![ARTERY AT32F435 Series Скачать руководство пользователя страница 623](http://html1.mh-extra.com/html/artery/at32f435-series/at32f435-series_reference-manual_2977592623.webp)
AT32F435/437
Series Reference Manual
2022.11.11
Page 623
Rev 2.03
Otherwise, Rx has priority over Tx.
Bit 0
SWR
0x1
rw
Software Reset
When this bit is set, the MAC DMA controller resets all
internal registers and MAC logic. This bit is automatically
cleared after all reset operations have been completed.
26.3.22 Ethernet DMA transmit poll demand register
(EMAC_DMATPD)
The EMAC_DMATPD register enables the Tx DMA to check whether or not the current descriptor is
owned by the DMA. The Transmit Poll Demand is used to wake up the Tx DMA from suspend mode.
The Tx DMA can go into suspend mode due to an underflow error in a transmitted frame or due to the
unavailability of descriptors owned by transmit DMA. The Poll demand can be issued at any time, and
the Tx DMA will reset this command once it starts re-fetching the current descriptor from the host
memory. This register is always read 0.
Bit
Register
Reset value
Type
Description
Bit 31: 0
TPD
0x0000 0000 rrc
Transmit Poll Demand
When these bits are written with any value, the DMA reads
the current descriptor pointed to by the EMAC_DMACTD.
If the descriptor is not available (owned by host), the
transmission suspends, and the bit 2 (TU) is set in the
status register. If the descriptor is available, the
transmission resumes.
26.3.23 Ethernet DMA receive poll demand register
(EMAC_DMARPD)
The EMAC_DMARPD register enables the Rx DMA to check new descriptors. The Receive Poll
Demand is used to wake up the Rx DMA from suspend mode. The Rx DMA can enter suspend mode
due to the unavailability of descriptors owned by it.
Bit
Register
Reset value
Type
Description
Bit 31: 0
RPD
0x0000 0000 rrc
Receive Poll Demand
When these bits are written with any value, the DMA reads
the current descriptor pointed to by the EMAC_DMACRD.
If the descriptor is not available (owned by host), the
reception suspends, and the bit 7 (RU) is set in the status
register. If the descriptor is available, the reception
resumes.
26.3.24 Ethernet DMA receive descriptor list address register
(EMAC_DMARDLADDR)
The EMAC_DMARDLADDR register points to the start of the receive descriptor list. The descriptor list
is located in the host’s physical memory and must be word-aligned. The DMA enables bus-width aligned
address by making the corresponding LS bit low. Writing to the register is permitted only when the Rx
DMA stops. After the Rx DMA stops, this register must be written before the receive start command is
given.
Writing to the register is permitted only when the Rx DMA stops. In other words, the bit 1 (SR) is set 0
in the operation mode register. After the Rx DMA stops, this register can be written with a new descriptor
list address.
When the SR bit is set, the DMA uses the newly programmed descriptor base address.
If the SR is cleared and this register remains unchanged, then the DMA will use the previous descriptor
address when the Rx DMA stops.
Bit
Register
Reset value
Type
Description
Bit 31: 0
SRL
0x0000 0000 rw
Start of Receive List
These bits contain the base address of the first descriptor
in the receive descriptor list. The LSB bits (1: 0, 2: 0 or 3:
0) for 32/64/128-bit bus width are ignored and taken as
zero by the DMA. Therefore these LSB bits are read only.