LeafLabs Garden

A place to share, learn, and grow...

1. 

   JCNZL
   Member

   Hi Guys
   Wondering if anyone has any idea what could be causing this problem.

   I have a Character LCD Screen ( 16x2 ) that is running off a maple mini.
   It works fine, for an unspecified ammount of time. ( sometimes 10 mins, sometimes 2 mins, and sometimes an hour )

   When the error occurs, all the characters go crazy. They display some letters, some numbers, some random shapes. Some ascii symbols etc.

   If i press the reset button, the LCD returns working perfectly fine ( until the next glitch )

   I have tried this with a few different sketches, including the one below

   #include <LiquidCrystal.h>

   LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

   void setup() {

   lcd.begin(16, 2);

   lcd.print("Hello, Mars!");
   }

   void loop() {

   lcd.setCursor(0, 1);
   lcd.print(millis()/1000);
   }

   Notes:
   The LCD and this code work fine running off an Arduino
   I have tried this code on 2 different Maple Minis - both produce the same error.

   I really want to be able to use the maple mini for my project, but at the moment, this is a bit of a deal breaker :(

   Any help would be greatly appreciated

   Posted 2 years ago #
2. 

   gbulmer
   Moderator

   JCNZL - That sounds like there may be a problem with the communication between the mini and the LCD.

   Would you please give us some more information?

   Is this the original Arduino code, or a port of that code to Maple?
   Remember that the mini is significantly faster than an Arduino, and so the LCD may be able to keep up with the Arduino, but not the mini.

   What is the part number of the LCD?
   What is the communication mechanism between the Maple and the LCD? Is it a UART, SPI, ...?

   Have you tried putting a small delay into loop, e.g.:
   

   void loop() {
   
       lcd.setCursor(0, 1);
       delayMicroseconds(100);
       lcd.print(millis()/1000);
       delayMicroseconds(100);
   }

   This might give enough time for the LCD to do its stuff.

   It is possible that there is a bug in 'print', and slowing it down changes the effect.
   Also try:
   

   void loop() {
   
       lcd.setCursor(0, 1);
       lcd.print("A");
   }

   which should do print calls faster, and so might stimulate the bug faster.
   You might also try lcd.print("ABCDEFGHIJKLMNOPQRST"); for a similar reason (yes that is deliberately more than 16 characters).

   Often random things can also be electrical or maybe temperature related.

   Is the mini plugged into USB or is it using power into Vin? If it's on external power, what voltage?
   Is the LCD being powered from the mini?
   Is there anything else drawing power from the mini?

   WARNING: I haven't compiled or tested any of that code.

   (Full disclosure: I am not a member of LeafLabs staff.)

   Posted 2 years ago #
3. 

   JCNZL
   Member

   Code is an example for arduino
   just connected it up exactly how its shown in most tutorials 9 RS, EN, DB4, DB5, DB7, DB7 )

   Your ideas make good sense.
   i think it was possible a loose breadboard connection was to blame.

   mini was powered by usb
   lcd powered by usb power also ( 5v, not the 3.3 from the mini )

   i though that it could be handy to add a lcd.begin command to reinitialize the lcd into the loop IF people find this thread and are having the same issue, and cant fix it.

   it will mean that the lcd will fix its self - might take a bit of extra time and be a pain in the bum tho

   or add a button, that is coded to re initialize the lcd ( maybe an interupt process? )

   Thanks again for the help

   Posted 2 years ago #

RSS feed for this topic

Reply

You must log in to post.