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tinyLCD_I2C
===========
Description:
------------
tinyLCD_I2C is a Firmware for LCD I2C backpack based on ATtiny84 with an Arduino library as drop-in replacment for the LiquidCrystal library.
Instructions
------------
Please make sure to use the TinyWireS library from this repo with the ATtiny implementation from
http://code.google.com/p/arduino-tiny/
Also you should make the following change in ./hardware/tiny/cores/tiny/wiring.c to improve performance of the TinyWireS library:
```ISR(MILLISTIMER_OVF_vect)
{
sei();
// copy these to local variables so they can be stored in registers
// (volatile variables must be read from memory on every access)
```
Basically add the line
```
sei();
```
to the *ISR(MILLISTIMER_OVF_vect)* function so that it looks like above excerpt.
See http://forum.boxtec.ch/index.php/topic,2225.msg2845.html#msg2845 for a discussion on this issue.
Boards / PCBs
-------------
The boards directory contains a Fritzing THT design on which current development is based and an Eagle 6.x SMD design which is currently in production for first prototypes.
BOM
---
THT-Board:
- 220nF Cer Cap
- 100k, 4.7k, 150R
- ATtiny84A-PU
- 28 Pin DIP socket (optional)
- Header female (16pins)
- 2x3 Pin Header male
SMD-Board:
- 220nF Cer Cap
- 100k, 4.7k, 150R
- ATtiny84-SU (SOIC)
- Header female (16pins)
- 2x3 Pin Header male
Forum / contact
---------------
Issues around the tinyLCD_I2C board and firmware can be discuess here:
- http://forum.boxtec.ch/index.php/topic,2225.0.html
Credits
-------
Credits go to ..
.. *brohogan* for bringing the [TinyWireS library](http://playground.arduino.cc/Code/USIi2c) to life in the first place.
.. pylon for fixing all the timing issue and race conditions in above library and enhancing the tinyLCD_I2C greatly (i.e. by adding SPI)
.. MathiasW for adding a SMD design with reduced size