GLCD via 12c

Other Hardware Displays
1

I have been trying to get Nick Gammon’s GLCD via 12c project going without much success.

I know that there have been other threads dealing with this issue but I cannot find them
This is the display that I am using

and I know that it is good because I have used it with the GLCD 3 library with no problems thanks to Bill Perry. I have rechecked the wiring and it all seems to be good with the backlight working and I can adjust the contrast pot and see the individual pixels. The code will upload but there is nothing showing on the display. I used the 12c scanner at

Arduino Playground - I2cScanner and got

“I2C Scanner
Scanning...
No I2C devices found”

I am using the 12c connection method with the MCP23017 chip and the GLCD display (type B) has the same connections as the one used in Nick’s project. Can anyone offer any suggestions as to what I might be doing wrong. I have attached a photo of my setup but I don’t know if it will be any help

thanks Pedro.

GLCD via 12c.jpg
GLCD via 12c.jpg2048×1536 789 KB

2

No I2C devices found”

I don't see any pull-up resistors on your two I2C lines (SDA and SCL). If you are using the internal ones they may not be sufficient.

Don

3

Thanks Don.

I have not used the internal pull ups before, so how do I enable them and also I would prefer to add some external resistors so what value would you recommend and do I tie them high?

Thanks Pedro.

4

Thanks a lot Don.

I put some 4K7 resistors on the two I2C lines and it is working well. Have a good day (you guys are great)

Pedro 8)

Thanks Nick Only Two Control Lines.jpg
Thanks Nick Only Two Control Lines.jpg2048×1536 762 KB

5

Pedro147:
I have not used the internal pull ups before, so how do I enable them and also I would prefer to add some external resistors so what value would you recommend and do I tie them high?

If you're still interested, after fixing the pinMode as INPUT, digitalWrite that pin HIGH (and, yes, you read that right.)

6

Thanks Runaway, still trying to get my head around your Larson Scanner code 8) tricky