Introduction: Throwduino Basic - Light-Sensing Flashing Throwie With 1 Added Part - Now With Morse Code
Throwies are great. They have a minimal parts count - 2 or 3 depending on whether you use a magnet - and produce a great effect. They are very cheap and easy but not highly efficient:
1) They are on all the time, so on average they waste half of their energy shining during the day.
2) A continuous light is not as visible as a flashing light. An interesting flash-pattern adds to the intrigue and can even convey information.
3) Their Duty cycle is too high - a duty cycle of 10-20% is more than sufficient to be both visible and much more efficient.
This is the first of what I hope to be 2-3 versions of microcontroller projects designed to be so cheap that they can be used as throwies. The plan is to make them more efficient and use that gain to provide a more exciting effect.
This is the "basic" version - it requires only one additional part, three blobs of solder and a few snips. And by magic* it can address all of the issues above. It's programmable using the Arduino IDE, hence "Throwduino".
On a per-hour basis it should even work out cheaper than a normal throwie. The cost analysis is in step 5.
Edit - Morse Code sketch now available - see last step.
- Now you can throw your own message of choice!
* not actually magic - see step 6.
Step 1: Parts
You need only 3 essential parts for this project:
An ultrabright blue, blue-green or white LED*
A CR2032 battery
An ATtiny25/45/85 AVR microcontroller.
Optionally, a rare earth magnet.
You will also need these tools:
Soldering iron & solder
Wire cutters
Tape
If you want to do this and don't want to bother programing the chip yourself, leave a message and I'll see if I can arrange a source of pre-programed chips.
Assuming that you need to program the ATtiny you will need:
Parts (unless you have a programing shield for ATTinys):
A DIP8 socket
6-pin 0.1" male header (or 4-pin if you use jumper leads below)
About 2x6 inches of essentially any insulated wire or 1-2 jumper leads (ideally two colours)
Or (alternative parts):
Solderless breadboard
Jumper wres
Tools:
An Arduino (an ISP programmer would also work)
PC with Arduino IDE & Arduino Tiny cores (more on this later)
Hot glue or epoxy advisable
* You could use an Red, Orange, Yellow or Yellow-Green LED but you would need to use a resistor or you would risk a brown-out on the controller and will get a very short lifetime. This adds 30% to the parts count but almost nothing to the price. 300-500 Ohms is not a bad place to start if you go this route. Maybe a little less for Yellow-Green.
Step 2: Build the Programming Parasite (micro Shield).
This step will assume that you need to program the ATtiny and are using an Arduino running the Arduino ISP as your programmer. If you have a pre-programed chip then skip to step 4. If you are using another programmer then you will need to adapt this slightly. Refer to the ATtiny datasheet for pin definitions etc.
If you already have a ATtiny programing shield or can hack your EMSL ATMega one like this: then you don't need to do this step - go on to the next step.
Equally, if you would rather program your ATTiny on a breadboard then there are plenty of tutorials for that, such as this or this. Note that these use the MIT ATtiny core which I have not tried in this project. However, you can use the same hardware setup with the Arduino Tiny cores.
Since we will be cutting the chip around, it will be a lot easier if we program it before we make the "throwie". To do this we will build the smallest programing board ever conceived* so that we can attach the chip to our Arduino for programing. It's a bit like a micro shield or perhaps an arduino parasite!
Firstly, take the 6-pin header and break it into a 4 and a 2. Identify pin 1 of the DIP-8 socket.
Now bend out pins 5-7 of the DIP-8 socket and solder the 4-pin header to bent pins 5-7 so that one pin of the header over-hangs past pin 5 of the socket.
Run a short wire from pin 1 of the socket to the over-hanging pin of the header.
Now connect the two remaining header pins to the VCC (pin 8) and Gnd (pin 4) connections of the DIP socket using around 4-6" wires. Using red for VCC and black for Gnd will help avoid chip-frying mistakes. If you have red/black jumper leads, just solder those to pins 8 and 4.
A spot of hot-glue or 5-minute epoxy to hold things tight would be a good plan at this point.
To use the programmer, insert your ATtiny into the DIP-8 (getting it the right way around - see picture 1) and plug the 4-pin header into your arduino at pins 10-13, so that the over-hanging pin of the programmer goes to pin D10. The two remaining pins on their fly-lead go into +5V and Gnd on the Arduino. Make sure you get them the right way around too! This is why coloured wires are a good plan for this.
You are now all rigged up for using your Arduino as an ISP for your ATtiny.
