(5000);
    //GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_0, ( data & 0X01));
    //GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_1, ((data & 0X02)>>1));
    //GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_2, ((data & 0X04)>>2));
    //GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_3, ((data & 0X08)>>3));
    GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_3|GPIO_PIN_2|GPIO_PIN_1|GPIO_PIN_0, (data & 0X0F));
    SysCtlDelay(5000);
    GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_5, 0);
    SysCtlDelay(5000);
}

void string_to_lcd(unsigned char *s)
{
    unsigned int slen;
    slen=strlen(s);
    while(slen>0)
    {
        unsigned char D=*s;
        LCD_write(*s,1);
        SysCtlDelay(0XFFFF0000);
        slen--;
        s++;
    }
}

over 8 years ago

0 cb1_mobile over 8 years ago

Guru 117855 points

Krishnat Pawar said:
PLEASE SUGGEST POSSIBLE SOLUTION / POINT OUT ERRORS.

That's quite a task listing - is it not?

You do (neither) yourself - nor your helpers - any favor by electing, "4 Bit LCD Mode." The "saving" of 4 GPIO is achieved at much greater SW complexity - and loss of display "robustness!" (as ANY glitch upon "E" will throw the Lcd into complete disorder! ... i.e. the dual, "nibble" transfer sequence will be "unpaired.")

Your understanding of this vendor's most helpful API demands further review (especially GPIO Reads/Writes). Here's (just one) example:

Krishnat Pawar said:
GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_5, 1);

While the use of "1" to "Set a Bit" is usual - it FAILS here! Your review of the SW-DRL-User Guide reveals that the "3rd parameter must be the "bit-packed/valued" of the targeted bit." (which is NOT "1" - instead GPIO_PIN_5 has the bit-packed value of 32. Likewise "PIN_7 is 128, PIN_4 is 16, PIN_0 IS 1.)

There are bound to be even further code errors - yet your "retreat from the needless complexity demanded by "Four Bit LCD Mode" is paramount!

Your search of this forum will reveal my (multiple) past postings - some of which included the "Grandfather LCD Control IC's spec" - which revealed the complex Initialization Code and Timing. Getting that (at all wrong) DOOMS all subsequent effort.

You note the Lcd's contrast pin as set to 3V3 - while possible - it is far more usual that the contrast pin is adjusted near GND - check your display's data sheet for the specifics.

Four Bit LCD Mode is (most properly) reserved for high volume Apps - and cannot justify the extra "time/attention" demanded - so that 4 GPIO are saved... (for a limited volume usage...)

0 Charles Tsai over 8 years ago

TI__Guru**** 184486 points

Hi Krishnat ,

I think the best is for you to check on the logic analyzer if all the signals are properly generated to the LCD with respect to the timing requirements demanded by your LCD display. Check if the LCD has proper power supply and if you are manipulating the signals correctly. Below is a reference for how someone has done it in Raspberry Pi.

https://www.raspberrypi-spy.co.uk/2012/08/20x4-lcd-module-control-using-python/

LCD Pin	Function	Pi Function	Pi Pin
01	GND	GND	P1-06
02	+5V	+5V	P1-02
03	Contrast
04	RS	GPIO7	P1-26
05	RW	GND	P1-06
06	E	GPIO8	P1-24
07	Data 0
08	Data 1
09	Data 2
10	Data 3
11	Data 4	GPIO25	P1-22
12	Data 5	GPIO24	P1-18
13	Data 6	GPIO23	P1-16
14	Data 7	GPIO18	P1-12
15	+5V via 560 ohm
16	GND		P1-06

#!/usr/bin/python
#--------------------------------------
#    ___  ___  _ ____
#   / _ \/ _ \(_) __/__  __ __
#  / , _/ ___/ /\ \/ _ \/ // /
# /_/|_/_/  /_/___/ .__/\_, /
#                /_/   /___/
#
#  lcd_16x2.py
#  20x4 LCD Test Script with
#  backlight control and text justification
#
# Author : Matt Hawkins
# Date   : 06/04/2015
#
# www.raspberrypi-spy.co.uk/
#
#--------------------------------------
 
