Guy please help with this code i made the part con count 0/999 but i don't know how to make 999/0
Por favor ayudenme, ya hice la parte de codigo que va de 0 hasta 999 pero ni idea como hacer el contador de 999 a 0 descendete
byte lectura=B0;
unsigned int contadorInterruptor=0,contadorAnodos=0,contadorNumero=0;
byte numero=0,bases=0;
const byte deco7seg[10]={B1000000,B1111001,B100100,B110000,B11001,B10010,B10,B1111000,B0,B10000};
const byte anodos[3]={B110,B101,B011};
int infoDisplays[3]={0,0,0};
void setup(void) {
// put your setup code here, to run once:
DDRL=B111;
DDRC=B1111111;
PORTL=B11100;
}
void timers(void){
contadorNumero++;
contadorInterruptor++;
contadorAnodos++;
delay(1);
}
void loop(void) {
// put your main code here, to run repeatedly:
PORTL=B111;
if(contadorNumero==60){
contadorNumero=0;
infoDisplays[0]++;
if (infoDisplays[0]==10)
{
infoDisplays[0]=0;
infoDisplays[1]++;
if(infoDisplays[1]==10){
infoDisplays[1]=0;
infoDisplays[2]++;
if(infoDisplays[2]==10){
infoDisplays[2]=0;
}
}
}
}
if(contadorInterruptor==200){
contadorInterruptor=0;
lectura=(PINL&B11100)>>3;
}
if(contadorAnodos==8)
{
contadorAnodos=0;
PORTL=anodos[bases];
PORTC=deco7seg[infoDisplays[bases]];
bases++;
if (bases==3){ bases=0;}
}
timers();
}
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I think that you have learned how to subtract at school 
To count down, start with all digits set to 9. Then subtract 1 from the lowest digit, and if the result is beyond 0, set it to 0 and continue to subtract 1 from the next digit (borrow).
It may be much easier to use an int variable for the value, which you can increment and decrement easily. Much easier than your BCD representation of the counter. Then write a function to decode that binary value into decimal digits, for output to the display.