You may need to add a 10uf capacitor between Gnd and reset to avoid auto-reset issues.
All you need to do now is load the Arduino with the ISP sketch and install the Arduino Tiny cores (if you don't have that already). They can be found, along with instructions for installation, here.
If you want to watch what the ISP is doing, you can add LEDs and resistors between ground and each of pins 9, 8 and 7. They represent the programmer "heartbeat", error light and programing light respectively. In practice the flicker on the pin-13 LED tells you that it's working.
* This may be a slight exaggeration but it can't be very much so.
Step 3: Program the Chip
Having set up your programmer in the last step, load the Throwduino basic sketch to the IDE. It's pasted below and also attached.
threshold=(total>>5); // set threshold to average point (divide total by 128).
should probably be:
threshold=(total>>7); // set threshold to average point (divide total by 128).
It has worked for me as it was but this could cause problems with the light sensing. I will check and correct if needed.
If you would like to change the flash-sequence of your thowie then now is the time. Make sure that your code will fit in the memory of the chip you have. It's not likely to be an issue for anything bigger than an ATtiny25. The sketch below takes not much more than 1K. The code below displays the well-known "1-4-3" flash sequence. This may, of course, not be your thing, so hack-away.
The flash sequence is held in the array and simply holds a list of flash numbers. These are played with a short pause between each, followed by a 2-second pause before repeating. For example, for:
The throwie will flash once, pause, flash 4 times, pause, flash 3 times, pause for 2 seconds & repeat.
Once the sketch is ready, select ATtiny85 1Mz (or whichever ATtiny you are using) from the boards list in the IDE. If you don't select the correct board you may get a compile error (XXXX not defined in this scope). If you get this, check you have selected an ATtinyX5.
Hit "upload" in the IDE. The Arduino Tiny uses the Arduino ISP by default. You should see the pin13 LED on your Arduino flicker as the sketch is transferred.
How does the sketch work?
We have a few functions defined that do useful things and you might want to use in hacking:
void flash(byte) - flashes the LED "byte" times.
int lightLevel() - returns an int containing the light level measurement from the LED against the 2.56v internal ref.
void setup_watchdog(int) - sets the watchdog timer to value "int". There are 10 settings from 0 to 9 corresponding to 16, 32, 64, 128, 250, 500, 1000, 2000, 4000 & 8000 ms.
void system_sleep() - puts the system to sleep for the time set in the watchdog setup.
To start we poke at a few registers to set things up and minimise wasted power. Then in setup we flash 3 times and take 148 measurements of the light level. We throw away the first 20 and average the remaining 128. This sets the threshold by which we will judge when it is dark. We flash the LED that threshold number before carrying on. This is more for debugging than anything useful.
In the main loop we measure the light level and compare to the threshold value. If its under the value then we flash the LED by our pre-set pattern. If the light level is high then we sleep for 8 seconds (the longest that we can) before testing again.
My thanks to InsideGadgets for this article which formed the starting point for the sleep code. It's worth noting if you are using this that you need to reset the interrupt enable flag each time the WDT times out or the chip will reset next time.
Sketch (this should compile to around 1262 bytes):
// Throwduino basic
// Ugi 2012
// MIT license
// Written to run on ATtiny25/45/85 using Arduino Tiny core - http://code.google.com/p/arduino-tiny/
// Will not compile for other Arduinos (ATMega168, ATMega328 etc)
// Make sure you select the correct board before you compile.
// For Ref:
// ADC Pins:
// ADC1 = PB2
// ADC2 = PB4
// ADC3 = PB3
// If you just want to change the flash pattern, do it here.
// default is:
//
// const byte flashSeq[3]={1,4,3}; // Flash pattern
//
// This gives 1 flash, pause, four flashes, pause, three flashes, pause.
// If you just want a longer pause, use 0 for each 500ms.
// After the sequence, we wait for 2s before repeating.
const byte flashSeq[3]={1,4,3}; // Flash pattern. Edit this.
// how many entries in the flash pattern.
const byte seqLength =sizeof(flashSeq);
// Now let's make a throwie for that sequence....
const int LEDpin=4; // Although this is in a constant, there is a lot of direct port access
//I wouldn't try to change this without going throu' the whole code.
unsigned int threshold = 10; // We'll set this properly during setup
// This sets up some libs and definitions for use with the sleep timer
#include <avr/sleep.h>
#include <avr/wdt.h>
#ifndef cbi
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#endif
#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif
ISR(WDT_vect){ WDTCR|=B01000000;} // reset Watchdog Timer to Interrupt mode each time.
