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By el ohmbre
#199025
I have a Serial Enabled 20x4 LCD LCD-09568 I'm using with a RedBoard. I read about this lcd before buying it and I understand it has some issues. My application is pretty simple and I have it working OK. However, each time I update my test project and download to the RedBoard, the LCD gets garbage characters and appears to lock up.

Various forum posts and the documentation say to use the softwareserial include file "as shown in the example." I've copied the example and it has exactly the same issue. I can take the generic example, make a trivial change to some text to write to the lcd and when I download, I get the garbage chars, then the dreaded two lines of boxes and it's locked up. I have to remove the usb cable to the RedBoard to rest.

I've tried disconnecting the Rx line before downloading, I've tried disconnected the +5v before downloading. Neither of these things work.

Is there any way to work around this issue. I'd like to be able to make changes to my program and download the updated version without killing the LCD every time.
By paulvha
#199050
it could still be the power supply. During programming it takes higher current than normal working.
Do you have the backlight on? if so, what happens if you turn that off before programming?
Is the LCD the only device connected ? if more, try to test to disconnect the other(s) before
What happens if you connect RX to GND during programming and then reconnect RX to the pin after loading ?
I assume RX is not connected to pin 0 or 1. correct ?
Which speed are you connecting the LCD?
Are you using the splashscreen feature ?
regards,
Paul
By el ohmbre
#199068
Hi Paul, thanks for the response.

I was not intentionally using the backlight feature. I was just using the most basic sample provided in the Hookup Guide which contains no backlight command. I tried sending a backlight command Dec 124 followed by Dec 140 and things got worse. No text displayed at all after the splash screen. I tried some different values with the same result. When I removed the backlight command it went back to normal.

Same thing happened when I tried to turn off the splash screen. It caused no text to appear.

None of the "special character" commands seem to work.

I was doing this with a CAN Bus Shield installed too. I removed it but the results where the same.

Connecting RX to GND had the same effect as disconnecting RC. Screen fills with boxes.

RX IS connected to pin 1 on the RedBoard. Is that wrong?

I tried turning off splash screen with weird results (see above).

Any other thoughts?
By paulvha
#199075
if you use Softserial I would not expect RX to be connected to pin 1, but to the pin you choose in SerialSerial setup. Pin 1 is used for FTDI communication as well. (hard wired with resistors). I would avoid that as that for sure will cause problems when uploading.

That said if you connect RX from the LCD to GND and still have the issues, AND with backlight turned on it gets worse, I get more and more the impression that the supplied power is not strong enough as well. Try to connect a stronger power supply.