Subversion Repositories open8_urisc

Last modification

• Rev 251, 2020-06-09 23:37:42 GMT
• Author: jshamlet

• Log message:

  Added RAM write fault detection, which can be used to indicate a memory write violation by the CPU. This allows a clean shutdown in the event of a memory problem/program crash.
  
  Fixed a bug in the status_led.vhd entity that kept the flashing light function from working. The new code uses a maximal length 24-bit LFSR to create long delays. This is more efficient than a binary counter, but results in non-exact frequencies as a function of SYSTEM_FREQUENCY / (2^24-1).
  
  Added the ability to use unsigned offsets to the LDO/STO instructions. The original behavior of signed offsets is preserved if the Unsigned_Index_Offsets is left unset or set to FALSE. While inserting this code, pipeline registers were also inserted into the address generation logic for indexed instructions. This simplifies the final multiplexor and improves FMax at the slight expense of LDO/SDO now taking one additional clock cycle to execute.