Question 1

It it possible to change the address of the lcd to have multiple lcd on the same bus?

Accepted Answer

To further expand on Wes' answer (which is excellent!), you can have up to eight (8) on the same bus, per the chip datasheets. The chips have a portion of the address hard-code (which cannot be changed) and the three remaining address lines (A0, A1, and A2) can be jumpered to ground to set seven (7) other addresses - the 8th being no jumpers. IF you happen to get one with an 8574 chip and another with 8574A or 8574T, then you could potentially have up to 16 modules on the same bus as the A and T versions use a different hard-coded address than the 8574.

Question 2

Has anyone run this display on 3.3 volts successfully? I'd like to use it on an 8266-12E to display the ip address.

Accepted Answer

It works on 3.3V, but just barely: it's unusably dim. I changed the supply voltage to 5V and was able to successfully drive it with 3.3V-level I2C signals, although the PCF8574 data sheet says that the minimum Vih level is 0.7 * Vcc = 3.5V. My scope says that the signals are rising to about 3.8V, so there must be some kind of pull-up to 5V on the I2C backpack board. I don't want to rely on that, so for my final design I'll use a PCA9306 I2C level shifter.

Question 3

Do these come with an I2C backpack?  I just ordered some of these and they came with no backpack in the package.

Accepted Answer

There are several product options on the page, some have I2C, some don't. If you chose one that has I2C, it should come with an I2C backpack.

Question 4

Does this work for the old raspberry pis that have a 26 pin gpio?

Accepted Answer

This module uses an i2c serial interface rather than discrete gpio pins.  If your rpi has an i2c, it should work.

ASIN	B019K5X53O
Best Sellers Rank	#246,479 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #90 in LCD Character Modules
Brand	SunFounder
Brand Name	SunFounder
Compatible Devices	Arduino R3 Mega 2560
Connectivity Technology	I2C
Customer Reviews	4.5 out of 5 stars 435 Reviews
Manufacturer	sunfounder
Manufacturer Part Number	TS0351
Memory Storage Capacity	1 TB
Model Name	IIC I2C TWI 1602
Model Number	TS0351
Network Connectivity Technology	I2C
Processor Count	1
UPC	701715367685
Wireless Communication Standard	802.11b
Wireless Compability	802.11b

SunFounder IIC I2C TWI 1602 Serial LCD Module Display Compatible with Arduino R3 Mega 2560 16x2

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