I2C + Multiple Character Lcds, encoding

by platypus on Sat Feb 16, 2013 1:19 am

Successfully got the 16x2 and 20x4 character lcds working with the I2C backpack.
Yes you do need to be careful in setting lcd.begin(16,2) or lcd.begin(20,4) else, well, spaghetti display!

Now looking at configuring multiple Lcds on the I2C bus.

What is the limiting number of Lcds that can be supported - the tutorial says 7 - but where does this limit of 7 come from?

Is there example code and method to configure multiple Lcds?

Thanks
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Re: I2C + Multiple Character Lcds, encoding

by adafruit_support_bill on Sat Feb 16, 2013 7:37 am

See "Changing the I2C address" at the bottom of the tutorial page: http://learn.adafruit.com/i2c-spi-lcd-b ... ect-to-i2c
The A1, A2, A3 address pads referred to in the tutorial are on the lower left of the board.
Image

What is the limiting number of Lcds that can be supported - the tutorial says 7 - but where does this limit of 7 come from?

The chip supports 3 bits of addressing. I haven't tested it, but I believe you can actually have up to 8, since 3 bits of addressing allow for addresses from 0 to 7.
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Re: I2C + Multiple Character Lcds, encoding

by platypus on Sun Feb 17, 2013 3:30 am

That's great, thanks - I missed the bcd encoding when I glanced through it.

Yes that encoding should work - I think the limit is with the chip, but that's fair enough - 7 lcds should be sufficient.

Do you stock a 40x4, 16 pinout lcd, compatible with the I2C backpack?
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Re: I2C + Multiple Character Lcds, encoding

by adafruit_support_rick on Sun Feb 17, 2013 3:56 pm

The largest LCD we stock is the 20x4.
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