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Topic: How to use this PCF8574 board from "emall-4u" (Read 3 times) previous topic - next topic


This is labeled LCM1602-IIC.

The address and the sample code are, not surprisingly, wrong.  The address of the one that I am using is 0x20, not 0x27, and you do have to set up the pins in order.  My Arduino Serial board has its SCL on A0, and its SDA on A1.

I traced the connections using an ohmmeter, and here is the correct line of code.  First I track all the relevant pins to the chip, then I use the chip's documentation to find out which of the P0 to P7 chips it is.  It is not nearly as easy to trace the pin that controls the backlight, but there are eight possibilities, seven already traced, so it's the one that is left.  I have it working and properly backlit:

LiquidCrystal_I2C lcd(lcdAddr, 2,1,0,4,5,6,7,3, POSITIVE); // addr, EN, RW, RS, D4, D5, D6, D7, Backlight, POLARITY for mall4 adapter

Just in case anyone might need the information. 

This is the adapter:  http://www.ebay.com/itm/390527380190?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649


Which library?
Based on the constructor, I'm assuming it is fm's library but It would be useful to also say which library is used (a link to the library would be even better).
--- bill


The address of the one that I am using is 0x20, not 0x27, ...

It looks like you may be able to change the address from 0x20 to 0x27, or to any of the other six addresses in between, by dealing with the solder blobs above A0, A1 and A2. 



Im also using the emall4u board. It's not working with the pins you posted. What screen are you using? Also im using a Nano-board. Wich seems to also cause problems for some people :)

Since the backlight turns on i gather that the arduino and IIC are talking. Wich leaves 2 options. The pins are wrong or there is something wrong with the IIC-board.

Since i get two out of 4 lines filled with black blobs, im leaining against option number one...

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