DMA programming examples

AN3117

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Doc ID 16846 Rev 4

4.4.2

DMA transfer example in Wait for interrupt (WFI) mode

This example uses the DMA peripheral to transfer data in exactly the same way as the WFE

example. The difference is that the treatment (LED activation/deactivation depending on the

data in the RAM buffer) is performed by the DMA transfer complete interrupt routine, without

returning to the main program.

The code for this example is provided in the STM8L05x/STM8L15x/STM8L16x/STM8AL31x/

STM8AL3Lx standard peripheral library package.

4.5

DMA transfer example with TIM1 in Burst mode

Figure 7.

DMA transfer example with TIM1 in Burst mode

This example uses the DMA peripheral in Burst mode to transfer data from the RAM

memory to TIM1. TIM1 is configured in pulse width modulation (PWM) output mode and

DMA channel 2 is configured to transfer data from the RAM memory to the TIM1 registers

(TIM1_PSCRH, TIM1_PSCRL, TIM1_ARRH, TIM1_ARRL, TIM1_RCR, TIM1_CCR1H,

TIM1_CCR1L). The goal of this data transfer is to update simultaneously TIM1 channel 1

frequency and duty cycle when an EXTI event triggered by the key button occurs.

The code for this example is provided in the STM8L05x/STM8L15x/STM8L16x/STM8AL31x/

STM8AL3Lx standard peripheral library package.

TIM1

DMA1

Channel 2

TIM1_DMAR

DMA

source

System

bus

Program bus

DMA

destination

ai17422

Data CR1

DMA1 bus

Data CR2

Data SMCR

Data ETR

Data OISR

TIM1_CR1

TIM1_CR2

TIM1_SMCR

TIM1_ETR

...

TIM1_OISR