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Parallax 2x16 Serial LCD (Non-Backlit) suddenly stopped working — Parallax Forums

Parallax 2x16 Serial LCD (Non-Backlit) suddenly stopped working

macfreakmacfreak Posts: 3
edited 2011-08-02 19:08 in BASIC Stamp
:confused: My son opened a brand new 2X16 yesterday and it was working fine. Today it suddenly stopped working. What could have caused this? Does it overheat? He's been careful about static and water. The debug makes the display show black rectangles but his programme is no longer working. He's using it on the basic stamp 2 school kit.

Sorry - but this is a non-technical mom trying to help out a heartbroken 9 year old. Any help to at least prevent this from happening again if he did something to break it, would be very appreciated. :smile:

Comments

  • Dr. MarioDr. Mario Posts: 331
    edited 2011-07-28 18:32
    Well, yes it can overheat if incorrectly wired up.
    I assume that your son have been wiring it correctly. Did your son try out the programming routine that call for the LCD display? And, that's good that he knew about the electrostatic discharge, so I wouldn't worry about that.

    There are more than one way to blow the LCD controller up. Voltage going out of specs is one way to do that. If necessary, go by the datasheet to make sure. I did some tricks when I was younger, I usually hit the 3.3V LCDs with two AA batteries, and for 5V ones, three AA batteries. However, I would personally prefer that you guys get a clean voltage regulator (for battery power) or better switchmode power supply - it needs to stay within 10% of listed power. Please give me a bit more details of how it failed (like lines going squiggy or just few pixels appearing out of nowhere), I would help you out.
  • graffixgraffix Posts: 389
    edited 2011-07-28 21:49
    Welcome to the forums macfreak
    could be a couple of things more detail is needed,it may even be ok?
  • WBA ConsultingWBA Consulting Posts: 2,934
    edited 2011-07-28 22:24
    If you are "seeing little lack squares" on the LCD, the contrast may need to be adjusted. The back of the LCD has an adjustment pot. Rotate that back and forth to see if the display changes so you can see the proper characters. One of my non-Parallax LCDs had a really touchy pot so if it wasn't adjusted just right, it would show blocks across the screen (meaning that all character pixels were solid on)
  • Dr. MarioDr. Mario Posts: 331
    edited 2011-07-28 22:35
    WBA, that too. Thanks for pointing out, I forgot about that.

    I think the RS232 handshaking routine also is timing sensitive, but if you guys have seen the words or anything that was displayed once the BASIC's processing the routine, I would rule the timing out - contrast pot and specified voltage would be the suspect, however.
  • macfreakmacfreak Posts: 3
    edited 2011-07-29 09:47
    Hi everyone - thanks for your responses. He was using a 9V battery and used his voltage meter to check that it was within specs, which it apparently is. The unit was working perfectly until he unplugged from the computer and changed locations, which makes me think it's a voltage spike and the processor is fried.

    What other information would be helpful?
  • LeonLeon Posts: 7,620
    edited 2011-07-29 10:20
    Write a simple program to check that the Stamp is working properly.
  • macfreakmacfreak Posts: 3
    edited 2011-07-29 10:48
    His 5 position switch and LEDs are working - so I don't think it's the stamp module. Should I cut and paste the programme he was running when the problem ocurred?
  • LeonLeon Posts: 7,620
    edited 2011-07-29 11:02
    I don't think that would help. I'd contact Parallax directly, they will probably replace the LCD.
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-07-29 11:03
    Not to berate you, but, as first described all was well and then, inexplicably, all went to pot ("...it suddenly stopped working.")
    Now, as it turns out, it was unplugged and placed in another location.
    So, something changed.
    [Check, check, and re-check, and check it again.]
  • Dr. MarioDr. Mario Posts: 331
    edited 2011-07-29 12:00
    Good, that's good that it's within the specs.

    However, I would suspicious of ESD - it doesn't take a lot to fry certain model of LCD. And, on other hands, you would also want to check that it doesn't require the clock - some LCD module get rather unhappy quickly if it's not driven by external clock (I have fried few before.... At least it was out of junk electronics.)

    Just had to say of something that may not be listed, you know?

    However, good news is that you can replace it under warranty.
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2011-07-29 13:37
    Sorry - but this is a non-technical mom trying to help out a heartbroken 9 year old. Any help to at least prevent this from happening again if he did something to break it, would be very appreciated. <........... Your doing great for being a non-technical mom :smile:

    One other thing to check is the baud rate on the LCD Display matches the baud rate in his program code that he is using

    One thing may have happen is that there are three wire plug two are are power and the other wire is the( Data wire which is the out side wire) if the Stamp Board side and the LCD display do not match pin for pin then you will fry the LCD display

    I know because it happen to me once

    Just call Tech support and see what they can do for you
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-07-31 09:07
    I can't recall any discussion of it, but - with a Rev.E (or earlier) it's destructive to have data present on the "RX" pin without having 5V applied. So, if the connection to 5V (i.e. BoE's "Vdd") wasn't solid, then it's a problem.

    Here's where someone may run into trouble:
    If a Rev.E-type is connected to the BoE through one of the servo ports and the slide switch was in the middle, position 1, instead of all the way over to position 2, then great sorrow would result as there's no power (5V) to the servo ports till the switch is in position 2.

    [ Only Rev.F boards have a beeper on the serial/piggy-back board. ]
  • Dr. MarioDr. Mario Posts: 331
    edited 2011-07-31 12:43
    That really sucks.... I hope macfreak may have better luck of getting recent version of LCD module once the fried one is being traded in under warranty for better one. PJ Allen, I really felt that it would be the case of having finite-state machine chip on the LCD, they're so finicky about how it should be set up, both electrical power and data... Some LCD modules have the actual 8-bit CPUs, and they really don't care how it is being set up.
  • Jimmy LiebJimmy Lieb Posts: 46
    edited 2011-08-02 19:08
    Does parallax still offer a half price replacement, even if it is user error? I know they used to.

    The first LCD screen i bought was a 2 or 3 dollar one off eBay. I didn't understand the concept of serial, and tried to use 3 pins, because I found the datasheet for that same model, only serial. The back light flashed really brightly, and then it was dead:/ Oh well.

    I have had a Rev. E serial 4X20 display for a long time, and never realized about the dangers of the BOE's 3 pin headers. thanks PJ Allen!

    Good luck, I'm sure that parallax will help. their customer support by far surpasses any other company I have worked with.

    ~Jimmy
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