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Clarify that DMA timer fraction must be <= 1 (#1723)

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Andrew Scheller 2024-06-21 20:29:47 +01:00 • committed by GitHub
parent 0e5cef3ffa
commit 5be87f1e22
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1 changed files with 3 additions and 1 deletions
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src/rp2_common/hardware_dma/include/hardware/dma.h
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@ -867,7 +867,8 @@ bool dma_timer_is_claimed(uint timer);
* \ingroup hardware_dma * \ingroup hardware_dma
* *
* The timer will run at the system_clock_freq * numerator / denominator, so this is the speed * The timer will run at the system_clock_freq * numerator / denominator, so this is the speed
* that data elements will be transferred at via a DMA channel using this timer as a DREQ * that data elements will be transferred at via a DMA channel using this timer as a DREQ. The
* multiplier must be less than or equal to one.
* *
* \param timer the dma timer * \param timer the dma timer
* \param numerator the fraction's numerator * \param numerator the fraction's numerator
@ -875,6 +876,7 @@ bool dma_timer_is_claimed(uint timer);
*/ */
static inline void dma_timer_set_fraction(uint timer, uint16_t numerator, uint16_t denominator) { static inline void dma_timer_set_fraction(uint timer, uint16_t numerator, uint16_t denominator) {
check_dma_timer_param(timer); check_dma_timer_param(timer);
invalid_params_if(DMA, numerator > denominator);
dma_hw->timer[timer] = (((uint32_t)numerator) << DMA_TIMER0_X_LSB) | (((uint32_t)denominator) << DMA_TIMER0_Y_LSB); dma_hw->timer[timer] = (((uint32_t)numerator) << DMA_TIMER0_X_LSB) | (((uint32_t)denominator) << DMA_TIMER0_Y_LSB);
} }