Video Capture Registers

3.13.8 Video Capture Channel x Threshold Register (VCATHRLD, VCBTHRLD)

The video capture channel x threshold register (VCATHRLD, VCBTHRLD) determines when DMA requests are sent. VCxTHRLD is shown in Figure 3–36 and described in Table 3–21.

The VCTHRLD1 bits determine when capture DMA events are generated. Once the threshold is reached, generation of further DMA events is disabled until service of the previous event(s) begins (the first FIFO read by the DMA occurs).

In BT.656 and Y/C modes, every two captured pixels represent 2 luma values in the Y FIFO and 2 chroma values (1 each in the Cb and Cr FIFOs). Depend- ing on the data size and packing mode, each value may be a byte (8-bit BT.656 or Y/C), half-word (10-bit BT.656 or Y/C), or subword (dense pack 10-bit BT.656 or Y/C) within the FIFOs. Therefore, the VCTHRLD1 doubleword number represents 8 pixels in 8-bit modes, 4 pixels in 10-bit modes, or 6 pixels in dense pack 10-bit modes. Since the Cb and Cr FIFO thresholds are repre- sented by ½ VCTHRLD1, certain restrictions are placed on what VCTHRLD1 values are valid (see section 2.3.3).

In raw data mode, each data sample may occupy a byte (8-bit raw mode), half- word (10-bit or 16-bit raw mode), subword (dense pack 10-bit raw mode), or word (20-bit raw mode) within the FIFO, depending on the data size and pack- ing mode. Therefore, the VCTHRLD1 doubleword number represents 8 sam- ples, 4, samples, 6 samples, or 2 samples, respectively.

In TSI mode, VCTHRLD1 represents groups of 8 samples with each sample occupying a byte in the FIFO.

The VCTHRLD2 bits behave identically to VCTHRLD1, but are used during field 2 capture. It is only used if the field 2 DMA size needs to be different from the field 1 DMA size for some reason (for example, different captured line lengths in field 1 and field 2). If VT2EN is not set, then the VCTHRLD1 value is used for both fields.

Note that the VCTHRLDn applies to data being written into the FIFO. In the case of 8-bit BT.656 or Y/C modes, this means the output of any selected filter.

SPRU629

Video Capture Port

3-65

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Texas Instruments TMS320C64x DSP manual SPRU629
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TMS320C64x DSP specifications

The TMS320C64x DSP family from Texas Instruments represents a significant milestone in the realm of digital signal processing. Launched as part of the C6000 series, the C64x DSPs are designed for high-performance applications requiring intensive computational capabilities, such as telecommunications, audio processing, video processing, and industrial control systems.

One of the standout features of the TMS320C64x DSP is its VLIW (Very Long Instruction Word) architecture, which allows for an exceptionally high level of parallelism. This architecture enables multiple instructions to be executed simultaneously, boosting the overall throughput and allowing for complex data processing tasks to be completed more quickly than with conventional DSPs.

The C64x DSPs also boast an impressive clock frequency range, typically up to 1 GHz, delivering substantial computational power for real-time processing goals. Additionally, these processors feature extensive on-chip memory, including L1 and L2 cache, which significantly enhances data access speeds and helps reduce bottlenecks during high-demand processing tasks.

Another key characteristic of the TMS320C64x family is its support for advanced instruction sets optimized for specific applications. These include SIMD (Single Instruction, Multiple Data) capabilities, allowing for efficient handling of large datasets often involved in multimedia processing or complex signal manipulation.

For connectivity, these DSPs often integrate advanced interfaces such as EMIF (External Memory Interface) and McBSP (Multichannel Buffered Serial Port), facilitating seamless interaction with a variety of peripheral devices. This ensures that the DSP can suit different application needs and integrate well into various system architectures.

Texas Instruments emphasizes low power consumption with the C64x DSPs, making them ideal for portable or energy-sensitive applications. Advanced power management techniques and technologies, such as dynamic voltage and frequency scaling, are incorporated to further enhance energy efficiency without compromising performance.

In summary, the Texas Instruments TMS320C64x DSP family stands out due to its high-performance capabilities driven by a VLIW architecture, high clock speeds, extensive memory options, a rich instruction set, and advanced connectivity features, all while maintaining power efficiency. These characteristics make it an exceptional choice for developers looking to integrate robust digital signal processing into their applications, whether in telecommunications, audio and video processing, or embedded control systems.
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