SPRUI33H November 2015 – June 2024 TMS320F280040-Q1 , TMS320F280040C-Q1 , TMS320F280041 , TMS320F280041-Q1 , TMS320F280041C , TMS320F280041C-Q1 , TMS320F280045 , TMS320F280048-Q1 , TMS320F280048C-Q1 , TMS320F280049 , TMS320F280049-Q1 , TMS320F280049C , TMS320F280049C-Q1
The C28x device with VCU (C28x+VCU) processor extends the capabilities of the C28x fixed-point or floating-point CPU by adding registers and instructions to support the following algorithm types:
Viterbi decoding is commonly used in baseband communications applications. The viterbi decode algorithm consists of three main parts: branch metric calculations, compare-select (viterbi butterfly), and a traceback operation. Table 2-2 shows a summary of the VCU performance for each of these operations.
Viterbi Operation | VCU Cycles |
---|---|
Branch Metric Calculation (code rate = 1/2) | 1 |
Branch Metric Calculation (code rate = 1/3) | 2p |
Viterbi Butterfly (add-compare-select) | 2(1) |
Traceback per Stage | 3(2) |
CRC algorithms provide a straightforward method for verifying data integrity over large data blocks, communication packets, or code sections. The C28x+VCU can perform 8-, 16-, and 32-bit CRCs. For example, the VCU can compute the CRC for a block length of 10 bytes in 10 cycles. A CRC result register contains the current CRC which is updated whenever a CRC instruction is executed.
Complex math is used in many applications; a few are:
The complex FFT is used in spread spectrum communications, as well as many signal processing algorithms.
Complex filters improve data reliability, transmission distance, and power efficiency. The C28x+VCU can perform a complex I and Q multiply with coefficients (four multiplies) in a single cycle. In addition, the C28x+VCU can read/write the real and imaginary parts of 16-bit complex data to memory in a single cycle.
Table 2-3 shows a summary of a few complex math operations enabled by the VCU.
Complex Math Operation | VCU Cycles | Notes |
---|---|---|
Add or Subtract | 1 | 32 +/- 32 = 32-bit (Useful for filters) |
Add or Subtract | 1 | 16 +/- 32 = 15-bit (Useful for FFT) |
Multiply | 2p | 16 x 16 = 32-bit |
Multiply and Accumulate (MAC) | 2p | 32 + 32 = 32-bit, 16 x 16 = 32-bit |
Repeat Multiply and Accumulate (MAC) | 2p+N | Repeat MAC. Single cycle after the first operation. |
Throughout this chapter the following notations are used:
For more information, see the TMS320C28x Extended Instruction Sets Technical Reference Manual.