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Josť A. Ruiz
06/14/13 02:49
Read: 1133 times
United Kingdom

#189935 - FPGA on-chip debugging redundant?
Responding to: Richard Erlacher's previous message
That's a very strong objection. A debugger won't be much help unless it somehow encompasses at least some of the actual logic of the FPGA that the MCU is controlling... a project like this may easily spiral out of control by attempting to make it flexible enough to debug off-CPU logic, or if it doesn't it may just be nearly useless as you say.

Besides, if your FPGA is going to include some kind of 'ChipScope' core (a sort of on-FPGA logic analyzer), in principle you could use it to monitor the state of the MCU to a limited extent (e.g. by tracing the PC register) which would make a debugger much less necessary. I wonder what do people do in cases like this...

I think I will just modify the core to add some ISP capability; that alone will make working with it much easier. I will leave debugging alone until I find out how other FPGA CPU cores do it :)

Anyway, I think on-chip debugging is of limited value in a real time embedded project of any complexity; often it's just easier to use a bunch of GPIO pins and a 'scope, or a serial port.

List of 23 messages in thread
OCD for FPGA core      Josť A. Ruiz      06/01/13 03:48      
   Serial-to-EC2 reverse engineering      Josť A. Ruiz      06/01/13 06:12      
   C2spec.pdf      Jim Granville      06/01/13 06:36      
   Reality Check......        Michael Karas      06/01/13 08:24      
      Agreed      Josť A. Ruiz      06/01/13 12:53      
         multi-threaded      Jim Granville      06/01/13 16:54      
      FPGA and soft cores      Oliver Sedlacek      06/03/13 02:20      
         Yes ... but which debugger?       Richard Erlacher      06/03/13 10:48      
            Actually no      Oliver Sedlacek      06/04/13 01:55      
               Who's "they"      Richard Erlacher      06/04/13 12:48      
               I wouldn't use FPGA unless I need more than just the core      Richard Erlacher      06/07/13 14:50      
                  FPGA on-chip debugging redundant?      Josť A. Ruiz      06/14/13 02:49      
                  debugging embedded processors        Andy Peters      06/25/13 18:56      
                     That's good to know.      Richard Erlacher      06/26/13 11:13      
   nice idea      Maarten Brock      06/02/13 07:03      
      Von Neumann first      Josť A. Ruiz      06/02/13 10:23      
   if that were the case ...      Erik Malund      06/03/13 15:19      
      Poorly chosen acronym...      Josť A. Ruiz      06/14/13 02:59      
         On Chip Debug is common        Jim Granville      06/14/13 03:44      
            On Chip Debug *is* a very good idea indeed!      Andy Neil      06/15/13 13:44      
               PC        Maarten Brock      06/15/13 14:09      
                  PC        Michael Karas      06/17/13 06:55      
                     PC        Oliver Sedlacek      06/18/13 02:19      

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