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MJoergen / HyperRAM

Portable HyperRAM controller

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Memory corruption during burst write

MJoergen opened this issue · comments

commented

Short description

This bug only happens when writing with burstcount > 1, i.e. when issuing writes of more than 2 bytes. Basically, the controller ignores the byteenable input on all but the first clock cycle. This bug was observed in the ILA while investigating issue #2.

To reproduce

Start a write with burstcount = 2 and write the following:

  1. cycle: data = X"BBAA" with byteenable = "11"
  2. cycle: data = X"DDCC" with byteenable = "01"

Expected behavior

The memory is updated with the three bytes X"AA", X"BB", and X"CC".

Observed behavior

Four bytes are written to memory, i.e. the fourth byte X"DD" gets written as well, thus corrupting one byte of memory.

commented

Fixed in commit 11fb085