LPC2129 timer0

Do you mean that "I need to control the timing for A , B and C, all using timer0, how to use an single timer for those things".

If so, how about use several counters in the timer0 ISR?

void Timer0Handler (void) __irq
{
    timer0_counter++;

    if ( timer_A != 0 )
        timer_A--;

    if ( timer_B != 0 )
        timer_B--;

    if ( timer_C != 0 )
        timer_C--;

    T0IR = 1;                   /* clear interrupt flag */
    VICVectAddr = 0;            /* Acknowledge Interrupt */
}

In your application, check if the counters of A/B/C become 0; if it is 0 "already", then do something and reset the counter.

The disadvantage is, it is not precise. Maybe someone else knows a better way. :)

Do you mean that "I need to control the timing for A , B and C, all using timer0, how to use an single timer for those things".

If so, how about use several counters in the timer0 ISR?

void Timer0Handler (void) __irq
{
    timer0_counter++;

    if ( timer_A != 0 )
        timer_A--;

    if ( timer_B != 0 )
        timer_B--;

    if ( timer_C != 0 )
        timer_C--;

    T0IR = 1;                   /* clear interrupt flag */
    VICVectAddr = 0;            /* Acknowledge Interrupt */
}

In your application, check if the counters of A/B/C become 0; if it is 0 "already", then do something and reset the counter.

The disadvantage is, it is not precise. Maybe someone else knows a better way. :)

Note that each timer has multiple compare/match registers, so it can generate interrupts or toggle a pin at different phases of the countdown.