// Mess about with some registers to turn stuff off & set references.
void setup(){
ADCSRB&=B10111111; // disable comparitor
ACSR |=B10000000; // turn off power to comparitor
ADCSRA |=B10000000;// turn on ADC
DDRB&=B11100000; // set all to input
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // set PB3 low - this was for the testing phase. Can probably be dropped now.
PRR&=B11111110; // clear ADC disable bit in Power Reduction Reg
analogReference(6); // internal 2.56v reference with no bypass - INTERNAL2v56NB -
// Show we are awake:
flash(3); // Three flashes - we are up and running.
// Set the threshold for light sensing during first 40 seconds.
// We take 148 measurements, bin the first 20 and then average the next 128.
unsigned int total=0;
for (byte rep=0; rep<148; rep++){
int value=lightLevel();
// int value=10;
if(rep>19){
total+=value; // tatke total of 128 readings
}
//flash(value);
DDRB&=B11100000; // set all to input
setup_watchdog(4);
system_sleep();// sleep for quarter second
DDRB|=B00011010; // Set 1, 3 and 4 as output
PORTB&=B1110000; // Set all low
}
threshold=(total>>7); // set threshold to average point (divide total by 128).
flash(threshold); // This is mostly for debugging purposes.
}
//Main Loop
// We measure the light level. If it's low then we flash our sequence then sleep for 2s.
// If light level high, we sleep for 8s.
void loop(){
analogReference(6); // internal 2.56v reference with no bypass
// Measure light level and if it's low enough, display our flash sequence
if (lightLevel()<threshold){
for (byte sequence=0; sequence<seqLength; sequence++)
flash(flashSeq[sequence]);
// If we were flashing, we now sleep for 2s
DDRB&=B11100000; // set all to input
setup_watchdog(7);
system_sleep();// sleep for two seconds
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // PB3 low.
}
else{
// If we were not flashing then we sleep for 8s
DDRB&=B11100000; // set all to input
setup_watchdog(9);
system_sleep();// sleep for two seconds
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // PB3 low.
}
}// end main loop
// Measure light level by looking at voltage generated by LED connected to D4 (A2) on pin 3 of the chip.
// Set Output and low to start to discharge any charge buildup - not sure if we need this
int lightLevel(){
pinMode(LEDpin, OUTPUT);
digitalWrite (LEDpin,LOW);
delayMicroseconds(50);
pinMode(LEDpin, INPUT);
delayMicroseconds(100); // let it stabilise as an input again
unsigned int value = analogRead(A2);
return value;
}
// Flash routine - 70ms on, 250 ms off
// Repeat certain number of times and then pause 500ms
void flash(byte No){
pinMode(LEDpin, OUTPUT);
if(!No){// if we receive a zero, just pause.
DDRB&=B11100000; // set all to input
setup_watchdog(5);
system_sleep();// sleep for 500 ms
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // PB3 low.
}
// If we had a non-zero number of flashes, we'll make them now
for(byte rep=0; rep<No; rep++){
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // PB3 low.
PORTB|=B00010000; // PB4 High
//digitalWrite (LEDpin,HIGH);
delay(70);
PORTB&=B11101111; // PB4 low.
DDRB&=B11100000; // set all to input
//digitalWrite(LEDpin,LOW);
setup_watchdog(4); // WDT 3=128ms
system_sleep();
}
// Pause (sleep)
DDRB&=B11100000; // set all to input
setup_watchdog(5); // WDT 5 = 500ms
system_sleep();// sleep
DDRB|=B00011010; // Set 1 and 3 as output
PORTB&=B11110111; // PB3 low.
}
// Watchdog timer setup
// This is specific to the ATTiny85 (+ tiny45, & tiny25) and won't compile for ATMega328 etc.
// 0=16ms, 1=32ms,2=64ms,3=128ms,4=250ms,5=500ms
// 6=1 sec,7=2 sec, 8=4 sec, 9= 8sec
void setup_watchdog(int period) {
byte value;
if (period > 9) period=9;
value=period & B111;
if (period > 7) value|= (1<<5);
value|= (1<<WDCE);
MCUSR &= ~(1<<WDRF);
// start 4-clock-cycle timed sequence
WDTCR |= (1<<WDCE) | (1<<WDE);
// set new watchdog timeout value
WDTCR = value;
WDTCR |= _BV(WDIE);
}
// set system into the sleep state
// system wakes up when wtchdog is timed out
void system_sleep() {
cbi(ADCSRA,ADEN); // switch Analog to Digitalconverter OFF
set_sleep_mode(SLEEP_MODE_PWR_DOWN); // sleep mode is set here
sleep_enable();
sleep_mode(); // System sleeps here
sleep_disable(); // System continues execution here when watchdog timed out
sbi(ADCSRA,ADEN); // switch Analog to Digitalconverter ON
PRR&=B11111110; // clear ADC disable bit in Power Reduction Reg
}
Attachments
Step 4: Make Up the Throwie
Making up a Throwduino is only slightly more complex than a normal throwie, although you will probably need a soldering iron to make a decent job of it. Once you have made a couple they take less time to make than your soldering iron will take to warm up.
