Direct Memory Access Controller

WIP functions for configuring and using the Direct Memory Access controller. More...

Data Structures
struct	gossamer_dma_job_t

Functions
void	dma_init (void)
	Initialize the DMA system.
bool	dma_configure (gossamer_dma_job_t *dmaJob, uint8_t peripheralTrigger, dma_trigger_action_t triggerAction, dma_configuration_flags_t flags)
	Configures a DMA job.
DmacDescriptor *	dma_add_descriptor (gossamer_dma_job_t *dmaJob, void *src, void *dst, uint32_t count, dma_beat_size_t size, dma_address_increment_t addressIncrement, dma_stepsize_t stepSize, dma_stepsel_t stepSel)
	Adds a descriptor to a DMA job.
bool	dma_start_job (gossamer_dma_job_t *dmaJob)

Detailed Description

WIP functions for configuring and using the Direct Memory Access controller.

Function Documentation

dma_add_descriptor()

DmacDescriptor * dma_add_descriptor	(	gossamer_dma_job_t *	dmaJob,
		void *	src,
		void *	dst,
		uint32_t	count,
		dma_beat_size_t	size,
		dma_address_increment_t	addressIncrement,
		dma_stepsize_t	stepSize,
		dma_stepsel_t	stepSel
	)

Adds a descriptor to a DMA job.

Adds a descriptor to a DMA job. You must configure the job before adding descriptors to it.

Parameters

dmaJob	A pointer to the DMA job. Must be previously configured with dma_configure().
src	The source address for this descriptor.
dst	The destination address for this descriptor.
count	The number of beats to transfer.
size	The beat size. One of: DMA_BEAT_SIZE_BYTE - One byte per beat DMA_BEAT_SIZE_HWORD - One half word (two bytes) per beat DMA_BEAT_SIZE_WORD - One word (four bytes) per beat
srcInc	Whether to increment the source address after each beat.
dstInc	Whether to increment the destination address after each beat.
stepSize	Address increment step size. One of: DMA_STEPSIZE_1 - Increment by 1 * beat size DMA_STEPSIZE_2 - Increment by 2 * beat size DMA_STEPSIZE_4 - Increment by 4 * beat size DMA_STEPSIZE_8 - ...you get the idea DMA_STEPSIZE_16 DMA_STEPSIZE_32 DMA_STEPSIZE_64 DMA_STEPSIZE_128
stepSel	Which address to increment by stepSize after each step. You can only have one: DMA_STEPSEL_SOURCE - Increment the source address after each step DMA_STEPSEL_DESTINATION - Increment the destination address after each step

dma_configure()

bool dma_configure	(	gossamer_dma_job_t *	dmaJob,
		uint8_t	peripheralTrigger,
		dma_trigger_action_t	triggerAction,
		dma_configuration_flags_t	flags
	)

Configures a DMA job.

Configures a DMA job with the given peripheral trigger and trigger action. You must configure the job before adding descriptors to it.

Parameters

dmaJob	A pointer to the DMA job to configure. This will be modified in place.
peripheralTrigger	The peripheral trigger to use for this job. These are defined in your microcontroller's data sheet, in the DMAC's register details section, under a headling like "Trigger Source"
triggerAction	The trigger action to use for this job. One of: DMA_TRIGGER_ACTION_BLOCK DMA_TRIGGER_ACTION_BEAT DMA_TRIGGER_ACTION_TRANSACTION
flags	A OR'ed bitmask of flags to use for this job. Available flags are: DMA_CONFIG_LOOP - Loop the job when it completes DMA_CONFIG_RUNSTDBY - Keep the job running in standby mode

dma_init()

void dma_init

(

void

)

Initialize the DMA system.

Sets up peripheral clocks and points the DMA controller at an empty list of descriptors.