Transmit buffers serial#
Transmit buffers software#
Transmit buffers professional#
Transmit buffers mac#

The Transmit Buffer is empty (the output address in the TX_OUTPUT register equals the input address in the TX_INPUT register) вЂ“ all packets have been transmitted.ДЇigure 3b shows the situation when the next packet is written to the buffer and not yet transmitted. Writing data to the Transmit Buffer.ДЇigure 3a shows the situation before the next packet is written to the buffer. Figure 3 illustrates these processes.ДЇigure 3.

Transmit buffers software#

When the software decides to start over at the beginning of the buffer, 00000000h must first be written at the end of the last packet in the buffer before writing the next packet at the beginning of the buffer. Whereas the Receive Buffer is written by the EMAC32 and read by software, the Transmit Buffer is written by software and read by the EMAC32. The Transmit Buffer layout is similar to the Receive Buffer layout. At this stage the Receive Buffer still contains only one packet of data. A 32-bit word with value 00000000h is written to address RX_INPUT and then RX_INPUT is set to point to the beginning of the buffer. At this stage, the Receive Buffer contains one packet of data.ДЇigure 2c shows the situation when the next packet is received and there is not enough space behind the previously received packet. The RX_INPUT register is then updated to point to the first 4-byte boundary behind the received packet of data. The packet of data is written from address RX_INPUT + 4 and then the size of the packet written to address RX_INPUT. The Receive Buffer is empty (the output address in the RX_OUTPUT register equals the input address in the RX_INPUT register).ДЇigure 2b shows the situation when the next packet is received and there is enough space behind the written packet. Receiving data into the Receive Buffer.ДЇigure 2a shows the situation before the next packet is received. Figure 2 illustrates these processes.ДЇigure 2. If the available space behind the address pointed to by the RX_INPUT register is less than the maximum space needed for a packet, 00000000h is written to address RX_INPUT and the RX_INPUT register is set to the beginning of the buffer (as defined by the value contained in the RX_START register). After that it writes the length of the packet to address RX_INPUT and sets RX_INPUT to the first 4-byte boundary behind the PACKET_DATA field. When receiving a packet, the EMAC32 starts writing at address RX_INPUT + 4 with the received PACKET_DATA until the whole packet is received and written to memory.

The value in the RX_INPUT register points to the location where the next packet structure will be placed in the Receive Buffer. Unused data bytes between the previous PACKET_DATA and the next PACKET_SIZE are undefined.

Transmit buffers mac#

The PACKET_DATA contains the destination MAC address, the source MAC address, the type/length field and the data. The PACKET_SIZE is located at a 4-byte boundary. The PACKET_SIZE is a 32-bit word which indicates the length of the next PACKET_DATA in bytes. Generic layout for Receive and Transmit Buffers.

Transmit buffers serial#

Even something as 'simple' as the console's serial port generally has special receive/transmit buffers, although for single characters.The EMAC32 uses the following generic layout for the Receive and Transmit buffers:ДЇigure 1. What's 'special' about them is they often have special hardware support to insure a packet/frame is processed within the real-time requirements of the interface. Generally they are 'special' queues to deal with packets/frames arriving on an interface or waiting to be transmitted on an interface. In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage. Usage of this posting's information is solely at reader's own risk.

Transmit buffers professional#

Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose.