DSP bus monitoring apparatus and method

A bus monitor co-located with a processor module, said module having a plurality of external contacts, said processor having a plurality of buses not all of which are accessible from said external contacts, said monitor comprising:

• an interface means for providing a trigger condition input and a bus trace output;
• a bus watching means for monitoring input connected to at least one of a plurality of buses, said bus watching means configured to generate a trigger output only when a trigger condition derived from said trigger condition input compares to a trigger event occurring on a monitor input;
• and
• a circular buffer having a means for providing a bus input connected to at least one of said buses, said circular buffer configured to continually store data from said bus data input when said trigger output is present, and to read data to said bus trace output.

A bus monitor co-located with a processor on a chip, circuit module or circuit board, said chip, module or board having a plurality of external contacts, said processor having a plurality of buses not all of which are accessible from said contacts, said monitor comprising:

• an interface connected to at least one of said plurality of external contacts and providing a trigger condition input and a bus trace output;
• a bus watching circuit having a monitor input connected to at least one of said buses, said bus watching circuit comprising a plurality of logic elements and configured to generate a trigger output when a trigger condition derived from said trigger condition input compares to a trigger event occurring on said monitor input;
• and
• a circular buffer which continuously writes data until the occurrence of said trigger output, said circular buffer having a bus data input connected to at least one of said buses and having the ability to be read from and written to via the same port, said circular buffer further being configured to store data from said bus data input in response to said trigger output and to read data to said bus trace output.

A bus monitor co-located with a processor on an integrated circuit, said integrated circuit having a plurality of external contacts, said processor having a plurality of buses not all of which are accessible from said contacts, said monitor comprising:

• an interface connected to at least one of said plurality of external contacts and providing a trigger condition input and a bus trace output;
• a bus watching circuit having a monitor input connected to at least one of said buses, said bus watching circuit configured to generate a trigger output when a trigger condition derived from said trigger condition input compares to a trigger event occurring on said monitor input, said trigger output no longer being generated when said trigger condition is no longer satisfied;
• and
• a memory having a bus data input connected to at least one of said buses, said memory having the ability to be read from and written to via the same port, and being configured to store data continually from said bus data input in response to said trigger output and to read data to said bus trace output.

A system for monitoring the internal operation of a data processing device, said processing device comprising a plurality of external contacts and one or more internal bus means, said internal bus means not accessible from said contacts, said system comprising:

• interface means connected to at least one of said plurality of external contacts for providing a trigger condition input and a bus trace output;
• bus watching means having a monitor input connected to at least one of said buses, said bus watching means generating a trigger output when a trigger condition derived from said trigger condition input compares to a trigger event occurring on said monitor input, said bus watching means further comprising a plurality of logic elements;
• a buffer means having a bus data input connected to at least one of said buses, said buffer means storing data from said bus data input in a predetermined sequential order in response to said trigger output and to read data to said bus trace output;
• means for reading data stored in said buffer means;
• and
• means for displaying said data stored in said buffer means to a user.