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cpu/nrf5x_common: Implement timer_set()
The fallback implementation of timer_set() in `drivers/periph_common` is known to fail on short relative sets. This adds a robust implementation.
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@ -199,6 +199,11 @@ typedef struct {
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uint8_t irqn; /**< IRQ number of the timer device */
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} timer_conf_t;
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/**
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* @brief The nRF5x periph_timer implements timer_set()
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*/
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#define PERIPH_TIMER_PROVIDES_SET 1
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#ifndef DOXYGEN
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/**
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* @brief Override SPI mode values
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@ -117,6 +117,55 @@ int timer_set_absolute(tim_t tim, int chan, unsigned int value)
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return 0;
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}
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int timer_set(tim_t tim, int chan, unsigned int timeout)
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{
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static const uint32_t max_mask[] = {
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[TIMER_BITMODE_BITMODE_08Bit] = 0x000000ff,
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[TIMER_BITMODE_BITMODE_16Bit] = 0x0000ffff,
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[TIMER_BITMODE_BITMODE_24Bit] = 0x00ffffff,
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[TIMER_BITMODE_BITMODE_32Bit] = 0xffffffff,
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};
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/* see if channel is valid */
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if (chan >= timer_config[tim].channels) {
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return -1;
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}
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unsigned value = timer_read(tim) + timeout;
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unsigned irq_state = irq_disable();
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ctx[tim].flags |= (1 << chan);
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ctx[tim].is_periodic &= ~(1 << chan);
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dev(tim)->CC[chan] = value;
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/* clear spurious IRQs */
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dev(tim)->EVENTS_COMPARE[chan] = 0;
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(void)dev(tim)->EVENTS_COMPARE[chan];
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/* enable IRQ */
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dev(tim)->INTENSET = (TIMER_INTENSET_COMPARE0_Msk << chan);
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unsigned expires = value - timer_read(tim);
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expires &= max_mask[timer_config[tim].bitmode];
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if (expires > timeout) {
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/* timer already expired, check if IRQ flag is set */
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if (!dev(tim)->EVENTS_COMPARE[chan]) {
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/* timer has expired but IRQ flag is not set. The only way to not
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* wait *a full period* is now to set a new target to the next tick.
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* (Setting it to the current timer value will not trigger the IRQ
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* flag.) We briefly stop the timer to avoid a race, losing one
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* timer tick in accuracy. But that is better than a timer firing
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* a whole period too late */
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dev(tim)->TASKS_STOP = 1;
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dev(tim)->CC[chan] = timer_read(tim) + 1;
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dev(tim)->TASKS_START = 1;
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}
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}
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irq_restore(irq_state);
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return 0;
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}
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int timer_set_periodic(tim_t tim, int chan, unsigned int value, uint8_t flags)
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{
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/* see if channel is valid */
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