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2.5.4.7End of Packet (EOP) Flag

When set, this flag indicates that the descriptor points to a packet buffer that is last for a given packet. In the case of a single fragment packet, both the start of packet (SOP) and EOP flags are set. Otherwise, the descriptor pointing to the last packet buffer for the packet sets the EOP flag. This bit is set by the software application and is not altered by the EMAC.

2.5.4.8Ownership (OWNER) Flag

When set, this flag indicates that all the descriptors for the given packet (from SOP to EOP) are currently owned by the EMAC. This flag is set by the software application on the SOP packet descriptor before adding the descriptor to the transmit descriptor queue. For a single fragment packet, the SOP, EOP, and OWNER flags are all set. The OWNER flag is cleared by the EMAC once it is finished with all the descriptors for the given packet. Note that this flag is valid on SOP descriptors only.

2.5.4.9End of Queue (EOQ) Flag

When set, this flag indicates that the descriptor in question was the last descriptor in the transmit queue for a given transmit channel, and that the transmitter has halted. This flag is initially cleared by the software application prior to adding the descriptor to the transmit queue. This bit is set by the EMAC when the EMAC identifies that a descriptor is the last for a given packet (the EOP flag is set), and there are no more descriptors in the transmit list (next descriptor pointer is NULL).

The software application can use this bit to detect when the EMAC transmitter for the corresponding channel has halted. This is useful when the application appends additional packet descriptors to a transmit queue list that is already owned by the EMAC. Note that this flag is valid on EOP descriptors only.

2.5.4.10Teardown Complete (TDOWNCMPLT) Flag

This flag is used when a transmit queue is being torn down, or aborted, instead of allowing it to be transmitted. This would happen under device driver reset or shutdown conditions. The EMAC sets this bit in the SOP descriptor of each packet as it is aborted from transmission.

Note that this flag is valid on SOP descriptors only. Also note that only the first packet in an unsent list has the TDOWNCMPLT flag set. Subsequent descriptors are not even processed by the EMAC.

2.5.4.11Pass CRC (PASSCRC) Flag

This flag is set by the software application in the SOP packet descriptor before it adds the descriptor to the transmit queue. Setting this bit indicates to the EMAC that the 4 byte Ethernet CRC is already present in the packet data, and that the EMAC should not generate its own version of the CRC.

When the CRC flag is cleared, the EMAC generates and appends the 4-byte CRC. The buffer length and packet length fields do not include the CRC bytes. When the CRC flag is set, the 4-byte CRC is supplied by the software application and is already appended to the end of the packet data. The buffer length and packet length fields include the CRC bytes, as they are part of the valid packet data. Note that this flag is valid on SOP descriptors only.

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Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO)

SPRUEQ6–December 2007

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Texas Instruments TMS320DM646x End of Packet EOP Flag, Ownership Owner Flag, End of Queue EOQ Flag, Pass CRC Passcrc Flag
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TMS320DM646x specifications

The Texas Instruments TMS320DM646x series is a powerful family of digital media processors designed to handle high-performance applications in video, imaging, and audio processing. These devices leverage advanced technologies to deliver efficient processing capabilities for a variety of embedded systems, making them ideal for multimedia solutions.

At the core of the TMS320DM646x is the versatile DSP architecture, which optimizes performance for digital signal processing tasks. This architecture allows for real-time processing, enabling the devices to handle complex algorithms necessary for image and video compression, thereby meeting the rigorous demands of modern multimedia applications.

One of the standout features of the TMS320DM646x series is its dual-core architecture. This consists of a Digital Signal Processor (DSP) alongside an ARM-based application processor. The DSP is predominantly employed for critical processing tasks, allowing it to execute high-throughput data streams efficiently, while the ARM processor manages control tasks and user interfaces. This division of labor enhances overall system performance and responsiveness.

The series supports a wide range of video formats and technologies, including HD video encoding and decoding, which accommodates HD resolution content essential for today’s multimedia applications. Furthermore, the TMS320DM646x integrates hardware accelerators for video compression standards such as H.264 and MPEG-4, which significantly reduce the processing burden on the CPU, resulting in lower power consumption and higher efficiency.

Networking capabilities are another significant feature of the TMS320DM646x. With support for Ethernet, the device can handle streaming media applications and connectivity, facilitating the transmission of high-quality audio and video over the internet. This connectivity is crucial for developing robust IPTV and streaming solutions.

Power management is a primary focus in the design of the TMS320DM646x series. The processors are built to operate efficiently with minimal power consumption, making them suitable for portable and battery-operated devices. The low power characteristics do not compromise performance, enabling high computational capabilities while maintaining energy efficiency.

Overall, the Texas Instruments TMS320DM646x series offers an exceptional combination of processing power, advanced multimedia capabilities, and energy efficiency. It optimally supports a wide array of applications, from video processing and image analysis to audio encoding. This comprehensive feature set, along with its robust architecture, positions the TMS320DM646x as a leading choice for developers in the digital media space.
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