Configure the DMA for Capture TCC Channel 1

struct dma_resource capture_dma_resource;

struct dma_resource_config config;

dma_get_config_defaults(&config);

config.trigger_action = DMA_TRIGGER_ACTON_BEAT;
config.peripheral_trigger = CONF_CAPTURE_TRIGGER;

dma_allocate(&capture_dma_resource, &config);

1. Create a DMA transfer descriptor.

   COMPILER_ALIGNED(16) DmacDescriptor capture_dma_descriptor;
   

   Note: When multiple descriptors are linked, the linked item should never go out of scope before it is loaded (to DMA Write-Back memory section). In most cases, if more than one descriptors are used, they should be global except the very first one.

2. Create a DMA transfer descriptor struct.

3. Create a DMA transfer descriptor configuration structure, which can be filled out to adjust the configuration of a single DMA transfer.

   struct dma_descriptor_config descriptor_config;
   

4. Initialize the DMA transfer descriptor configuration struct with default values.

   dma_descriptor_get_config_defaults(&descriptor_config);
   

   Note: This should always be performed before using the configuration struct to ensure that all values are initialized to known default settings.
5. Adjust the DMA transfer descriptor configurations.

   descriptor_config.block_transfer_count = 3;
   descriptor_config.beat_size = DMA_BEAT_SIZE_HWORD;
   descriptor_config.step_selection = DMA_STEPSEL_SRC;
   descriptor_config.src_increment_enable = false;
   descriptor_config.source_address =
           (uint32_t)&CONF_PWM_MODULE->CC[CONF_TCC_CAPTURE_CHANNEL];
   descriptor_config.destination_address =
           (uint32_t)capture_values + sizeof(capture_values);
   

6. Create the DMA transfer descriptor with the given configuration.

   dma_descriptor_create(&capture_dma_descriptor, &descriptor_config);
   

1. Add the DMA transfer descriptor to the allocated DMA resource.

   dma_add_descriptor(&capture_dma_resource, &capture_dma_descriptor);
   dma_add_descriptor(&capture_dma_resource, &capture_dma_descriptor);
   

   Note: When adding multiple descriptors, the last added one is linked at the end of descriptor queue. If ringed list is needed, just add the first descriptor again to build the circle.
2. Start the DMA transfer job with the allocated DMA resource and transfer descriptor.

   dma_start_transfer_job(&capture_dma_resource);