UDOO NEO with Liquid Crystal Display

realny10 · Jan 14, 2016

Hi!

I've already bought the UDOO NEO Full.

I need to make a device, which allows me to control 4 relays. I also want to include LCD and GSM Module.

At the beginning I thought about C programming. Now I see that at UDOO I have to use Linux comands, even if writing in C. I think that it will be very difficult to use that method to program LCD or GSM module.

So I decided to use Arduino. It's much easier in use and has many libraries.
However, when I uploaded an example program with Crystal Liquid, which is originally saved at UDOO, it didn't work. I checked it with Arduino UNO and everything was ok. UDOO works well with relays or LEDs.

Did someone have the same problem as me and knows what can I do with that?
Or maybe programming LCD and GSM module in C isn't as difficult as I think?

Andrea Rovai · Jan 14, 2016

Hi realny10,
what do you mean by

Now I see that at UDOO I have to use Linux comands, even if writing in C. I think that it will be very difficult to use that method to program LCD or GSM module.
Click to expand...

?
Concerning the library, we have to refine it, it's not compatible at date.

realny10 · Jan 14, 2016

I mean that, to use LCD, I have to use similar library to that :

fetcher said: ↑

Here is some C code I wrote for sending text to an HD44780 on the Udoo, which might be useful as a template for yours. Note the particular pins I used, which you'll probably want to change... I picked GPIO's all on a single row of the double-wide header (with GND and +5V at either end) while trying to avoid the ones also usable for SPI buses, UARTs etc. so that those remained free for future expansion.

These displays seem happy to accept 3.3V signals (they do need +5V for power and contrast bias), just be sure R/W is pulled low, tied to ground, so that the LCD never tries to send any data back at 5V levels.

Code:

// jnh - based on Adafruit Adafruit_CharLCD_IPclock_example.py
// 2014-07-07

#include <stdio.h>
#include <stdlib.h>
#include <error.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

// commands
#define LCD_CLEARDISPLAY             0x01
#define LCD_RETURNHOME               0x02
#define LCD_ENTRYMODESET             0x04
#define LCD_DISPLAYCONTROL           0x08
#define LCD_CURSORSHIFT              0x10
#define LCD_FUNCTIONSET              0x20
#define LCD_SETCGRAMADDR             0x40
#define LCD_SETDDRAMADDR             0x80

// flags for display entry mode ( | LCD_ENTRYMODESET = 0x04 );
#define LCD_ENTRYRIGHT               0x00
#define LCD_ENTRYLEFT                0x02
#define LCD_ENTRYSHIFTINCREMENT      0x01
#define LCD_ENTRYSHIFTDECREMENT      0x00

// flags for display on/off control ( | DISPLAYCONTROL = 0x08 )
#define LCD_DISPLAYON                0x04
#define LCD_DISPLAYOFF               0x00
#define LCD_CURSORON                 0x02
#define LCD_CURSOROFF                0x00
#define LCD_BLINKON                  0x01
#define LCD_BLINKOFF                 0x00

// flags for display/cursor shift  ( | LCD_CURSORSHIFT = 0x10 )
#define LCD_DISPLAYMOVE              0x08
#define LCD_CURSORMOVE               0x00
#define LCD_MOVERIGHT                0x04
#define LCD_MOVELEFT                 0x00

// flags for function set    ( | LCD_FUNCTIONSET = 0x20 )
#define LCD_8BITMODE                 0x10
#define LCD_4BITMODE                 0x00
#define LCD_2LINE                    0x08
#define LCD_1LINE                    0x00
#define LCD_5x10DOTS                 0x04
#define LCD_5x8DOTS                  0x00

int RS, EN, D[8];
unsigned char displaycontrol=0, displayfunction=0, displaymode=0;

pulse_en () {
        write(EN, "1",1);
        usleep(2);
        write(EN, "0",1);
        usleep(1);
        write(EN, "1",1);
        usleep(2);
}

write1nibble(unsigned char nib) {
        write(RS, "0", 1);

        write(D[7], (nib & 0x8) ? "1" : "0", 1);
        write(D[6], (nib & 0x4) ? "1" : "0", 1);
        write(D[5], (nib & 0x2) ? "1" : "0", 1);
        write(D[4], (nib & 0x1) ? "1" : "0", 1);
        usleep(20);

        pulse_en();

        usleep(40);
}

writenibbles(unsigned char value, char mode) {
        unsigned char nib;

        //fprintf(stderr,"sending %X / %d]\n",value, mode);

        write(RS, mode ? "1" : "0", 1);

