512 bytes of flash, running the classic "random number generator" (increment the number, but do it so quickly no one could possibly control it.)
/*
* ATTiny4Test.c
*
* Created: 1/16/2014 8:34:30 PM
* Author: Joe
*/
#include <avr/io.h>
// pin 1 attiny4 pb0 -> pin 4 LTM-8647AP serial data
// pin 3 attiny4 pb1 -> pin 5 LTM-8647AP clock
// pin 4 attiny4 pb2 -> switch with pullup to 5V, depressed = 0V.
//
// Datasheet for LTM-8647AP is http://optoelectronics.liteon.com/upload/download/DS-30-98-355/P_100_M8647AG.pdf
uint8_t ConvertNumToDisplayBitmap(uint8_t dig)
{
uint8_t cb = 0;
// segment A - bit 0
if (dig==0 || dig==2 || dig==3 || dig==5 || dig==6 || dig==7 || dig==8 || dig==9)
cb |= 1;
// segment B - bit 1
if (dig==0 || dig==1 || dig==2 || dig==3 || dig==4 || dig==7 || dig==8 || dig==9)
cb |= 2;
// segment C - bit 2
if (dig==0 || dig==1 || dig==3 || dig==4 || dig==5 || dig==6 || dig==7 || dig==8 || dig==9)
cb |= 4;
// segment D - bit 3
if (dig==0 || dig==2 || dig==3 || dig==5 || dig==6 || dig==8 || dig==9)
cb |= 8;
// segment E - bit 4
if (dig==0 || dig==2 || dig==6 || dig==8)
cb |= 16;
// segment F - bit 5
if (dig==0 || dig==4 || dig==5 || dig==6 || dig==8 || dig==9)
cb |= 32;
// segment G - bit 6 and 7. Segment G is divided into two segments on this 14 segment display.
if (dig==2 || dig==3 || dig==4 || dig==5 || dig==6 || dig==8 || dig==9)
cb |= 192;
return cb;
}
int main(void)
{
CCP = 0xD8; // unprotect prescaler
CLKPSR &= 0b11110110; // set prescaler to 32 (on a 12mhz clock = 375Khz, to keep time with slower serial LCD chip)
DDRB |= 0b00000011; // ports B0, B1 output, to LCD chip
DDRB &= 0b11111011; // port B2 input, to produce "random" number
uint8_t i = 0;
uint8_t curnum = 0;
while(1)
{
PORTB &= 0b11111101; // clock low
PORTB |= 0b00000001; // data high
PORTB |= 0b00000010; // clock high
if ((PINB & 4) == 0)
curnum ++;
if (curnum > 99)
curnum = 0;
uint8_t lsd = curnum%10; // least significant, rightmost digit, digit "2" on display.
uint8_t msd = curnum/10; // most significant, leftmost digit, digit "1" on display.
uint8_t cb = 0; // current digit 0-9.
cb = ConvertNumToDisplayBitmap(lsd); // get least significant, rightmost digit, digit "2" on display.
for (i=0;i<8;i++)
{
PORTB &= 0b11111101; // clock low
if ((cb & (1<<i)) == 0)
PORTB &= 0b11111110; // data low
else
PORTB |= 0b00000001; // data high
PORTB |= 0b00000010; // clock high
}
PORTB &= 0b11111110; // data low
// pad it with zeros for segments we don't use.
for (i=0;i<6;i++)
{
PORTB &= 0b11111101; // clock low
PORTB |= 0b00000010; // clock high
}
cb = ConvertNumToDisplayBitmap(msd); // get most significant, leftmost digit, digit "1" on display.
for (i=0;i<8;i++)
{
PORTB &= 0b11111101; // clock low
if ((cb & (1<<i)) == 0)
PORTB &= 0b11111110; // data low
else
PORTB |= 0b00000001; // data high
PORTB |= 0b00000010; // clock high
}
PORTB &= 0b11111110; // data low
// pad it with zeros for segments we don't use plus the 4 bonus outputs.
for (i=0;i<13;i++)
{
PORTB &= 0b11111101; // clock low
PORTB |= 0b00000010; // clock high
}
}
}
I have a couple of ATTiny10s sitting in my pile of bits somewhere that I have been meaning to do something with but have never gotten around to it.