ATTiny85 I2C LCD

Question

My setup is as follows:

Arduino IDE 1.6.11
Arduino Pro Mini as ISP
ATTiny85 1602A LCD with I2C board

The libraries I use are:

TinyWireM (source: https://github.com/adafruit/TinyWireM)
LiquidCrystal_I2C (modified for ATTiny) (source: http://playground.arduino.cc/Code/USIi2c)

The Sketch I use to test with:

#include <TinyWireM.h>                 
#include <LiquidCrystal_I2C.h>         

LiquidCrystal_I2C lcd(0x3F,16,2);  // set address & 16 chars / 2 lines

void setup()
{

  TinyWireM.begin();                    // initialize I2C lib
  lcd.init();                           // initialize the lcd 
  lcd.backlight(); 
  lcd.clear();  // Print a message to the LCD.
}

void loop()
{
  lcd.setCursor(0, 0);
  lcd.print("Hello World on Attiny85");
  delay(2000);
}

The address is 0x3F, I found this using the scanner sketch, I also tested the LCD using the Arduino Pro Mini directly, it works fine.

The result of this setup is a single line of black blocks. My guess is that the initialization failed in some way. I have tried some things to make it work:

Pull-ups on SDA and SCL
Isolated from Arduino with regulated power supply
Setting contract with the pot meter on the back
reinstall of PC
reinstall of Arduino IDE
1MHz, 8Mhz, TinyCore default and High-Low Tech
Replaced FTDI
Replaced Tiny85
Replaced LCD
Replaced Arduino Pro Mini

Some pictures:

[EDIT]

Final sketch:

#include <TinyWireM.h>                  // I2C Master lib for ATTinys which use USI
// #include <LiquidCrystal_I2C.h>
#include "LiquidCrystal_attiny.h"
LiquidCrystal_I2C lcd(0x27,16,2);

void setup() {

  // Now set up the LCD
  //lcd.begin(16,2);               // initialize the lcd
  pinMode(4, OUTPUT);
  lcd.init();
  lcd.backlight();
  lcd.home ();                   // go home
  lcd.print("Weatherstation");
  lcd.setCursor ( 0, 1 ); // go to position
  lcd.print("BMP180");
  delay(2000);
}
void loop() {
  digitalWrite(4, HIGH);
  delay(100);
  digitalWrite(4, LOW);
  delay(100);
}

score 4 · Accepted Answer · answered Oct 03 '16 at 18:21

After hours of Googling, I found a blog post by Dimitris Platis where he describes using an ATTiny85 with I2C LCD. I emailed the guy and he replied with a link to his LCD I2C ATTiny library on GitHub. Using this library with the TinyWireM and the right core, it instantly worked.

My final setup is with a 4.7K resistor on SDA and SCL, I will add the final sketch in the original post under [EDIT]. This adventure took me two weeks so I hope it helps someone else some day.

LCD library used: https://github.com/platisd/ATtiny85-LCD-library
TinyWireM used: https://github.com/adafruit/TinyWireM
Core used: https://github.com/vprimachenko/ArduinoTiny

score 0 · Answer 2 · answered Oct 04 '16 at 19:55

0

It doesn't look like you have an Arduino Pro Mini. I2C lines on a Pro Mini are on pins A4 for SDA and A5 for SCL and those 2 pins are placed at an odd location - check picture.

Hope I was helpful :)

answered Oct 04 '16 at 19:55

score 0 · Answer 3 · answered Dec 19 '20 at 08:43

0

I've spent an hour doing this problem and searched a lot. If you still didn't find the solution by doing this. Pls try to reduce the clock speed from Internal 8 MHz to Internal 1MHz. That way it works mine.

answered Dec 19 '20 at 08:43

Player1

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ATTiny85 I2C LCD

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