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???
01/16/13 23:30
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#189205 - Extra modes ?
Responding to: ???'s previous message
Koen De Ganck said:
- the ALE pin is toggling and the (external) X-tal runs, even if not started up
- resetting after a good start-up works fine
- I have a bootloader which toggles a pin with LED, so I can check it easily
- I do not see a big difference in using LM810 or not, only the reset pulse length is different ( 16ms <> 200ms )
-the X-tal is used just for internal clocking

I have a (older) P89C51RD (NXP) as reference in the same board and same power supply,
and it always starts correctly in any situation.

I have no clue what is going wrong.


If re-reset is always ok, it maybe one of the extra modes you are hitting ?

Do you have any loads on PSEN, or the OCD pins ?
ie The SW-Boot force mode, involves holding PSEN Low, on RST release

To check this, is you have a serial link, send the unit a 'U'
The inbuilt bootloader will echo 'U' as it auto-bauds.

List of 24 messages in thread
TopicAuthorDate
Reset issue with new Atmel AT89LP51ED2            01/01/70 00:00      
   Do never use a µC from which only a preliminary...            01/01/70 00:00      
      configuration settings            01/01/70 00:00      
         what about negative reset?            01/01/70 00:00      
            good idea but            01/01/70 00:00      
   Some things to check...            01/01/70 00:00      
      also try no LM810 at all            01/01/70 00:00      
         reset is inverted            01/01/70 00:00      
      no strange signals            01/01/70 00:00      
         Extra modes ?            01/01/70 00:00      
            pull-up on PSEN solves the problem            01/01/70 00:00      
               small capacitor ?            01/01/70 00:00      
                  small capacitor            01/01/70 00:00      
   side-stepping the problem?            01/01/70 00:00      
      SST could be an option            01/01/70 00:00      
   final status AT89LP51ED2 reset            01/01/70 00:00      
      Clarifies             01/01/70 00:00      
         loads on PSEN            01/01/70 00:00      
            An isolated PSEN works fine ?            01/01/70 00:00      
               GAL causes problem            01/01/70 00:00      
                  ATF16V8CZ has Pin-keeper            01/01/70 00:00      
                     'Z' indeed            01/01/70 00:00      
                        ATF16V8BQL has Icc of ~1.5mA            01/01/70 00:00      
                           'BQL' version could be an option            01/01/70 00:00      

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