I am working on an engine controller and I need to set some soft parameters in EEPROM. After talking to the person for whom the device is being constructed, we decided to use a dollar store $1 universal remote control and the Sony IR protocol. The MIM sensor in the Subject line is the one I selected because I happened to have several in my parts box from a PICAXE project. My sensors came from http://www.goldmine-elec-products.com/prodinfo.asp?number=G16737 at a time when they were on sale for 10x for much less than the qty 1 price.
In researching the Arduino code, I came across a number of Forum posts as well as Adafruit and SparkFun. The SparkFun code seemed to be usable but upon downloading I noticed they had taken the code from the Forum: http://arduino.cc/forum/index.php/topic,17965.0.html Thank you pmalmsten and other contributors of that thread.
My design for the engine monitoring uses a Mega2560 and monitors 16 sensors ranging from EGT over SPI to Time/Date over I2C. I really did not want interrupt driven code, so the function getIRKey() was ideal. However, to have a decent responsiveness "feel" I did not want to poll the code in the Mega2560. I thought about using a cheap 328P off-board and then I got the idea of rewriting the code to use the ATtiny85 and the internal 16MHz oscillator fuses. I selected the Arduino-Tiny hardware core from http://code.google.com/p/arduino-tiny/ and made a few changes to the code to manage the pinout. The code works and while I am likely to make a few modifications, I wanted to post since there may be others who could benefit from off-loading IR decoding to a separate, inexpensive ATmel uC while still managing the code in the Arduino GUI.
You must select the correct "board" type... ATtiny85@16MHz (internal PLL)
(I have not tried other options... your mileage may vary.)
PLEASE... I am NOT an ATtiny kind of person... so, if you have questions about ATtiny85 and Arduino, please research this Forum and consult the arduino-tiny information on the Google hosting link. If you still are in need, try posting on the Forum and perhaps the author Coding Badly or another enlightened member will respond with appropriate information.
I found that following the instructions provided with the download were sufficient for my needs.
- Ray
OK, the code for the ATtiny85:
(9600BAUD serial output comes off of ATtiny physical pin# 7)
/*
IR remote control (Sony) detection for Arduino, M. Burnette
Binary sketch size: 2,794 bytes (of a 8,192 byte maximum)
? 20130103 MRB Modified for interface to Mega2560
Europa codebase for menu system
? 20121230 MRB Modified for Tiny85 Google Tiny library
Tiny85 Internal RC 16MHz
? 20121230 MRB modifications to adapt to numeric input, avoid dupes,
and to generally "behave" consistently
? Used with Electronic Goldmine IR detector MIM 5383H4
http://www.goldmine-elec-products.com/prodinfo.asp?number=G16737
? IR detector:
Pin 1: To pin D4 on Arduino ATtiny85
Pin 2: GND
Pin 3: 5V through 33 Ohm resistor
? This is based on pmalmsten's code found on the Arduino forum from 2007:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1176098434/0
*/
// Pins 2/3 used for Software serial
int irPin = 4; //Sensor pin 1 wired to Arduino's pin D4
int statLED = 0; //Toggle the status LED every time Power is pressed
int start_bit = 2200; //Start bit threshold (Microseconds)
int bin_1 = 1000; //Binary 1 threshold (Microseconds)
int bin_0 = 400; //Binary 0 threshold (Microseconds)
void setup() {
pinMode(statLED, OUTPUT);
digitalWrite(statLED, LOW);
pinMode(irPin, INPUT);
Serial.begin(9600);
Serial.println("IR/Serial Initialized: ");
}
void loop() {
int key = getIRKey(); //Fetch the key
if(key != 0) //Ignore keys that are zero
{
switch(key)
{
case 128: Serial.print("1"); break;
case 129: Serial.print("2"); break;
case 130: Serial.print("3"); break;
case 131: Serial.print("4"); break;
case 132: Serial.print("5"); break;
case 133: Serial.print("6"); break;
case 134: Serial.print("7"); break;
case 135: Serial.print("8"); break;
case 136: Serial.print("9"); break;
case 137: Serial.print("0"); break;
case 144: Serial.print("A"); break; // CH Up
case 145: Serial.print("B"); break; // CH Down
case 146: Serial.print("C"); break; // VOL Right
case 147: Serial.print("D"); break; // VOL Left
case 148: Serial.print("E"); break; // Mute
case 165: Serial.print("F"); break; // AV/TV
case 149: Serial.print("P"); // Power == MENU ACTIVE
//This toggles the statLED every time power button is hit
if(digitalRead(statLED) != 1)
digitalWrite(statLED, HIGH);
else
digitalWrite(statLED, LOW);
break;
//default: Serial.println(key); // for inspection of keycode
}
delay(400); // avoid double key logging (adjustable)
}
}
int getIRKey() {
int data[12];
int i;
while(pulseIn(irPin, LOW) < start_bit); //Wait for a start bit
for(i = 0 ; i < 11 ; i++)
data[i] = pulseIn(irPin, LOW); //Start measuring bits, I only want low pulses
for(i = 0 ; i < 11 ; i++) //Parse them
{
if(data[i] > bin_1) //is it a 1?
data[i] = 1;
else if(data[i] > bin_0) //is it a 0?
data[i] = 0;
else
return -1; //Flag the data as invalid; I don't know what it is! Return -1 on invalid data
}
int result = 0;
for(i = 0 ; i < 11 ; i++) //Convert data bits to integer
if(data[i] == 1) result |= (1<<i);
return result; //Return key number
}
