Expand description
DMA Channel 0 Control and Status
Structs§
- CH_
CTRL_ TRIG_ SPEC - DMA Channel 0 Control and Status
Enums§
- DATA_
SIZE_ A - 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.
- RING_
SIZE_ A - 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.
- TREQ_
SEL_ A - 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
Type Aliases§
- AHB_
ERROR_ R - Field
AHB_ERRORreader - 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. - BSWAP_R
- Field
BSWAPreader - 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. - BSWAP_W
- Field
BSWAPwriter - 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. - BUSY_R
- Field
BUSYreader - 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. - CHAIN_
TO_ R - Field
CHAIN_TOreader - 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. - CHAIN_
TO_ W - Field
CHAIN_TOwriter - 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. - DATA_
SIZE_ R - Field
DATA_SIZEreader - 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. - DATA_
SIZE_ W - Field
DATA_SIZEwriter - 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. - EN_R
- Field
ENreader - 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) - EN_W
- Field
ENwriter - 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) - HIGH_
PRIORITY_ R - Field
HIGH_PRIORITYreader - 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. - HIGH_
PRIORITY_ W - Field
HIGH_PRIORITYwriter - 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. - INCR_
READ_ R - Field
INCR_READreader - If 1, the read address increments with each transfer. If 0, each read is directed to the same, initial address. - INCR_
READ_ W - Field
INCR_READwriter - If 1, the read address increments with each transfer. If 0, each read is directed to the same, initial address. - INCR_
WRITE_ R - Field
INCR_WRITEreader - If 1, the write address increments with each transfer. If 0, each write is directed to the same, initial address. - INCR_
WRITE_ W - Field
INCR_WRITEwriter - If 1, the write address increments with each transfer. If 0, each write is directed to the same, initial address. - IRQ_
QUIET_ R - Field
IRQ_QUIETreader - 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. - IRQ_
QUIET_ W - Field
IRQ_QUIETwriter - 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. - R
- Register
CH_CTRL_TRIGreader - READ_
ERROR_ R - Field
READ_ERRORreader - 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) - READ_
ERROR_ W - Field
READ_ERRORwriter - 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) - RING_
SEL_ R - Field
RING_SELreader - 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. - RING_
SEL_ W - Field
RING_SELwriter - 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. - RING_
SIZE_ R - Field
RING_SIZEreader - 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_
SIZE_ W - Field
RING_SIZEwriter - 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. - SNIFF_
EN_ R - Field
SNIFF_ENreader - 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. - SNIFF_
EN_ W - Field
SNIFF_ENwriter - 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. - TREQ_
SEL_ R - Field
TREQ_SELreader - 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 - TREQ_
SEL_ W - Field
TREQ_SELwriter - 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 - W
- Register
CH_CTRL_TRIGwriter - WRITE_
ERROR_ R - Field
WRITE_ERRORreader - 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) - WRITE_
ERROR_ W - Field
WRITE_ERRORwriter - 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)