Yep there is an internal temp sensor on the attiny85 - here is some example code for it - it logs the temp to the internal EEPROM once per second. If you plug it in a short pin 5 to ground it will type out (as if a keyboard) all of the logged temps - I call it the "SimplestTempLogger"
<code>
#include "DigiKeyboard.h"
#include <EEPROM.h>
int tempOffset = 10; //set the offset here after calibrating against known source
unsigned int logInterval = 120; //log a temperature every X seconds
unsigned int addressLimit = 511;
unsigned int address = 0;
unsigned int mode = 1;
void setup(void)
{
pinMode(5, INPUT);
pinMode(1, OUTPUT);
digitalWrite(5,HIGH);
int modeInput = digitalRead(5);
if(modeInput == LOW){
mode = 0;
}
if(mode == 1){
analogReference(INTERNAL1V1);
}
}
void ledState(int state){
digitalWrite(1,state);
}
void readTemp(){
ledState(HIGH);
int returned = EEPROM.read(address);
if(returned == 255){ //stop when we hit 255 - which means we got it all
address = addressLimit+1;
return;
}
address++;
// this is generally not necessary but with some older systems it seems to
// prevent missing the first character after a delay:
DigiKeyboard.sendKeyStroke(0);
// Type out this string letter by letter on the computer (assumes US-style
// keyboard)
DigiKeyboard.println(returned);
// It's better to use DigiKeyboard.delay() over the regular Arduino delay()
// if doing keyboard stuff because it keeps talking to the computer to make
// sure the computer knows the keyboard is alive and connected
DigiKeyboard.delay(15);
ledState(LOW);
DigiKeyboard.delay(15);
}
void writeTemp(){
ledState(HIGH);
int raw = analogRead(A0+15);
/* Original code used a 13 Cdeg adjustment. But based on my results, I didn't seem to need it. */
// raw -= 13; // raw adjust = kelvin
//int in_c = raw - 273; // celcius
//in_c = round(in_c);
int in_f = ((raw - 273)*1.
+32; // temp in f
in_f = round(in_f)+tempOffset;
EEPROM.write(address, 255);//set next block to 255 so we know where it stopped
EEPROM.write(address, in_f);
address++; //increment address
//delay until next log interval but blink while delaying
int i =0;
while (i<logInterval){
ledState(HIGH);
DigiKeyboard.delay(500);
ledState(LOW);
DigiKeyboard.delay(500);
i++;
}
}
void loop(){
if(address>addressLimit){
ledState(LOW);
DigiKeyboard.delay(1000);
}
else if(mode ==1){
writeTemp();
}
else if(mode ==0){
readTemp();
}
}
</code>