Program the chip before you cut it about - see the last two steps!
Remove the ATtiny from the programmer and find pin 1. Bend Ground pin 4 up above the chip. Now clip off pins 1, 2, 5, 6 & 7. If there's any chance that you might want to reprogram the chip then leave enough pin to solder onto later!
Take the LED and identify the +ve (anode) side. This usually has the longer lead and is away from the flat-spot on the lens. Solder pins 3 & 8 (which are the only pins that are still pointing down) to this leg of the LED, up fairly near the lens. Pin 3 should be closest to the LED lens. It's best to do this so the LED leg runs flush against the underside of the chip. Clip off the extra length on the pins of the chip.
Once soldered, clip a small section out of the LED leg between pins 3 and 8 to leave a gap (& no electrical connection) between.
Now solder the -ve (cathode) side of the LED (the side with the flat spot) to pin 4 that you bent up above the chip. Again, make it flush to the chip. Clip off the pin.
Now add the battery, being careful that the +ve side goes to the +ve of the LED and the under-side of the chip. Leave space so that the battery doesn't touch any part of the chip, ahtough the closest part to the battery should be pin 8 and that is connected to the battery anyway.
Tape around the battery and around the chip to hold them.
During the first 40 seconds of the throwie's life the light will flash three times and then go out. This is its sensing phase. After the flashes it will measure the average light level for the next 40 seconds.
You might like to put it somewhere dark (e.g. cupped in your hands) for some of this time to push the average down a bit so it only comes on when it's really dark.
After 40 seconds the LED will flash a few times and then go into "live" mode. It will now issue its flash sequence only when it senses darkness. Obviously, if you didn't get the threshold level right first time, just disconnect the battery and start again.
The light sensor can tell day from night and indoors from daylight* but it's not terribly sensitive.
If you are using a magnet, tape it on now.
You now have a Throwduino. With a fresh battery it should last a couple of weeks at least, although I haven't tested one to exhaustion yet so if you do so, please let me know.
Hope you enjoy them!
Ugi
* "But how?" I hear you cry - see step 6.
Step 5: Lifetime & Cost
There are a number of factors to take into account in assessing the lifetime of our throwie. Firstly, there is the current drawn by the LED.
Our friends over at Evil Mad Scientist were kind enough to conduct an analysis of the current drawn from a throwie over time. It can be found here:. If we are using the standard program, which runs at around 11% duty cycle then we would expect the lifetime to be 9-fold greater (9-18 weeks maybe).
However, we also have the overhead of running a microcontroller. At 1MHz and 3.3V, this would take around 2mA, which would potentially exhaust a CR2032 in as little as 4 days without any load. However, by setting the microcontroller to sleep during the "off" time for the LED, we can reduce the current to microamps during the off part of this cycle. I measured the sleep current to be 4.5uA, which is pretty minimal. This takes the average current down to around 11%, or 0.2mA. As the battery discharges, the lower voltage results in a still-lower current draw for the chip.
Measuring the actual current drawn, I am seeing about 4.5mA when the LED is on and 4.5 uA when it's off. This would give around 18 days from a 220mAh battery, but at 4.5mA, an LED would only last about 2 days and we know then last a week or two. Only time will tell how long we actually get.
As for the cost, a typical throwie (based on buying parts for 10) might cost:
Battery - 30p
LED - 15p
Magnet 40p
Total - 85p for a lifetime of around 1-2 weeks (42-85p per week).
For a Throwduino:
Battery - 30p
LED - 15p
Magnet - 40p
ATtiny85 (Mouser) - 60p
Total - £1.45 for a lifetime of 2, 4, 10 weeks, who-knows. (2-4 weeks would be £38-73p per week).
Obviously there is the extra time and the need for tools such as the PC, arduino and soldering iron but there is a good chance that if you are interested in microcontrolled throwies you may have these in any case.
