How to create a look up table for a RAM application

You can use a one way hash function to do the reduction. A CRC is a good example, one can think of others. It will probably not solve your space problem though.

Erez.

Assuming the max number of endpoints is known, make another RAM

For example, if only 4 endpoints, then change the 7 bit field to a 2 bit field and, at enumeration, store the numbers in the smaller ram.

Hul

Vazquez wrote: : Dear Sir or Madame, : : I have a data packet which has a 13 bit field for an USB : application(7bit + 4bit + 1bit + 1bit). : : : Because of lack of memory I do create a RAM which : has a data input width of only 10 bit. The write address of : the RAM is [4..0], i.e. 32 words ? 10 bit. : The words which are written into the RAM : are searched for later (CAM-like function). : : The problem: I have to reduce 13 bit to 10 bit without losing the : significance of the 13 bit. But it is not possible to leave out for : example : two bits of the 7bit (usb address) because the enumeration by the host : is not : predictable. : : How could I solve this problem? : : Thank you very much. : : Best regards : : Andres Vazquez : G&D System Development