Standalone (SA) Mode

64-bit EDMA3 bus

32-bit configuration bus

 

 

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Figure 3. TCP2 Block Diagram

TCP2_INT TCPXEVT TCPREVT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CPU

 

 

REVT/XEVT

 

 

 

 

interrupt

 

 

 

 

 

 

 

 

generation

 

 

 

 

generation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TCP2 control

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EDMA3 I/F unit

 

Memory block

 

Processing unit

 

 

 

 

 

 

 

 

Turbo-decoder coprocessor (TCP2)

Table 1. Frame Sizes for Standalone (SA) Mode and

Shared-Processing (SP) Mode

Frame Size (F)

TCP2 Mode

40 F 20730

Standalone mode

F > 20730

Shared processing

4Standalone (SA) Mode

In standalone (SA) mode, the DSP sends the systematic and parity data, and the interleaver table. The TCP2 then works independently of the DSP (standalone), iterates a defined maximum number of times, and outputs hard decision data. In this mode, minimum DSP processing is required. A stopping criteria can be enabled to reduce the processing delay (see Section 4.3). Figure 4 shows the SA mode.

The standalone mode is used for frames in which the turbo interleaver length is less than or equal to 20730. In this mode, the systematic, parities, extrinsics, and turbo interleaver data fit within the TCP2 memory, and several iterations of decoding are run within the coprocessor without any DSP intervention.

The DSP sets up the EDMA3 to send the systematic and parity data, and the interleaver table (optional). The TCP2 then works independently of the DSP.

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TMS320C6457 Turbo-Decoder Coprocessor 2

SPRUGK1–March 2009

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Texas Instruments TMS320C6457 DSP manual Standalone SA Mode, TCP2 Mode