If you don't want to program your own chips then I can probably find arrange a source of pre-programed ones.
Hopefully the addition of an ATtiny adds value at least in proportion to the additional cost.
Edit - 4 weeks later and the original throwduino is still flashing away. It survived weeks of constant rain in a totally exposed location but continues undaunted. I flashed away each night, even through pouring rain.
Further Edit - it lasted around 6 weeks. About half of that time it was flashing day and night. I think that may be due to using the higher 2.5V reference voltage, which might have dropped out when the battery became depleted. Using the 1.1V internal reference, I reckon you could get 8 weeks or more from one of these (because it could flash only at night).
Step 6: Magic
The "trick" to this project is that we are using a little known property of LEDs that I discovered here - they can act as photodiodes. We also rely on the fact that the ATtiny has an Analogue to Digital Converter (ADC) which we can press into use to measure this photodiode effect.
The trick to the 1-pin system is that Analog pin 2 in Arduino Tiny is the same as digital pin 4, so we can use the same LED as a sensor and an output. You could do the same with any analog pin on an Arduino but it would work our rather expensive!
When we start up the AVR we run the "setup" routine, which measures the voltage generated from light hitting the LED over 40 seconds, using code similar to that used during the "loop" routine. We measure 128 values and take the average of these as being the darkness threshold. This means we don't need to know the properties of the LED in advance. As long as it generates a signal we should be able to use it.
Any time that the power is removed or the chip is reset we will run that threshold sensing routine again. Therefore if the chip resets during the night for any reason it could result in a threshold that will rarely be crossed. Equally if it resets in bright sunshine then the light would probably stay on all the time. Life is fraught with hazard.
We could, possibly, write the threshold value to EEPROM but if we did that then we would only get one shot at making the battery connection. A further development would be to short two pins (e.g. connect pin 7 (PB2) to VCC) until we are happy with our threshold and then snip that pin to prevent further EEPROM writes. I may work on an update of that sort.
If you have any cunning ideas then I's love to hear them.
Now, to work no the next version - Throwduino RGB, I expect!
Step 7:
In this step you'll find the Morse Code ... erm.... code for Throwdurino.
The great thing about adding a microcontroller is that we can carry information. This sketch allows the same throwie to flash out a pre-programmed message in Morse Code. The initial threshold setting routine and light sensing method are the same as for the original sketch.
threshold=(total>>5); // set threshold to average point (divide total by 128).
should probably be:
threshold=(total>>7); // set threshold to average point (divide total by 128).
It has worked for me as it was but this could cause problems with the light sensing. I will check and correct if needed.
The timing of the Morse is not quite as fast as it should be - the pauses are much too long really - but I found the strict timing too fast for a novice to decode. Or too heavy on battery use. I think this is pretty clear to the novice Morse Coder.
To edit the message, find the line below at the top of the sketch:
and simply edit that as you require.
To minimise the length of the sketch, it only recognises capital letters. Everything else will be treated as a "space". Don't try to use more than 256 characters or it's likely to crash horribly.
The sketch is attached and pasted below. It should compile to around 1398 bytes
// Throwduino basic - Morse code edition!
// Ugi 2012
// MIT license
// Written to run on ATtiny25/45/85 using Arduino Tiny core - http://code.google.com/p/arduino-tiny/
// Will not compile for other Arduinos (ATMega168, ATMega328 etc)
// Make sure you select the correct board before you compile.
// For Ref:
// ADC Pins:
// ADC1 = PB2
// ADC2 = PB4
// ADC3 = PB3
// If you just want to change the flash pattern, do it here.
// default is:
//
//const char flashSeq[]={"DARK HERE ISNT IT"}; // Morse message. Edit this.
//
// Edit the message with UPPER CASE CHARACTERS ONLY.
// Anything else will come out as a 1s delay.
// After the sequence, we wait for 2s before repeating.
const char flashSeq[]={"DARK HERE ISNT IT"}; // Morse message. Edit this.
const byte seqLength =(sizeof(flashSeq)-1);
// Morse code encoding
// Stored as one byte per letter.
// High 5 bits are 1 for - and 0 for beginning with LSB of those high-5..
// Low 3 bits give number of flashes (dots + dashes).
// Morse allows for 5 flashes (for numbers) but letters require 4 maximum.
