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Topics - m3atwad

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Character LCDs / NHD-0420D3Z-NSW-BBW-V3 not responding to I2C
« on: October 16, 2014, 03:56:18 PM »
Hello,

I'm using the LCD listed in the title.  I have installed a 0R jumper for R1 and can't seem to get this LCD to acknowledge (I"m getting a NACK) when I send 0x50 over the I2C port.  The LCD is powered with 5.0V and the I2C signals (SCL/SDA) are 3.3V.  I wouldn't think this would require a 5V I2C signal.  I've gone through data sheet multiple times and checked all of my connections.  If I attach an MSP430 microcontroller on the same bus as a slave with a different address it responds no problem.  I then change  the addres to 0x50 and nothing.  I've even let it run for a while and implemented large delays.  I haven't gotten to any commands yet I'm just stuck on getting the LCD to acknowledge it's address byte.  I'm not sure where to go here.  I've also tried shifting the address to the left one in case the data sheet meant the "address" as in the top 7 bits are supposed to be 0x50 and the R/W bit is 0 yielding 0xA0 being the first byte you sent for both address and R/W.  Nothing from that either.

On the scope I'm seeing this:

Start Condition | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | NACK

This part is brand new from digikey and I haven't issued any commands to it so far.  It does look like it powers up correctly.  Screen looks good and bright.  Nice blue background etc...

Thanks,
Rob

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