AnsweredAssumed Answered

Sharc memory address decoding

Question asked by msonet on Mar 6, 2013
Latest reply on Mar 7, 2013 by MaheshN

Hi,

 

I have a question regarding the address decoding on a Sharc Dsp (21469 in my case).

 

How can the dsp distinguish between a NW 32-bit address and a NW 48-bit address ?

The address bits 18 to 20 are used to separate the LW, NW and SW cases, but both 32-bit and 48-bit accesses are identified as Normal Word.

 

I looked at the 21469 datasheet to check the address range for each space in block 0 (Table 3):

 

Extended Precision Normal or Instruction Word (48 bits)

Block 0 SRAM

0x0008 C000–0x0009 3FFF

 

Normal Word (32 bits)

Block 0 SRAM

0x0009 2000–0x0009 DFFF

 

So the address spaces start at a different addresses, but there is also an overlap, for example @ 0x92000.

How can I determine which space is used by doing a pm(0x92000) ?

 

Best regards,

Mathieu

Outcomes