LCD - I2C issues after upgrading to Arduino IDE 1.8.1.

Other Hardware Displays
1

Hi

My LiquidCrystal_I2C lib is no longer working after upgrading from arduino IDE 1.6.0 to 1.8.1. LCD turns on but no letters.

I have downloaded and installed hd44780.h as recommended by Bill Perry. (see discussion here: http://forum.arduino.cc/index.php?topic=447203.0)

Then I ran the "hello world" example from hd44780_I2Cexp. Modified rows to 4 and cols to 20 (my LCD is 20x4). But nothing displays, my LCD screen turns on, but no letters.

Tried with arduino nano ATMega328 with CH340G processor, and arduino Uno, same issue. My LCD is connected thorugh an I2C module with SDA on A4 pin and SCL on A5 pin.

I ran the I2CecpDiag and got this. The LCD still diplays nothing, but blinks 3 times, then turns on again.

Serial Initialized

I2CexpDiag - i2c LCD i/o expander backpack diagnostic tool

hd44780 lib version: 0.8.3

Reported Arduino Revision: 1.8.1
CPU ARCH: AVR - F_CPU: 16000000

A4: digital pin: 18
A5: digital pin: 19
SDA: digital pin: 18
SCL: digital pin: 19

Checking for required external I2C pull-up on SDA - YES
Checking for required external I2C pull-up on SCL - YES

Scanning i2c bus for devices..
i2c device found at address 0x27
Total I2C devices found: 1

Scanning i2c bus for all lcd displays
LCD at address: 0x27 | config: P01245673H | R/W control: Yes
Total LCD devices found: 1

LCD Display Memory Test
Display: 0
Walking 1s data test: PASSED
Address line test: PASSED

Each working display should be displaying its #, address, and config information
If display is blank, but backlight is on, try adjusting contrast pot
If backlight is off, wait for next test

Blinking backlight test: to verify BL level autodetection
If backlight is mostly off but
you briefly see "BL Off" on display with backlight on,
then the library autodetected incorrect BL level
and the library cannot autoconfigure the device

Displaying 'uptime' on all displays

Hardware problem maybe? My display is from ebay here: http://www.ebay.com/itm/HOT-Serial-IIC-I2C-TWI-2004-LCD-20X4-Character-LCD-Module-For-Arduino-bxmc/

Thank you a lot for your help.

Sebas

2

The diag sketch has verified that the library can communicate properly with the LCD so that really limits what can be causing issues.

You have not fully described what you are seeing on the display.
Do you see any pixels on at all?

And you have not said what happened when you adjusted the contrast pot.

Given the diags is passing, and you said the backlight is on, then about the only thing left that can be causing an issue is the contrast circuit.
Have you adjust the contrast pot?
At one end all the pixels should always be on, at the other no pixels will ever be on.
Some where in the middle, the display pixels that are supposed to be on will be on and the ones that are supposed to be off will be off.

--- bill

3

Main computer with recent install of IDE 1.8.1 wouldn’t drive the 1602 LCD I2C. Same sketch on my netbook 1.6.12 works fine. New guy so don’t know, something different about the I2C between the versions?

4

Hi Bill

Thank you very much for your reply. I adjusted the contrast and the words appeared. This was so simple, sorry for disturbing...

A little bit strange that the needed contrast to see the words varies between libraries. Did not expect that, but I'm new in this stuff.

Best

Sebas

5

sebulox:
A little bit strange that the needed contrast to see the words varies between libraries.

The library should not affect the contrast or the contrast pot adjustment.
There is nothing that the s/w can do to adjust/affect contrast.
My guess is something else other than s/w changed that is influencing it.
For example, the contrast is sensitive to the power supply voltage.

I'd bet that if you switch libraries without changing anything else, the backpack would need the same contrast pot adjustment.

--- bill