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AT32F435/437
Series Reference Manual
2022.11.11
Page 624
Rev 2.03
26.3.25 Ethernet DMA transmit descriptor list address register
(EMAC_DMATDLADDR)
The EMAC_DMATDLADDR register points to the start of the transmit 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 Tx DMA stops. In other words, the bit 13 (ST) is set 0
in the register 6 (operation mode register). After the Tx 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 Tx DMA stops.
Bit
Register
Reset value
Type
Description
Bit 31: 0
STL
0x0000 0000 rw
Start of Transmit List
These bits contain the base address of the first descriptor
in the transmit 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.
26.3.26 Ethernet DMA status register (EMAC_DMASTS)
The EMAC_DMASTS register contains all the status bits the DMA reports to the host. This register is
read by the software driver during an interrupt service routine or polling. Most of the bits in this register
can trigger the host to be interrupted. The bits in this register cannot be cleared when read. Writing 1’b1
to the bit [16: 0] (unreserved) in this register clears them. Writing 1’b0 has no effect. Each bit (bit [16:
0] ) can be masked through the corresponding bit in the interrupt enable mask register.
Bit
Register
Reset value
Type
Description
Bit 31: 30 Reserved
0x0
resd
Kept at its default value.
Bit 29
TTI
0x0
ro
Timestamp Trigger Interrupt
This bit indicates an interrupt event in the time stamp
generator block. The software must read the
corresponding register to get interrupt sources.
This bit is applicable only when the IEEE1588 time stamp
feature is enabled. Otherwise, this bit is reserved.
Bit 28
MPI
0x0
ro
MAC PMT Interrupt
This bit indicates an interrupt even in the PMT. The
software must read the Ethernet PMT control and status
register (EMAC_MACPMTCTRLSTS) to get the interrupt
sources and clear them in order to reset this bit to 1'b0.
This bit is applicable only when the PMT function is
enabled. Otherwise, this bit is reserved.
Bit 27
MMI
0x0
ro
MAC MMC Interrupt
This bit indicates an interrupt event in the MMC. The
software must read the corresponding register to get
interrupt sources and clear them in order to reset this bit
to 1'b0.
This bit is applicable only when the MAC MMC is enabled.
Otherwise, this bit is reserved.
Bit 26
Reserved
0x0
resd
Kept at its default value.
Bit 25: 23 EB
0x0
ro
Error Bits
These bits indicate the type of error that caused a bus
error. They are applicable only when the bit 13 (FBI) is set.
This filed does not generate an interrupt.
000: Error during data transfer by Rx DMA
011: Error during read transfer by Tx DMA
100: Error during Rx DMA descriptor write access
101: Error during Tx DMA descriptor write access
110: Error during Rx DMA descriptor read access
111: Error during Tx DMA descriptor read access
Note: 001 and 010 are reserved.
Bit 22: 20 TS
0x0
ro
Transmit Process State