// This format could thus be used for numbers as well but I have not implemented that.
const byte morse[26]={
B00010010, //a
B00001100, //b
B00101100, //c
B00001011, //d
B00000001, //e
B00100100, //f
B00011011, //g
B00000100, //h
B00000010, //i
B01110100, //j
B00101011, //k
B00010100, //l
B00011010, //m
B00001010, //n
B00111011, //o
B00110100, //p
B01011100, //q
B00010011, //r
B00000011, //s
B00001001, //t
B00100011, //u
B01000100, //v
B00110011, //w
B01001100, //x
B01101100, //y
B00011100, //z
};
// Now let's make a throwie for that sequence....
const int LEDpin=4; // Although this is in a constant, there is a lot of direct port access
//I wouldn't try to change this without going throu' the whole code.
unsigned int threshold = 10; // We'll set this properly during setup
// This sets up some libs and definitions for use with the sleep timer
#include <avr/sleep.h>
#include <avr/wdt.h>
#ifndef cbi
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#endif
#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif
ISR(WDT_vect){ WDTCR|=B01000000;} // reset Watchdog Timer to Interrupt mode each time.
// Mess about with some registers to turn stuff off & set references.
void setup(){
ADCSRB&=B10111111; // disable comparitor
ACSR |=B10000000; // turn off power to comparitor
ADCSRA |=B10000000;// turn on ADC
DDRB&=B11100000; // set all to input
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // set PB3 low - this was for the testing phase. Can probably be dropped now.
PRR&=B11111110; // clear ADC disable bit in Power Reduction Reg
analogReference(6); // internal 2.56v reference with no bypass - INTERNAL2v56NB -
// Show we are awake:
flash(3); // Three flashes - we are up and running.
// Set the threshold for light sensing during first 40 seconds.
// We take 148 measurements, bin the first 20 and then average the next 128.
unsigned int total=0;
for (byte rep=0; rep<148; rep++){
int value=lightLevel();
// int value=10;
if(rep>19){
total+=value; // tatke total of 128 readings
}
//flash(value);
pause(4);// was pause(4)
DDRB|=B00011010; // Set 1, 3 and 4 as output
PORTB&=B1110000; // Set all low
}
threshold=(total>>7); // set threshold to average point (divide total by 128).
//flash(threshold); // This is mostly for debugging purposes.
}
//Main Loop
// We measure the light level. If it's low then we flash our sequence then sleep for 2s.
// If light level high, we sleep for 8s.
void loop(){
analogReference(6); // internal 2.56v reference with no bypass
// Measure light level and if it's low enough, display our flash sequence
if (lightLevel()<threshold){
flashMorse();
// If we were flashing, we now sleep for 4s
pause(8);
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // PB3 low.
}
else{
// If we were not flashing then we sleep for 8s
pause(9);
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // PB3 low.
}
}// end main loop
// Measure light level by looking at voltage generated by LED connected to D4 (A2) on pin 3 of the chip.
// Set Output and low to start to discharge any charge buildup - not sure if we need this
int lightLevel(){
pinMode(LEDpin, OUTPUT);
digitalWrite (LEDpin,LOW);
delayMicroseconds(50);
pinMode(LEDpin, INPUT);
delayMicroseconds(100); // let it stabilise as an input again
unsigned int value = analogRead(A2);
return value;
}
// Flash routine - 70ms on, 250 ms off
// Repeat certain number of times and then pause 500ms
void flash(byte No){
pinMode(LEDpin, OUTPUT);
if(!No){// if we receive a zero, just pause.
pause(5);
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // PB3 low.
}
// If we had a non-zero number of flashes, we'll make them now
for(byte rep=0; rep<No; rep++){
flashDot(70);
}
// Pause (sleep)
pause(5);
DDRB|=B00011010; // Set 1 and 3 as output
PORTB&=B11110111; // PB3 low.
}
void pause(byte time){
DDRB&=B11100000; // set all to input
setup_watchdog(time); // set up wait period
system_sleep();// sleep
}
void flashMorse(){
for(byte rep=0; rep<seqLength; rep++){
byte index=0;
if(flashSeq[rep]<65 || flashSeq[rep]>90)index=0;
else index=flashSeq[rep]-64;
if(!index) pause(6);
else {
byte dotdash = morse[index-1]>>3; // put just sequence part (5 bits) into dotdash
// Dots and dashes according to sequence encoded in morse[]
for(byte flashes=0; flashes<((morse[(index-1)]&B111)); flashes++){
if(dotdash&1)flashDot(160); // if LSB is 1 then display a dash
else flashDot(40); // otherwise it's a dot
pause(4); // pause between flashes - 256ms
dotdash>>=1; // roll along to the next bit
}
pause(5); // End of word pause 0.5s
}
}
}
// flash the LED for time (<256 ms) and pause for 250ms.
void flashDot(byte time){
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // PB3 low.
