![NXP Semiconductors LPC43Sxx Скачать руководство пользователя страница 852](http://html1.mh-extra.com/html/nxp-semiconductors/lpc43sxx/lpc43sxx_user-manual_1721827852.webp)
UM10503
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
852 of 1441
NXP Semiconductors
UM10503
Chapter 28: LPC43xx/LPC43Sxx Ethernet
6
FUF
Forward undersized good frames
When set, the Rx FIFO will forward Undersized frames (frames with no Error and
length less than 64 bytes) including pad-bytes and CRC).
When reset, the Rx FIFO will drop all frames of less than 64 bytes, unless it is already
transferred due to lower value of Receive Threshold (e.g., RTC = 01).
0
R/W
7
FEF
Forward error frames
When this bit is reset, the Rx FIFO drops frames with error status (CRC error, collision
error, , watchdog timeout, overflow). However, if the frame’s start byte (write) pointer
is already transferred to the read controller side (in Threshold mode), then the frames
are not dropped. When FEF is set, all frames except runt error frames are forwarded
to the DMA. But when RxFIFO overflows when a partial frame is written, then such
frames are dropped even when FEF is set.
0
R/W
12:8
-
Reserved
0
RO
13
ST
Start/Stop Transmission Command
When this bit is set, transmission is placed in the Running state, and the DMA checks
the Transmit List at the current position for a frame to be transmitted. Descriptor
acquisition is attempted either from the current position in the list, which is the
Transmit List Base Address set by the DMA_TRANS_DES_ADDR register or from
the position retained when transmission was stopped previously. If the current
descriptor is not owned by the DMA, transmission enters the Suspended state and
Transmit Buffer Unavailable (DMA_STAT register, bit 2) is set. The Start Transmission
command is effective only when transmission is stopped. If the command is issued
before setting the DMA_TRANS_DES_ADDR register, then the DMA behavior is
unpredictable.
When this bit is reset, the transmission process is placed in the Stopped state after
completing the transmission of the current frame. The Next Descriptor position in the
Transmit List is saved, and becomes the current position when transmission is
restarted. The stop transmission command is effective only the transmission of the
current frame is complete or when the transmission is in the Suspended state.
0
R/W
16:14
TTC
Transmit threshold control
These three bits control the threshold level of the MTL Transmit FIFO. Transmission
starts when the frame size within the MTL Transmit FIFO is larger than the threshold.
In addition, full frames with a length less than the threshold are also transmitted.
These bits are used only when the TSF bit (Bit 21) is reset.
000 = 64
001 = 128
010 = 192
011 = 256
100 = 40
101 = 32
110 = 24
111 = 16
0
R/W
19:17
-
Reserved
0
RO
Table 637. DMA operation mode register (DMA_OP_MODE, address 0x4001 1018) bit description
…continued
Bit
Symbol
Description
Reset
value
Access