I2C LCD Library... Help!

Discuss development of drivers for external hardware and components, such as LCD screens, sensors, motor drivers, etc.
Target audience: Users and developers of drivers.
raspi3ua
Posts: 10
Joined: Sat Mar 18, 2017 4:49 pm

Re: I2C LCD Library... Help!

Postby raspi3ua » Sat Mar 18, 2017 9:28 pm

One of comments from Aliexpress:
"3f address. there is written about it. put the address 0х3f i2c module and start-everything works. https://ae01.alicdn.com/kf/UT8QpQBXNNaXXagOFbXQ.jpg"

So adress 63 is OK.


"The part number of the 0x3F chip will be PCF8574. i.e.0x38-0x3F
The part number of the 0x27 chip will be PCF8574A i.e. 0x20-0x27"
http://forum.arduino.cc/index.php?topic=369998.60


picture: https://cdn.instructables.com/FVV/YTFX/ ... .LARGE.jpg
0x3F - my code.
PCF8574AT - my backpack.

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dhylands
Posts: 2260
Joined: Mon Jan 06, 2014 6:08 pm
Location: Shuswap, BC, Canada
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Re: I2C LCD Library... Help!

Postby dhylands » Sat Mar 18, 2017 10:09 pm

SDA and SCL both need pullup resistors. Some boards have them and some don't. I'd try adding 10K ohm pullups between 3.3v and SDA and also between 3.3v and SCL.

raspi3ua
Posts: 10
Joined: Sat Mar 18, 2017 4:49 pm

Re: I2C LCD Library... Help!

Postby raspi3ua » Mon Mar 20, 2017 8:30 am

I soldered all pins from LCD to backpack and now all is ok. :-)
Thanks for troubleshuting.
LED_front1.jpg
LED_front1.jpg (185.53 KiB) Viewed 23 times


>>> from esp8266_i2c_lcd import I2cLcd
>>> from machine import Pin, I2C
>>> i2c = I2C(scl=Pin(5), sda=Pin(4), freq=100000)
>>> i2c.scan()
[63]
>>> lcd = I2cLcd(i2c, 63, 2, 16)
>>> lcd.clear()
>>> lcd.putstr(' Thanks from Ukraine :-) ')


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