PORTB|=B00010000; // PB4 High
delay(time);
PORTB&=B11101111; // PB4 low.
pause(4);
}
// Watchdog timer setup
// This is specific to the ATTiny85 (+ tiny45, & tiny25) and won't compile for ATMega328 etc.
// 0=16ms, 1=32ms,2=64ms,3=128ms,4=250ms,5=500ms
// 6=1 sec,7=2 sec, 8=4 sec, 9= 8sec
void setup_watchdog(int period) {
byte value;
if (period > 9) period=9;
value=period & B111;
if (period > 7) value|= (1<<5);
value|= (1<<WDCE);
MCUSR &= ~(1<<WDRF);
// start 4-clock-cycle timed sequence
WDTCR |= (1<<WDCE) | (1<<WDE);
// set new watchdog timeout value
WDTCR = value;
WDTCR |= _BV(WDIE);
}
// set system into the sleep state
// system wakes up when wtchdog is timed out
void system_sleep() {
cbi(ADCSRA,ADEN); // switch Analog to Digitalconverter OFF
set_sleep_mode(SLEEP_MODE_PWR_DOWN); // sleep mode is set here
sleep_enable();
sleep_mode(); // System sleeps here
sleep_disable(); // System continues execution here when watchdog timed out
sbi(ADCSRA,ADEN); // switch Analog to Digitalconverter ON
PRR&=B11111110; // clear ADC disable bit in Power Reduction Reg
}
// Ugi 2012
// MIT license
// Written to run on ATtiny25/45/85 using Arduino Tiny core - http://code.google.com/p/arduino-tiny/
// Will not compile for other Arduinos (ATMega168, ATMega328 etc)
// Make sure you select the correct board before you compile.
// For Ref:
// ADC Pins:
// ADC1 = PB2
// ADC2 = PB4
// ADC3 = PB3
// If you just want to change the flash pattern, do it here.
// default is:
//
//const char flashSeq[]={"DARK HERE ISNT IT"}; // Morse message. Edit this.
//
// Edit the message with UPPER CASE CHARACTERS ONLY.
// Anything else will come out as a 1s delay.
// After the sequence, we wait for 4s before repeating.
const char flashSeq[]={"DARK HERE ISNT IT"}; // Morse message. Edit this.
const byte seqLength =(sizeof(flashSeq)-1);
// Morse code encoding
// Stored as one byte per letter.
// High 5 bits are 1 for - and 0 for beginning with LSB of those high-5..
// Low 3 bits give number of flashes (dots + dashes).
//Morse allows for 5 flashes (for numbers) but letters require 4 maximum.
//This format could thus be used for numbers as well but I have not implemented that.
const byte morse[26]={
B00010010, //a
B00001100, //b
B00101100, //c
B00001011, //d
B00000001, //e
B00100100, //f
B00011011, //g
B00000100, //h
B00000010, //i
B01110100, //j
B00101011, //k
B00010100, //l
B00011010, //m
B00001010, //n
B00111011, //o
B00110100, //p
B01011100, //q
B00010011, //r
B00000011, //s
B00001001, //t
B00100011, //u
B01000100, //v
B00110011, //w
B01001100, //x
B01101100, //y
B00011100, //z
};
// Now let's make a throwie for that sequence....
const int LEDpin=4; // Although this is in a constant, there is a lot of direct port access
//I wouldn't try to change this without going throu' the whole code.
unsigned int threshold = 10; // We'll set this properly during setup
// This sets up some libs and definitions for use with the sleep timer
#include
#include
#ifndef cbi
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#endif
#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif
ISR(WDT_vect){ WDTCR|=B01000000;} // reset Watchdog Timer to Interrupt mode each time.
// Mess about with some registers to turn stuff off & set references.
void setup(){
ADCSRB&=B10111111; // disable comparitor
ACSR |=B10000000; // turn off power to comparitor
ADCSRA |=B10000000;// turn on ADC
DDRB&=B11100000; // set all to input
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // set PB3 low - this was for the testing phase. Can probably be dropped now.
PRR&=B11111110; // clear ADC disable bit in Power Reduction Reg
analogReference(6); // internal 2.56v reference with no bypass - INTERNAL2v56NB -
// Show we are awake:
flash(3); // Three flashes - we are up and running.
// Set the threshold for light sensing during first 40 seconds.
