Datasheet

1183
SAM3X / SAM3A [DATASHEET]
Atmel-11057C-ATARM-SAM3X-SAM3A-Datasheet_23-Mar-15
39.6.3.25 Host DMA Channel x Status Register
Name: UOTGHS_HSTDMASTATUSx [x=1..6]
Address: 0x400AC71C [1], 0x400AC72C [2], 0x400AC73C [3], 0x400AC74C [4], 0x400AC75C [5], 0x400AC76C [6],
0x400AC77C [7]
Access: Read-write
• CHANN_ENB: Channel Enable Status
0: if cleared, the DMA channel no longer transfers data, and may load the next descriptor if
UOTGHS_HSTDMACONTROLx.LDNXT_DSC bit is set.
When any transfer is ended either due to an elapsed byte count or a UOTGHS device initiated transfer end, this bit is auto-
matically reset.
1: if set, the DMA channel is currently enabled and transfers data upon request.
This bit is normally set or cleared by writing into UOTGHS_HSTDMACONTROLx.CHANN_ENB bit field either by software
or descriptor loading.
If a channel request is currently serviced when UOTGHS_HSTDMACONTROLx.CHANN_ENB bit is cleared, the DMA
FIFO buffer is drained until it is empty, then this status bit is cleared.
• CHANN_ACT: Channel Active Status
0: the DMA channel is no longer trying to source the packet data.
When a packet transfer is ended this bit is automatically reset.
1: the DMA channel is currently trying to source packet data, i.e. selected as the highest-priority requesting channel.
When a packet transfer cannot be completed due to an END_BF_ST, this flag stays set during the next channel descriptor
load (if any) and potentially until UOTGHS packet transfer completion, if allowed by the new descriptor.
• END_TR_ST: End of Channel Transfer Status
0: cleared automatically when read by software.
1: set by hardware when the last packet transfer is complete, if the UOTGHS device has ended the transfer.
Valid until CHANN_ENB flag is cleared at the end of the next buffer transfer.
• END_BF_ST: End of Channel Buffer Status
0: cleared automatically when read by software.
1: set by hardware when BUFF_COUNT count-down reaches zero.
Valid until CHANN_ENB flag is cleared at the end of the next buffer transfer.
31 30 29 28 27 26 25 24
BUFF_COUNT
23 22 21 20 19 18 17 16
BUFF_COUNT
15 14 13 12 11 10 9 8
––––––––
76543210
– DESC_LDST END_BF_ST END_TR_ST – – CHANN_ACT CHANN_ENB