Matrix Orbital Corp

Hello all,

I am trying to get my LCD working using I2C and have simply been unable to get it working. I have soldered the jumpers for I2C and removed the jumpers on 232. I have tried connecting to various I2C platforms the latest being the Wiring/Processing platform.

I have used the I2C address 0x50 >> 1

At the hardware level when I check the SCL line with a scope I see the clock pulse when the line is not connected to the LCD. When I connect the SCL line to the LCD the clock pulse is no longer visible and the voltage on the line basically drops to 0 v (350mV)

I have successfully connected to other I2C devices namely the BlinkM so my code seems to work.

Does anyone have any other ideas? Have I missed something in the changes needs to the LCD board?

Kind thanks,
Serge

OK,

So I just found this.

http://www.matrixorbital.ca/PCNs/glkglc ... -25-SM.pdf

However, it talks about lifting pin 13 of the SP232 and if you look at the pictures in the PDF you have actually lifted pin 12.

So now I dont know which one to lift. I have lifted pin 12 but I still don't have I2C working. Before I re-solder pin 12 and lift 13 I would like to know the correct one.

Thanks,
Serge

Sorry, getting late. I miscounted the pins.

I will keep digging to see why its still not working.

Thanks,
Serge

Hi Serge,

Looks like you've been working through this one on your own, the PCN document should have all the tricks you need to get that older unit into I2C mode. If you do have any trouble with communication once you get it all wired up, please feel free to throw up another post.

Thanks,
~Troy

Thanks, I now have this working against an Arduino!

My next hurdle is getting this connected to a non 5v tolerant I2C master....

Thanks,
Serge

Can anyone tell me if I need pullup resistors on the LCD side to 5v ?

Thanks,
Serge

Never mind

Issues solved

Thanks,
Serge

Glad to hear!