Hello Arduino Fans,
I was wondering if it;s possible to have 2 Arduino Serial IIC/I2C/TWI 2004 204 Character LCD Module with an Arduino Uno R3.
Since the specs states that the device address is 0x27 I think that it is not possible. Please confirm!
Thanks
8)
Perfectly possible. You can use up to eight of them.
You just have to change the address jumpers. If the "backpack" module does not have address jumpers (but it likely does), you have to identify the address select pins on the chip and jumper those accordingly which admittedly, is a trifle more challenging.
Of course if you were to disclose the link to which module you are using, or even a (decent, perfectly focused and posted at no more than 1024 by 768 resolution) photograph of the backpack, it would be more definite to advise.
There ya go
http://hardware-analyst.com/2014/04/18/photo-share/
For some reason using the insert image feature for this post editor truncates the image? even at 1024 by 768
See the solder jumpers labeled A0, A1, A2 on your backpack?
Those are the A0, A1, A2 pins on the PCF8574 chip.
That is how you set the lower 3 bits of the i2c address for the chip.
http://www.nxp.com/documents/data_sheet/PCF8574.pdf
If you put a solder blob across the vertical pads it will alter the i2c address.
Then there are 3 address bits using A0, A1, and A2 that set the lower 3 bits of the i2c address
which you can set to allow up to 8 chips to be addressed on the same i2c bus.
If you have an i2c address of 0x27, then
more than likely the chip has a base address of 0x20 and
the three 10k resistors you see along the bottom of the board marked 103
are pullups on the A1,A1, and A2 pins which sets them all to 1
which sets the final address of the chip to 0x27.
To change the address, all you need to do is put some solder
(a blob that bridges the upper and lower pads)
on one or more of the A0, A1, A2 solder jumpers.
This will allow you to select an i2c address between 0x20 to 0x27
example, a solder blob on A0 would change the address from 0x27 to 0x26
a solder blob on A1 would change the address from 0x27 to 0x25
a solder blob on A2 would change the address from 0x27 to 0x23
a solder blob on all of them would change the address from 0x27 to 0x20
etc...
--- bill
Is it ok to jump here as showed in RED
No.
Vertical is up and down not horizontal.
--- bill
So I can JUMP vertically
A0
AND/Or
A1
AND/Or
A2
Correct?
8)
Please confirm. Thanks
Different people are on different tine zones - or have to go to work!
Yes, A0 is the two pads above the lettering, as for A1 and A2. Jumpering each of the three pairs with solder pulls down the corresponding address line on the chip, otherwise pulled up by one of the (nearby) resistors (I can't seem to lay my hands on that particular board just now to trace them out). A0 has the value "1", A1 the value "2" and A2 the value "4" in the actual address, there are eight possible combinations (including no jumpers) giving you eight possible addresses.
Excellent news. Sorry for being impatient 
Thanks for the update.