// We take 148 measurements, bin the first 20 and then average the next 128.
unsigned int total=0;
for (byte rep=0; rep<148; rep++){
int value=lightLevel();
// int value=10;
if(rep>19){
total+=value; // tatke total of 128 readings
}
//flash(value);
pause(4);// was pause(4)
DDRB|=B00011010; // Set 1, 3 and 4 as output
PORTB&=B1110000; // Set all low
}
threshold=(total>>5); // set threshold to average point (divide total by 128).
//flash(threshold); // This is mostly for debugging purposes.
}
//Main Loop
// We measure the light level. If it's low then we flash our sequence then sleep for 2s.
// If light level high, we sleep for 8s.
void loop(){
analogReference(6); // internal 2.56v reference with no bypass
// Measure light level and if it's low enough, display our flash sequence
if (lightLevel()
flashMorse();
// If we were flashing, we now sleep for 4s
pause(8);
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // PB3 low.
}
else{
// If we were not flashing then we sleep for 8s
pause(9);
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // PB3 low.
}
}// end main loop
// Measure light level by looking at voltage generated by LED connected to D4 (A2) on pin 3 of the chip.
// Set Output and low to start to discharge any charge buildup - not sure if we need this
int lightLevel(){
pinMode(LEDpin, OUTPUT);
digitalWrite (LEDpin,LOW);
delayMicroseconds(50);
pinMode(LEDpin, INPUT);
delayMicroseconds(100); // let it stabilise as an input again
unsigned int value = analogRead(A2);
return value;
}
// Flash routine - 70ms on, 250 ms off
// Repeat certain number of times and then pause 500ms
void flash(byte No){
pinMode(LEDpin, OUTPUT);
if(!No){// if we receive a zero, just pause.
pause(5);
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // PB3 low.
}
// If we had a non-zero number of flashes, we'll make them now
for(byte rep=0; rep flashDot(70);
}
// Pause (sleep)
pause(5);
DDRB|=B00011010; // Set 1 and 3 as output
PORTB&=B11110111; // PB3 low.
}
void pause(byte time){
DDRB&=B11100000; // set all to input
setup_watchdog(time); // set up wait period
system_sleep();// sleep
}
void flashMorse(){
for(byte rep=0; rep byte index=0;
if(flashSeq[rep]<65 || flashSeq[rep]>90)index=0;
else index=flashSeq[rep]-64;
if(!index) pause(6);
else {
byte dotdash = morse[index-1]>>3; // put just sequence part (5 bits) into dotdash
// Dots and dashes according to sequence encoded in morse[]
for(byte flashes=0; flashes<((morse[(index-1)]&B111)); flashes++){
if(dotdash&1)flashDot(160); // if LSB is 1 then display a dash
else flashDot(40); // otherwise it's a dot
pause(5); // pause between flashes - 256ms
dotdash>>=1; // roll along to the next bit
}
pause(6); // End of word pause 1 s
}
}
}
// flash the LED for time (<256 ms) and pause for 250ms.
void flashDot(byte time){
DDRB|=B00011010; // Set 1,3 and 4 as output
PORTB&=B11110111; // PB3 low.
PORTB|=B00010000; // PB4 High
delay(time);
PORTB&=B11101111; // PB4 low.
pause(4);
}
// Watchdog timer setup
// This is specific to the ATTiny85 (+ tiny45, & tiny25) and won't compile for ATMega328 etc.
// 0=16ms, 1=32ms,2=64ms,3=128ms,4=250ms,5=500ms
// 6=1 sec,7=2 sec, 8=4 sec, 9= 8sec
void setup_watchdog(int period) {
byte value;
if (period > 9) period=9;
value=period & B111;
if (period > 7) value|= (1<<5);
value|= (1<
MCUSR &= ~(1<
// start 4-clock-cycle timed sequence
WDTCR |= (1< // set new watchdog timeout value
WDTCR = value;
WDTCR |= _BV(WDIE);
}
// set system into the sleep state
// system wakes up when wtchdog is timed out
void system_sleep() {
cbi(ADCSRA,ADEN); // switch Analog to Digitalconverter OFF
set_sleep_mode(SLEEP_MODE_PWR_DOWN); // sleep mode is set here
sleep_enable();
sleep_mode(); // System sleeps here
sleep_disable(); // System continues execution here when watchdog timed out
sbi(ADCSRA,ADEN); // switch Analog to Digitalconverter ON
PRR&=B11111110; // clear ADC disable bit in Power Reduction Reg
}
Attachments
Finalist in the
Pocket-Sized Contest
