I2Cexpdiag shows "No working LCD"

I cannot see any text on my LCD when using I2C.

  • LCD works when connected directly to the Arduino

  • MC is ElEGOO Uno R3

  • Backpack is PCF 8571T

  • LCD is the one that comes with the Arduino starter kit (I couldn't find any ID on it).

  • I followed Bill's great instructions to run I2Cexpdiag

Here's the report from I2Cexpdiag:


Serial Initialized

I2CexpDiag - i2c LCD i/o expander backpack diagnostic tool

hd44780 lib version: 1.1.1

Reported Arduino Revision: 1.8.12
CPU ARCH: AVR - F_CPU: 16000000

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

Checking for required external I2C pull-up on SDA - YES
Checking for required external I2C pull-up on SCL - YES
Checking for I2C pins shorted together - Not Shorted

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
LCD stuck BUSY status

No working LCD devices


  • I see 16 squares on the top line (2,16) line of the LCD.
  • Second line is blank.
  • I've carefully examined and cleaned all solder joints
  • The PCB foil beneath DB1 on the LCD could be damaged but I don't think so

Thanks for looking,
-t

LCD Display Memory Test
Display: 0
LCD stuck BUSY status

See this thread on the "stuck BUSY" status