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Jim Granville
01/15/13 18:28
Read: 797 times


 
#189180 - If you really want to use ds80c320
Responding to: James Brzycki's previous message
James Brzycki said:
Just to add in that I do have a programmer for prom's, I work in pcb assembly and test and I knew that for those you need a special programmer.


If you really want to use ds80c320, and EEPROM, even after being told there are devices with inbuilt flash and Boot loaders for a couple of dollars, then these are the issues you will face.

What you ask can be done
a) ds80c320 has no ROM, so it always needs to be fed code externally.
b) EEPROM cannot supply opcodes whilst it is programming

Thus the solution is to use TWO EEPROMS, (these can be stacked, with a couple of pins separated) and use some means to select.
One chip (use read only or ROM) holds the Boot loader code, you first load this using your parallel programmer, with Boot code you find/modify.

The other chip is for your changing code.

You add a simple Mux (eg google 4 x 2:1 Multiplexer) to flip between Boot and run, via a switch, or using PC-uart handshake lines.

During PGM phase, DS80C320 fetches opcodes from your ROM EEPROM, and uses /RN and /WR to access the Other EEPROM (RUN).

Then for run, your MUX swaps RUN.OEN from /RD to PSEN, and the other ROM.OEN can disable, or swap conversely from PSEN to RD if you want to include tables, or fonts, or similar in the ROM chip.
A reset now starts from RUN.

ROM.WR is disabled, (pgm that in your programmer) and RUN.WR is either always connected (dangerous), or connected to uC.WRN only in Boor, and disabled in Run.






List of 40 messages in thread
TopicAuthorDate
Regarding Typical memory connection for a ds80c320      James Brzycki      01/13/13 19:39      
   drop it!      Erik Malund      01/13/13 20:10      
   same question - same answers      Andy Neil      01/13/13 23:32      
   It won't work      Andy Neil      01/13/13 23:41      
      Andy Neil's previous message      James Brzycki      01/14/13 06:41      
         little feet stamping the floor      Erik Malund      01/14/13 07:33      
            little feet stamping the floor      James Brzycki      01/14/13 07:45      
               Erik doesn't like it when you don't do what he wants      Richard Erlacher      01/14/13 11:11      
                  KISS      Erik Malund      01/14/13 11:39      
                     Not exactly ...      Richard Erlacher      01/14/13 23:35      
                        I find it odd that you      Erik Malund      01/15/13 09:29      
                           just to add      James Brzycki      01/15/13 11:24      
                              If you really want to use ds80c320      Jim Granville      01/15/13 18:28      
                                 Not necessary ...      Andy Neil      01/15/13 23:31      
                                    What about the other option?      Richard Erlacher      01/16/13 02:00      
                                    Yes, but ..      Jim Granville      01/16/13 12:56      
                              So your development cycle will be...      Andy Neil      01/16/13 01:01      
                           What about that other post?      Richard Erlacher      01/16/13 01:50      
                              reply to all      James Brzycki      01/16/13 14:12      
                                 'something'      Erik Malund      01/16/13 15:16      
                                    "something" reply      James Brzycki      01/16/13 16:35      
                                 Some links to reduce work       Jim Granville      01/16/13 19:11      
                                 I'm not surprised ...       Richard Erlacher      01/17/13 01:06      
                                    down memory lane      Erik Malund      01/17/13 09:38      
                                       Antique chips        Mahmood Elnasser      01/17/13 10:04      
                                          in my opinion      Erik Malund      01/17/13 13:06      
                                             Just where, under the hood, can you look?      Richard Erlacher      01/17/13 21:42      
                                                this applies equally well      Erik Malund      01/17/13 21:52      
                                                   Did he say he wants apples?      Richard Erlacher      01/17/13 21:57      
                                          Highly integrated devices deprive one of valuable experience      Richard Erlacher      01/17/13 21:38      
                                       the only difference ...       Richard Erlacher      01/17/13 12:14      
                                          a monitor can not       Erik Malund      01/17/13 13:09      
                                             I don't think anyone's that foolish ...       Richard Erlacher      01/17/13 21:15      
                                                I do      Erik Malund      01/17/13 21:26      
                                                   He doesn't have to apply external memory      Richard Erlacher      01/17/13 21:55      
                                                      by your posts he does      Erik Malund      01/17/13 22:14      
                                                         You have to consider ALL his posts      Richard Erlacher      01/18/13 11:47      
            The bible links      James Brzycki      01/14/13 07:47      
               you are right      Erik Malund      01/14/13 08:07      
                  Thanks      James Brzycki      01/14/13 08:29      

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