Start Development

Sorry, not complete yet, you will find some starting point in the examples delivered with the toolchain...

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Todo

howto compile examples

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Blackfin programming reference

If you are new to blackfin development it may be a good idea to read this document.

Blackfin Processor Hardware Reference

Pitfalls

Alignment

Every command must be word aligned. When you access the memory, word accesses must be word aligned, long word accesses must be long word aligned.

Don't use the .align directive . It doesn't works with the toolchain. Use .byte directives to do that.

Subroutines / Calls

Every subroutine that calls subroutines must start with LINK and end with UNLINK to save the return address to the stack. The blackfin CPU doesn't do that automaticly.

Example:

sub:
  LINK 0x0

  ...
  CALL sub2
  ...

  UNLINK
  RTS

STOP-Mode

Switch your scope to the STOP-Mode if you don't need capturing during your software is working. Sometimes i got unpredictable crashs when the device was in AUTO-Mode. Hope to find a reason for this thing soon.

Unlock the Keyboard

If you need keyboard interaction, first you should unlock the keyboard for user inputs.

This lines will do the job:

  R0=0
  CALL Set_KeyLock

The keyboard is locked, because the serial interface is used to upload and start your software.

You can see that its locked if the only keycode you get is KC_KEYLOCK (0xc9).