GD32F10x User Manual
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22.3.2.
MAC function overview
MAC module can achieve the following functions:
Data package (transmission and reception)
Frame detecting/decoding and frame boundary delimitation.
Addressing (handling source address and destination address).
Error conditions detect.
Medium access management in Half-duplex mode
Medium allocation (prevent conflicts).
Conflict resolution (dealing with conflicts).
The MAC module can work in two modes
Half-duplex mode: with the CSMA/CD algorithm to contend for using of the physical
medium, at the same time only one transmission direction is active between two
stations is active.
Full-duplex mode: simultaneous transmission and reception without any conflict mode,
if all of the following conditions are satisfied: 1) PHY supports the feature of
transmission and reception operations at the same time. 2) Only two devices connect
to the LAN and the two devices are both configured for Full-duplex mode.
Transmission process of MAC
All transactions are controlled by the dedicated DMA controller and MAC in Ethernet. After
received the sending instruction, the TxDMA fetches the transmit frames from system memory
and pushes them into the TxFIFO, then the data in TxFIFO are poped to MAC for sending on
MII/RMII interface. The method of popping is according to the selected TxFIFO mode (Cut-
Through mode or Store-and-Forward mode, the specific definition see the next
paragraph).For convenient, application can configure automatically hardware calculated CRC
and insert it to the FCS domain of Ethernet frame function. The entire transmission process
complete when the MAC received the frame termination signal from transmit FIFO. When
transmission completed, the transmission status information will be composed of MAC and
write return to the DMA controller, the application can query through the DMA current transmit
descriptor.
Operation for popping data from FIFO to the MAC has two modes:
In Cut-Through mode, as soon as the number of bytes in the FIFO crosses or equals
the configured threshold level or when the end-of-frame flag in descriptor is written, the
data is ready to be popped out and forwarded to the MAC. The threshold level is
configured using the TTHC bits of ENET_DMA_CTL.
In Store-and-Forward mode, only after an integrated frame is stored in the FIFO, the
frame is popped towards the MAC. But there is another condition for FIFO popping out
Summary of Contents for GD32F10 Series
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Page 416: ...GD32F10x User Manual 416 shadow register updates every update event ...
Page 427: ...GD32F10x User Manual 427 value ...
Page 518: ...GD32F10x User Manual 518 These bits are not used in SPI mode ...