# The wiring for the LCD is as follows:
# 1 : GND
# 2 : 5V
# 3 : Contrast (0-5V)*
# 4 : RS (Register Select)
# 5 : R/W (Read Write)       - GROUND THIS PIN
# 6 : Enable or Strobe
# 7 : Data Bit 0             - NOT USED
# 8 : Data Bit 1             - NOT USED
# 9 : Data Bit 2             - NOT USED
# 10: Data Bit 3             - NOT USED
# 11: Data Bit 4
# 12: Data Bit 5
# 13: Data Bit 6
# 14: Data Bit 7
# 15: LCD Backlight +5V**
# 16: LCD Backlight GND
 
#import
import RPi.GPIO as GPIO
import time
 
# Define GPIO to LCD mapping
LCD_RS = 7
LCD_E  = 8
LCD_D4 = 25
LCD_D5 = 24
LCD_D6 = 23
LCD_D7 = 18
LED_ON = 15
 
# Define some device constants
LCD_WIDTH = 20    # Maximum characters per line
LCD_CHR = True
LCD_CMD = False
 
LCD_LINE_1 = 0x80 # LCD RAM address for the 1st line
LCD_LINE_2 = 0xC0 # LCD RAM address for the 2nd line
LCD_LINE_3 = 0x94 # LCD RAM address for the 3rd line
LCD_LINE_4 = 0xD4 # LCD RAM address for the 4th line
 
# Timing constants
E_PULSE = 0.0005
E_DELAY = 0.0005
 
def main():
  # Main program block
 
  GPIO.setmode(GPIO.BCM)       # Use BCM GPIO numbers
  GPIO.setup(LCD_E, GPIO.OUT)  # E
  GPIO.setup(LCD_RS, GPIO.OUT) # RS
  GPIO.setup(LCD_D4, GPIO.OUT) # DB4
  GPIO.setup(LCD_D5, GPIO.OUT) # DB5
  GPIO.setup(LCD_D6, GPIO.OUT) # DB6
  GPIO.setup(LCD_D7, GPIO.OUT) # DB7
  GPIO.setup(LED_ON, GPIO.OUT) # Backlight enable
 
  # Initialise display
  lcd_init()
 
  # Toggle backlight on-off-on
  lcd_backlight(True)
  time.sleep(0.5)
  lcd_backlight(False)
  time.sleep(0.5)
  lcd_backlight(True)
  time.sleep(0.5)
 
  while True:
 
    # Send some centred test
    lcd_string("--------------------",LCD_LINE_1,2)
    lcd_string("Rasbperry Pi",LCD_LINE_2,2)
    lcd_string("Model B",LCD_LINE_3,2)
    lcd_string("--------------------",LCD_LINE_4,2)
 
    time.sleep(3) # 3 second delay
 
    lcd_string("Raspberrypi-spy",LCD_LINE_1,3)
    lcd_string(".co.uk",LCD_LINE_2,3)
    lcd_string("",LCD_LINE_3,2)
    lcd_string("20x4 LCD Module Test",LCD_LINE_4,2)
 
    time.sleep(3) # 20 second delay
 
    # Blank display
    lcd_byte(0x01, LCD_CMD)
 
    time.sleep(3) # 3 second delay
 
def lcd_init():
  # Initialise display
  lcd_byte(0x33,LCD_CMD) # 110011 Initialise
  lcd_byte(0x32,LCD_CMD) # 110010 Initialise
  lcd_byte(0x06,LCD_CMD) # 000110 Cursor move direction
  lcd_byte(0x0C,LCD_CMD) # 001100 Display On,Cursor Off, Blink Off
  lcd_byte(0x28,LCD_CMD) # 101000 Data length, number of lines, font size
  lcd_byte(0x01,LCD_CMD) # 000001 Clear display
  time.sleep(E_DELAY)
 
def lcd_byte(bits, mode):
  # Send byte to data pins
  # bits = data
  # mode = True  for character
  #        False for command
 
  GPIO.output(LCD_RS, mode) # RS
 
  # High bits
  GPIO.output(LCD_D4, False)
  GPIO.output(LCD_D5, False)
  GPIO.output(LCD_D6, False)
  GPIO.output(LCD_D7, False)
  if bits&0x10==0x10:
    GPIO.output(LCD_D4, True)
  if bits&0x20==0x20:
    GPIO.output(LCD_D5, True)
  if bits&0x40==0x40:
    GPIO.output(LCD_D6, True)
  if bits&0x80==0x80:
    GPIO.output(LCD_D7, True)
 
