GD32F20x User Manual
820
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TB2AP/TTSH[15:0]
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Bits
Fields
Descriptions
31:0
TB2AP/TTSH[31:0]
Transmit buffer 2 address pointer (or next descriptor address) / Transmit frame
timestamp high 32-bit value bits
Before transmitting frame, application must configure these bits for transmit buffer 2
address (TB2AP) or the next descriptor address which is decided by descriptor type
is ring or chain. When the transmitting frame is complete, these bits can be changed
to the timestamp high 32-bit value (TTSH) for transmitting frame TTSEN =1. When
these bits stand for buffer 2 address (TCHM=0), the alignment is no limitation. When
these bits stand for the next descriptor address (TCHM=1), these bits must be word-
alignment. When these bits stand for timestamp high 32-bit value, the TTSEN and
LSG bit of current descriptor must be set.
RxDMA configuration
The receiving process of the RxDMA controller is described detailed as below:
1.
Applications initialize the receive descriptors with the DAV bit (RXDES0[31]) is set
2.
Setting the SRE bit in ENET_DMA_CTL register to make RxDMA controller entering
running state. In running state, the RxDMA controller continually fetching the receive
descriptors from descriptor table whose starting address is configured in
ENET_DMA_RDTADDR register by application. If the DAV bit of the fetched receive
descriptor is set, then this descriptor is used for receiving frame. But if the DAV bit is
reset which means this receive descriptor cannot be used by RxDMA, the RxDMA
controller will enter suspend state and operation goes to Step 9
3.
From the valid receive descriptor (DAV=1), the RxDMA controller marks the receiving
control bit and data buffer address
4.
Processing the received frames and transfer data to the receive buffer from the
RxFIFO.
5.
If all frame data has completely transferred or the buffer is full, the RxDMA controller
fetches the next descriptor from receive descriptor table.
6.
If the current receiving frame transfer is complete, the operation of RxDMA goes to
Step7. But if not complete, two conditions may occur:
1) The next descriptor’s DAV bit is reset. The RxDMA controller sets descriptor error bit
DERR in RDES0 if flushing function is enabled. The RxDMA controller closes current
descriptor by resetting DAV bit and sets the LSG bit (if flushing is enabled) or resets the
LSG bit (if flushing is disabled). Then the operation goes to Step 8.
Содержание GD32F20 Series
Страница 1: ...GigaDevice Semiconductor Inc GD32F20x ARM Cortex M3 32 bit MCU User Manual Revision 2 2 Oct 2019 ...
Страница 191: ...GD32F20x User Manual 191 Bits Fields Descriptions 31 0 TRNDATA 31 0 32 Bit Random data ...
Страница 290: ...GD32F20x User Manual 290 conversion is ongoing ...
Страница 325: ...GD32F20x User Manual 325 15 0 ALRM 15 0 RTC alarm value low ...
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Страница 523: ...GD32F20x User Manual 523 clears AERR bit by writing 0 to it ...