        /* high nibble first */
        nib = (value >> 4);

        write(D[7], (nib & 0x8) ? "1" : "0", 1);
        write(D[6], (nib & 0x4) ? "1" : "0", 1);
        write(D[5], (nib & 0x2) ? "1" : "0", 1);
        write(D[4], (nib & 0x1) ? "1" : "0", 1);
        usleep(20);

        pulse_en();

        usleep(20);

        nib = (value & 0x0f);

        write(D[7], (nib & 0x8) ? "1" : "0", 1);
        write(D[6], (nib & 0x4) ? "1" : "0", 1);
        write(D[5], (nib & 0x2) ? "1" : "0", 1);
        write(D[4], (nib & 0x1) ? "1" : "0", 1);
        usleep(20);

        pulse_en();

        usleep(100);
}

message (char *msg) {
int j;

for (j=0; (msg[j]!=0); j++) {
  if ((msg[j] == '\n' || msg[j] == '\r'))
        writenibbles(0xC0,0);  /* next line */
   else writenibbles(msg[j],1);
}

}

main(int argc, char **argv) {

int DIR;

int i,s,gpio[] = { 33, 35, 205, 141, 139, 135 };
unsigned char tmp[256];

/*
  D7: 29 / gpio135
  D6: 33 / gpio139 (ECSPI2_MISO, mirrored on 50)
  D5: 35 / gpio141 (ECSPI2_SCLK, mirroed on 52)
  D4: 39 / gpio205
  EN: 41 / gpio35
  RS: 43 / gpio33
*/

for (i=0; i<6; i++) {
  sprintf(tmp, "/sys/class/gpio/gpio%d/direction",gpio[i]);
  if  ( ( DIR=open(tmp,O_WRONLY|O_SYNC) ) <= 0 ) { fprintf(stderr,"%s\n",tmp); perror("gpio_dir_setup"); exit(1); }
  write(DIR,"out\n",4);
  close(DIR);
}
sprintf(tmp, "/sys/class/gpio/gpio%d/value",gpio[0]);
if  ( ( RS=open(tmp,O_WRONLY|O_SYNC) ) <= 0 ) { perror("gpio0_val"); exit(1); }
write(RS, "0",1);
sprintf(tmp, "/sys/class/gpio/gpio%d/value",gpio[1]);
if  ( ( EN=open(tmp,O_WRONLY|O_SYNC) ) <= 0 ) { perror("gpio1_val"); exit(1); }
write(EN, "1",1);
sprintf(tmp, "/sys/class/gpio/gpio%d/value",gpio[2]);
if  ( ( D[4]=open(tmp,O_WRONLY|O_SYNC) ) <= 0 ) { perror("gpio2_val"); exit(1); }
write(D[4], "0",1);
sprintf(tmp, "/sys/class/gpio/gpio%d/value",gpio[3]);
if  ( ( D[5]=open(tmp,O_WRONLY|O_SYNC) ) <= 0 ) { perror("gpio3_val"); exit(1); }
write(D[5], "0",1);
sprintf(tmp, "/sys/class/gpio/gpio%d/value",gpio[4]);
if  ( ( D[6]=open(tmp,O_WRONLY|O_SYNC) ) <= 0 ) { perror("gpio4_val"); exit(1); }
write(D[6], "0",1);
sprintf(tmp, "/sys/class/gpio/gpio%d/value",gpio[5]);
if  ( ( D[7]=open(tmp,O_WRONLY|O_SYNC) ) <= 0 ) { perror("gpio5_val"); exit(1); }
write(D[7], "0",1);

/* init: enter & exit 8-bit mode to reset possible nibble misalignment... */
write1nibble(0x3);
usleep(5000);
write1nibble(0x3);
usleep(5000);
write1nibble(0x3);
usleep(1000);
write1nibble(0x2);
usleep(1000);

writenibbles(LCD_FUNCTIONSET | LCD_4BITMODE | LCD_2LINE | LCD_5x8DOTS,0);
usleep(50);
writenibbles(LCD_DISPLAYCONTROL | LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF,0);  // 0x0C
usleep(50);
writenibbles(LCD_ENTRYMODESET | LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT,0);         // 0x06
usleep(50);

writenibbles(LCD_CLEARDISPLAY,0);
usleep(3200);

if (argc > 2) {
   s=atoi(argv[1]);
   for (i=s;i<(s+16);i++) writenibbles(i,1);
   writenibbles(0xC0,0);
   for (i=(s+16);i<(s+32);i++) writenibbles(i,1);
}
else if (argc != 1 )
  message (argv[1]);

for (i=4; i<8; i++) {
  close(D[i]);
}
close(EN); close(RS);
}

Click to expand...

So, sth like that is needed to control GPIO:
sprintf(tmp, "/sys/class/gpio/gpio%d/value",gpio[0]);

It's a big disappointment for me to hear, that some libraries of Arduino can be uncompatible with UDOO.
When can the library for Liquid Crystal be completed and ready to use?

Andrea Rovai · Jan 14, 2016

Dear realny10,
I can ensure you we're working on this matter to port the most requested Arduino libraries on UDOO NEO.

realny10 · Jan 14, 2016

Fine, thanks.

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UDOO NEO with Liquid Crystal Display

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