  # Toggle 'Enable' pin
  lcd_toggle_enable()
 
  # Low bits
  GPIO.output(LCD_D4, False)
  GPIO.output(LCD_D5, False)
  GPIO.output(LCD_D6, False)
  GPIO.output(LCD_D7, False)
  if bits&0x01==0x01:
    GPIO.output(LCD_D4, True)
  if bits&0x02==0x02:
    GPIO.output(LCD_D5, True)
  if bits&0x04==0x04:
    GPIO.output(LCD_D6, True)
  if bits&0x08==0x08:
    GPIO.output(LCD_D7, True)
 
  # Toggle 'Enable' pin
  lcd_toggle_enable()
 
def lcd_toggle_enable():
  # Toggle enable
  time.sleep(E_DELAY)
  GPIO.output(LCD_E, True)
  time.sleep(E_PULSE)
  GPIO.output(LCD_E, False)
  time.sleep(E_DELAY)
 
def lcd_string(message,line,style):
  # Send string to display
  # style=1 Left justified
  # style=2 Centred
  # style=3 Right justified
 
  if style==1:
    message = message.ljust(LCD_WIDTH," ")
  elif style==2:
    message = message.center(LCD_WIDTH," ")
  elif style==3:
    message = message.rjust(LCD_WIDTH," ")
 
  lcd_byte(line, LCD_CMD)
 
  for i in range(LCD_WIDTH):
    lcd_byte(ord(message[i]),LCD_CHR)
 
def lcd_backlight(flag):
  # Toggle backlight on-off-on
  GPIO.output(LED_ON, flag)
 
if __name__ == '__main__':
 
  try:
    main()
  except KeyboardInterrupt:
    pass
  finally:
    lcd_byte(0x01, LCD_CMD)
    lcd_string("Goodbye!",LCD_LINE_1,2)
    GPIO.cleanup()

0 cb1_mobile over 8 years ago in reply to Charles Tsai

Guru 117855 points

Hi Charles,

Looking at this (Rasp) fellow's "LCD Init" - I do not believe it to be correct. Improper initialization - as stated - DOOMS all subsequent efforts.
In addition - the "critical" contrast pin's level (Pin 3) - has been "unspecified!" Attention to such detail IS required... (throws all that follows under suspicion...)

The "lack of robustness" via 4-Bit Mode is little recognized - yet VERY REAL - and is employed in your presented example. As you know - a clear Violation of KISS! "Saving 4 GPIO - at risk of a highly disordered display screen" - proves an unsatisfactory, "Risk vs. Reward."

0 Charles Tsai over 8 years ago in reply to cb1_mobile

TI__Guru**** 184486 points

Hi cb1,
Thanks for catching the offending code line (appearing in multiple places using GPIOPinWrite) and the recommendation.

0 cb1_mobile over 8 years ago in reply to Charles Tsai

Guru 117855 points

Hi Charles,

It is my belief that such "offending code lines" occur w/in, "O.P.'s code" AS WELL as "Rasp's code!" (and do note that Rasp "ducked" the (necessary voltage level setting of display's (critical) Contrast pin!)

Not all code - found "free" on the net - is insured to "function as desired..."

You (must) have noted that (both) o.p. and "Rasp" have chosen the far more demanding, more complex, "Four Bit LCD Mode!" By your presentation of the "Rasp" code (which I believe incorrect) is it your opinion that "Code Ease & Robustness" should be TRADED for the "saving of 4 GPIO?"

Such is NEVER my recommendation... KISS - even though banned here - especially as banned here - truly RULES!

0 Krishnat Pawar over 8 years ago in reply to cb1_mobile

Intellectual 580 points

HI,

THANK YOU FOR SUPPORT.

CONNECTION: VSS[PIN-1]-GND, VDD[PIN-1]-5V, VEE[PIN 3]-VARIABLE POT, RS[PIN 4]-PB4, R/W[PIN 5]-GND, EN[PIN 6]-PB5, DB0-DB3- N.C. D4-PE0, D5-PE1, D6-PE2, D7-PE3, A[PIN 15]-VARIABLE POT, A[PIN 16]-GND

