Type Alias rp2040_pac::dma::ch::ch_al1_ctrl::R

pub type R = R<CH_AL1_CTRL_SPEC>;

Register CH_AL1_CTRL reader

Aliased Type

struct R { /* private fields */ }

Implementations

impl R

pub fn en(&self) -> EN_R

Bit 0 - DMA Channel Enable.
When 1, the channel will respond to triggering events, which will cause it to become BUSY and start transferring data. When 0, the channel will ignore triggers, stop issuing transfers, and pause the current transfer sequence (i.e. BUSY will remain high if already high)

pub fn high_priority(&self) -> HIGH_PRIORITY_R

Bit 1 - HIGH_PRIORITY gives a channel preferential treatment in issue scheduling: in each scheduling round, all high priority channels are considered first, and then only a single low priority channel, before returning to the high priority channels.

This only affects the order in which the DMA schedules channels. The DMA’s bus priority is not changed. If the DMA is not saturated then a low priority channel will see no loss of throughput.

pub fn data_size(&self) -> DATA_SIZE_R

Bits 2:3 - Set the size of each bus transfer (byte/halfword/word). READ_ADDR and WRITE_ADDR advance by this amount (1/2/4 bytes) with each transfer.

pub fn incr_read(&self) -> INCR_READ_R

Bit 4 - If 1, the read address increments with each transfer. If 0, each read is directed to the same, initial address.

Generally this should be disabled for peripheral-to-memory transfers.

pub fn incr_write(&self) -> INCR_WRITE_R

Bit 5 - If 1, the write address increments with each transfer. If 0, each write is directed to the same, initial address.

Generally this should be disabled for memory-to-peripheral transfers.

pub fn ring_size(&self) -> RING_SIZE_R

Bits 6:9 - Size of address wrap region. If 0, don’t wrap. For values n > 0, only the lower n bits of the address will change. This wraps the address on a (1 << n) byte boundary, facilitating access to naturally-aligned ring buffers.

Ring sizes between 2 and 32768 bytes are possible. This can apply to either read or write addresses, based on value of RING_SEL.

pub fn ring_sel(&self) -> RING_SEL_R

Bit 10 - Select whether RING_SIZE applies to read or write addresses.
If 0, read addresses are wrapped on a (1 << RING_SIZE) boundary. If 1, write addresses are wrapped.

pub fn chain_to(&self) -> CHAIN_TO_R

Bits 11:14 - When this channel completes, it will trigger the channel indicated by CHAIN_TO. Disable by setting CHAIN_TO = (this channel).
Reset value is 0, which means for channels 1 and above the default will be to chain to channel 0 - set this field to avoid this behaviour.

pub fn treq_sel(&self) -> TREQ_SEL_R

Bits 15:20 - Select a Transfer Request signal.
The channel uses the transfer request signal to pace its data transfer rate. Sources for TREQ signals are internal (TIMERS) or external (DREQ, a Data Request from the system).
0x0 to 0x3a -> select DREQ n as TREQ

pub fn irq_quiet(&self) -> IRQ_QUIET_R

Bit 21 - In QUIET mode, the channel does not generate IRQs at the end of every transfer block. Instead, an IRQ is raised when NULL is written to a trigger register, indicating the end of a control block chain.

This reduces the number of interrupts to be serviced by the CPU when transferring a DMA chain of many small control blocks.

pub fn bswap(&self) -> BSWAP_R

Bit 22 - Apply byte-swap transformation to DMA data.
For byte data, this has no effect. For halfword data, the two bytes of each halfword are swapped. For word data, the four bytes of each word are swapped to reverse order.

pub fn sniff_en(&self) -> SNIFF_EN_R

Bit 23 - If 1, this channel’s data transfers are visible to the sniff hardware, and each transfer will advance the state of the checksum. This only applies if the sniff hardware is enabled, and has this channel selected.

This allows checksum to be enabled or disabled on a per-control- block basis.

pub fn busy(&self) -> BUSY_R

Bit 24 - This flag goes high when the channel starts a new transfer sequence, and low when the last transfer of that sequence completes. Clearing EN while BUSY is high pauses the channel, and BUSY will stay high while paused.

To terminate a sequence early (and clear the BUSY flag), see CHAN_ABORT.

pub fn write_error(&self) -> WRITE_ERROR_R

Bit 29 - If 1, the channel received a write bus error. Write one to clear.
WRITE_ADDR shows the approximate address where the bus error was encountered (will not be earlier, or more than 5 transfers later)

pub fn read_error(&self) -> READ_ERROR_R

Bit 30 - If 1, the channel received a read bus error. Write one to clear.
READ_ADDR shows the approximate address where the bus error was encountered (will not be earlier, or more than 3 transfers later)

pub fn ahb_error(&self) -> AHB_ERROR_R

Bit 31 - Logical OR of the READ_ERROR and WRITE_ERROR flags. The channel halts when it encounters any bus error, and always raises its channel IRQ flag.