LCD Display Driver

RE: LCD Display Driver

Petter Myhre — Fri, 21 Apr 2017 07:39:09 GMT

Please open a new question and link to this one if it is relevant. You should also consider adding some more information, what isn't working?

RE: LCD Display Driver

Mark — Thu, 20 Apr 2017 19:33:20 GMT

Hi phob, sorry for delayed response. I forgot my Nordic Dev Zone login info and clicked on "forgot my password", but Nordic Dev Zone hasn't been helpful at all to recover my account, so I just created another account to answer your question.

I highly recommend you use the IO port expander to free up your pins on your board, plus it is really easy to hook up one. The files I have attached here only work with TWI line, but you may be able to change it so it would suite your need.

nrf_hd44780.c

nrf_hd44780.h

main.c

Cheers, and good luck.

Mark

RE: LCD Display Driver

phob — Tue, 18 Apr 2017 01:47:16 GMT

Hi, sorry to open this tread again. I am using the library shared in this thread. But it is not working for me. I am using NRF52DK board. I dont have IO port exapander to use. Please suggest something on this.

RE: LCD Display Driver

Mark — Fri, 03 Jun 2016 17:55:43 GMT

I was afraid to damage my nRF52 board, so I managed to find another solution to work with HD44780. I'm using an IO Expander(PCF8574A) between the LCD and nRF52 board. Apparently the LCD has to be powered up with 5V input(3.3V didn't work for me), so I'm using two 2N7000 MOSFETs for voltage level shifting of TWI lines. I'm using the library provided in this link: hmario.home.xs4all.nl/.../

I managed to finally make it work, but I need to learn how to use "TWI events handler" for a more reliable coding practice, and I will create a new topic on how to do it.

RE: LCD Display Driver

Ole Bauck — Fri, 03 Jun 2016 12:02:40 GMT

Sorry I must have mixed up the datasheets, it looks like the display can be run from 3.3V. 5V on input pins is higher than spec and will make the esd protection diodes on the pins conduct, so hopefully no harm has happened.

RE: LCD Display Driver

Mark — Thu, 02 Jun 2016 01:32:46 GMT

If I hook up the LCD to 5V, that won't harm my nRF52 micro-controller, right?

RE: LCD Display Driver

Ole Bauck — Wed, 01 Jun 2016 14:36:33 GMT

Hi Mark. We do not have the resources to investigate this problem at the moment. I will ask you to try to find out the problem yourself. I noticed in the nrf_hd44780.h file that the pin definitions actually don't go up linearly from 0 to 7:

#define LCD_PIN_B4      (LCD_PIN_BASE + 5)
#define LCD_PIN_RW      (LCD_PIN_BASE + 3)

So make sure that all pins are connected correctly. The init sequence should be:

void display_init()
{
    lcd_init();
    lcd_enable_4bit_mode(false, false);
    lcd_clear_display();
    lcd_on_off_control(true, false, false);
}

RE: LCD Display Driver

Ole Bauck — Tue, 31 May 2016 15:32:02 GMT

Sorry, looks like input voltage have to be 5V

RE: LCD Display Driver

Ole Bauck — Tue, 31 May 2016 09:23:23 GMT

You should be able to use 3.3V supply for the display. I will test the code later (have to get hold of the hardware).

RE: LCD Display Driver

Mark — Tue, 24 May 2016 19:34:03 GMT

I tried the change you suggested but still doesn't work.

Do I have to power on HD44780 using 5V or can I use 3.3V? Currently I'm powering HD44780 through VSHLD(3.3V) port.

Also if you take a look at the HD44780 data sheet, on page 46, a command of 0x03 is sent three times as part of the initialization process, but I don't see that in files provided by Torbjørn Øvrebekk:

www.sparkfun.com/.../HD44780.pdf

RE: LCD Display Driver

Ole Bauck — Mon, 23 May 2016 10:35:54 GMT

Pins P0.08 to P0.11 is used for uart communication with the debug chip on nRF51 DK, so it may not work to use those pins. Try to use pins P0.12 - P0.19 instead; change the LCD_PIN_BASE to 12.

RE: LCD Display Driver

Mark — Sat, 14 May 2016 00:50:18 GMT

Hi Torbjørn,

I used the driver you provided, but I haven't been able to make it work yet. Am I supposed to use 5V or 3.3V supply voltage? I started with a blank template project, and included the path for nrf_hd44780.h and added nrf_hd44780.c to my project. My Main.c file looks like this:

#include <stdbool.h>

#include "nrf_delay.h"

#include "nrf_hd44780.h"

/**
 * @brief Function for application main entry.
 */



int main(void)
{

		//nrf_delay_us(1000000);

		lcd_init();
		
		lcd_clear_display();

		lcd_write_string("Hello", 0, false);
    while (true)
    {
        // Do nothing.
    }
}

I don't see any changes though! What am I doing wrong? ps: I'm still using P0.08-P0.15

RE: LCD Display Driver

ovrebekk — Thu, 26 Nov 2015 18:34:19 GMT

Hi Mathias

I made a simple bit-banged HD44780 driver for the nRF52 recently, but it uses only the GPIO and delay libraries and should work fine on the nRF51 as well.

The main limitation at the moment is that it assumes that all the control pins from the nRF5x will be together (ie pins P0.08-P0.15 without any unused pins in between), so you will have to make some changes to the library to get around this limitation.

nrf_hd44780.c
nrf_hd44780.h

Best regards
Torbjørn