TI C54 EVM Quick Introduction

1
TI C54 EVM Quick Introduction

• Prepared by
• Ryanth Atmadja
• August 1999
• http//www.ti.com/sc/docs/products/dsp/overview.ht
  m
• http//www.ti.com/sc/docs/products/dsp/tms320c541.
  html
• http//www.ti.com/sc/docs/dsps/hotline/wizsup5xx.h
  tm

2
Where C54 should be used?

• The C54 is specifically designed for low-powered
  real-time embedded applications, such as
  telecommunications and voice IP
• cellular phones, PCS terminals, pagers, IP
  phones, portable information systems, digital
  hearing aids, etc. taken from C54 web site.
• Two CMU undergrads had used the C54 EVM to
  control acoustical noise, and to process data
  from a surveillance camera.

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TI C54 EVM Specs

• Processor
• Parameter name TMS320C541-40
• Word size 16 bits (designed for fixed-point)
• Clock speed 40 MHz
• Peak MIPS 40
• Non-superscalar
• Memory
• Internal RAM (words) 5 K (shared data/program)
• External RAM (words) 64K/64K (data/program)
• Misc.
• 2 serial ports (one is free as an external serial
  port)
• Analog interface circuit (D/A and A/D converters)
  where a microphone and a speaker may be attached.
  Additional audio I/O must use the PCs sound
  card.
• EVM is a PC/AT plug-in card
• DMA not available (i.e., the host PC and EVM
  communication is interrupt based only.)

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Experience to be shared

• Correct initialization (C54, serial port, analog
  interface circuit AIC, host PC - EVM
  communication, interrupt table) is a very
  critical component for proper program execution.
  I happened to forget setting the correct value
  for the CPL bit (part of ST1 register), which
  caused a whole code unable to run (loops did not
  work, functions could not be called, etc.)
• Watch for the status registers (ST0, ST1, PMST,
  and SPC) to get clues while debugging.
• Avoid the data and program spaces from
  overlapping in the internal RAM. Memory
  allocation is done in the .cmd or linker file. I
  once used a ready-made .cmd file from TI (I
  guess) and it allocated memory such that the data
  and program overlapped, this caused a problem
  since as a data stack grew up, it could corrupt
  the program somewhere. This particular mistake
  has been known to make C54 codes unstable when
  run in the EVM -- sometimes the codes worked,
  other times did not.

5
Experience to be shared (cont.)

• Since the EVMs internal memory is very limited
  (5 K words), a special care should be taken when
  allocating local variables. Or, global variables
  can be used to exploit the slower but much larger
  external memory (64 K for each data and program).
• The C-compiler does not take advantage of the
  specialized DSP features, such as the MAC
  (multiply-accumulate) instruction, and
  circular-buffering. In general, I estimate that
  hand-assembled programs can be faster by at least
  a factor of two.
• We may also speed up the code by manually
  optimizing the assembly code created by the
  C-compiler.
• But, I believe that manual conversion to assembly
  should be done after we have a final version of
  the C-code, since assembly programming is
  inflexible.
• Use the debugger often. This will save time
  compared to blindly debugging a C54 code by
  trial-and-error.

6
Experience to be shared (cont.)

• Audio I/O interrupt handling can be done only
  with assembly programming.
• The C54 is a fixed-point processor. Therefore,
  if fractional or non-integer arithmetics is
  necessary in the DSP algorithm, it requires extra
  programming than with floating-point processors
  such as the C30.
• A possible DSP development methodology with the
  C54 EVM is as follows
• Simulations (e.g., on MATLAB)
• Implement the DSP algorithm only with PC in C.
• Develop a programming framework for the EVM, if
  necessary.
• Modify C-code for use with the C54 EVM.
• Hand-optimize the assembly code (optional).