#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "driverlib/debug.h"
#include "driverlib/sysctl.h"
#include "driverlib/gpio.h"


void Initialize_LCD(void);
void string_to_lcd(unsigned char *s);
void LCD_write(unsigned char,unsigned int);


void main()
{
SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ | SYSCTL_OSC_MAIN | SYSCTL_USE_PLL | SYSCTL_CFG_VCO_480), 120000000);
SysCtlDelay(100000);//2ms
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);
SysCtlDelay(100000);
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
SysCtlDelay(100000);
GPIOPinTypeGPIOOutput(GPIO_PORTE_BASE, GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3);
SysCtlDelay(100000);
GPIOPinTypeGPIOOutput(GPIO_PORTB_BASE, GPIO_PIN_4|GPIO_PIN_5);
SysCtlDelay(100000);

GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3, 0x00);
SysCtlDelay(2000000);//20ms
Initialize_LCD();



LCD_write(0X80,0);
string_to_lcd("Hello");
LCD_write(0XC0,0);
string_to_lcd("TI E2E COMMUNITY");
LCD_write(0X94,0);
string_to_lcd("HI cb1 & Charles");
LCD_write(0XD4,0);
string_to_lcd("THANK YOU !!");
SysCtlDelay(0XFFFFFF00);

while(1){
}
}

void Initialize_LCD(void)
{
GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_4, 0xEF); //RS PIN LOW
SysCtlDelay(5000);
GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_5, 0xDF); //EN PIN LOW
SysCtlDelay(5000);

LCD_write(0x33,0);
SysCtlDelay(5000);
LCD_write(0x32,0);
SysCtlDelay(5000);
LCD_write(0x06,0);
SysCtlDelay(5000);
LCD_write(0x0E,0);
SysCtlDelay(5000);
LCD_write(0x28,0);
SysCtlDelay(5000);
LCD_write(0X01,0);
SysCtlDelay(10000000);
}

void LCD_write(unsigned char data,unsigned int RS)
{
if(RS==0)
GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_4, 0xEF); //Cammand
else
GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_4, 0xFF); //Data

SysCtlDelay(5000);
GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_5, 0xFF);
SysCtlDelay(5000);

GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_3|GPIO_PIN_2|GPIO_PIN_1|GPIO_PIN_0, ((data & 0XF0)>>4));
SysCtlDelay(5000);
GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_5, 0xDF);
SysCtlDelay(5000);

SysCtlDelay(5000);
GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_5, 0xFF);
SysCtlDelay(5000);

GPIOPinWrite(GPIO_PORTE_BASE, GPIO_PIN_3|GPIO_PIN_2|GPIO_PIN_1|GPIO_PIN_0, (data & 0X0F));
SysCtlDelay(5000);
GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_5, 0xDF);
SysCtlDelay(5000);
}

void string_to_lcd(unsigned char *s)
{
unsigned int slen;
slen=strlen(s);
while(slen>0)
{
unsigned char D=*s;
LCD_write(*s,1);
SysCtlDelay(1000000);
slen--;
s++;
}

}

0 Bruno Saraiva over 8 years ago in reply to Krishnat Pawar

Guru 13040 points

**** LIKE!!!!! *****

That is one highly creative Thank You message!!!!

0 Charles Tsai over 8 years ago in reply to Krishnat Pawar

TI__Guru**** 184486 points

Glad your problem is solved.

0 cb1_mobile over 8 years ago in reply to Krishnat Pawar

Guru 117855 points

So INSPIRED a POST demands a "Double LIKE!" (for execution - especially your photo!) (I actually thought, "How great it would be if poster "showed his screen" (as I read your display message) and then saw that you, "Did just that!"

*** LIKE ***

That said - having been (very) successful in the display biz - ALL EIGHT DATA Bits (wiring) reveal w/in your great photo! (law-school "evidence training")

(I remain uncertain (even doubtful) over the correctness of your 4 bit initialization - although you did modify it between first & second postings.)

The fact that "ANY glitch upon "E" will "Throw your display into disorder" - as "DIRECT CONSEQUENCE OF 4 BIT MODE" - introduces an element of risk! (not properly "rewarded" via the saving of 4 GPIO!)

In addition the "write (or read) time" for each/every character is DOUBLED!

So rare that "helpers" are rewarded - great kindness on your part - and IMAGINATIVELY DELIVERED! (Switching to (proper) 8 bit mode adds ROBUSTNESS to your effort...)

Arm-based microcontrollers

Arm-based microcontrollers forum

CCS/SW-EK-TM4C1294XL: Display value in 20x4 LCD with TM4C 1294XL

https://www.raspberrypi-spy.co.uk/2012/08/20x4-lcd-module-control-using-python/