avr-io

Firmware for the ATmega328P which allows it to function as an I2C device and have it's pins controlled via I2C. When running the firmware, the ATmega can be accessed at it's default address of 0x28 on an I2C-bus.

When the ATmega328P is clocked at 8MHz, the firmware will function on an I2C-bus running at speeds of up to 100KHz without stretching the I2C clock.

Usage

Blink an LED:

var i2c = require('i2c-bus').openSync(1);

var OUTPUT = 1;

var AVR_ADDR = 0x28,
  P8_MODE = 0x20,
  P8_VALUE = 0x21;

i2c.writeByteSync(AVR_ADDR, P8_MODE, OUTPUT);

setInterval(function () {
  i2c.writeByteSync(AVR_ADDR, P8_VALUE,
    i2c.readByteSync(AVR_ADDR, P8_VALUE) ^ 1);
}, 500);

Pin Function Descriptions

Register Map

Address	Name	Reset Value	Arduino Pin	ATmega328P Pin	Description
0x00	P0_MODE	INPUT	0	2	Mode pin 0
0x01	P0_VALUE	0 or 1	0	2	Value pin 0
0x04	P1_MODE	INPUT	1	3	Mode pin 1
0x05	P1_VALUE	0 or 1	1	3	Value pin 1
0x08	P2_MODE	INPUT	2	4	Mode pin 2
0x09	P2_VALUE	0 or 1	2	4	Value pin 2
0x0c	P3_MODE	INPUT	3	5	Mode pin 3
0x0d	P3_VALUE	0 or 1	3	5	Value pin 3
0x10	P4_MODE	INPUT	4	6	Mode pin 4
0x11	P4_VALUE	0 or 1	4	6	Value pin 4
0x14	P5_MODE	INPUT	5	11	Mode pin 5
0x15	P5_VALUE	0 or 1	5	11	Value pin 5
0x18	P6_MODE	INPUT	6	12	Mode pin 6
0x19	P6_VALUE	0 or 1	6	12	Value pin 6
0x1c	P7_MODE	INPUT	7	13	Mode pin 7
0x1d	P7_VALUE	0 or 1	7	13	Value pin 7
0x20	P8_MODE	INPUT	8	14	Mode pin 8
0x21	P8_VALUE	0 or 1	8	14	Value pin 8
0x24	P9_MODE	INPUT	9	15	Mode pin 9
0x25	P9_VALUE	0 or 1	9	15	Value pin 9
0x28	P10_MODE	INPUT	10	16	Mode pin 10
0x29	P10_VALUE	0 or 1	10	16	Value pin 10
0x2c	P11_MODE	INPUT	11	17	Mode pin 11
0x2d	P11_VALUE	0 or 1	11	17	Value pin 11
0x30	P12_MODE	INPUT	12	18	Mode pin 12
0x31	P12_VALUE	0 or 1	12	18	Value pin 12
0x34	P13_MODE	INPUT	13	19	Mode pin 13
0x35	P13_VALUE	0 or 1	13	19	Value pin 13
0x38	P14_MODE	INPUT	A0	23	Mode pin A0
0x39	P14_VALUE (LSB)	0 or 1	A0	23	Value pin A0 (LSB)
0x3a	P14_VALUE (MSB)	0	A0	23	Value pin A0 (MSB)
0x3c	P15_MODE	INPUT	A1	24	Mode pin A1
0x3d	P15_VALUE (LSB)	0 or 1	A1	24	Value pin A1 (LSB)
0x3e	P15_VALUE (MSB)	0	A1	24	Value pin A1 (MSB)
0x40	P16_MODE	INPUT	A2	25	Mode pin A2
0x41	P16_VALUE (LSB)	0 or 1	A2	25	Value pin A2 (LSB)
0x42	P16_VALUE (MSB)	0	A2	25	Value pin A2 (MSB)
0x44	P17_MODE	INPUT	A3	26	Mode pin A3
0x45	P17_VALUE (LSB)	0 or 1	A3	26	Value pin A3 (LSB)
0x46	P17_VALUE (MSB)	0	A3	26	Value pin A3 (MSB)

Modes

Number	Name
0	INPUT
1	OUTPUT
2	ANALOG
3	PWM
5	INPUT_PULLUP

Supported Modes

Arduino Pin	Modes
0	INPUT, OUTPUT, INPUT_PULLUP
1	INPUT, OUTPUT, INPUT_PULLUP
2	INPUT, OUTPUT, INPUT_PULLUP
3	INPUT, OUTPUT, INPUT_PULLUP, PWM
4	INPUT, OUTPUT, INPUT_PULLUP
5	INPUT, OUTPUT, INPUT_PULLUP, PWM
6	INPUT, OUTPUT, INPUT_PULLUP, PWM
7	INPUT, OUTPUT, INPUT_PULLUP
8	INPUT, OUTPUT, INPUT_PULLUP
9	INPUT, OUTPUT, INPUT_PULLUP, PWM
10	INPUT, OUTPUT, INPUT_PULLUP, PWM
11	INPUT, OUTPUT, INPUT_PULLUP, PWM
12	INPUT, OUTPUT, INPUT_PULLUP
13	INPUT, OUTPUT, INPUT_PULLUP
A0	INPUT, OUTPUT, INPUT_PULLUP, ANALOG
A1	INPUT, OUTPUT, INPUT_PULLUP, ANALOG
A2	INPUT, OUTPUT, INPUT_PULLUP, ANALOG
A3	INPUT, OUTPUT, INPUT_PULLUP, ANALOG