[En-Nut-Discussion] Could not enter programming mode

[Daniel]

Daniel wrote:

>Andre Riesberg schrieb:
>  
>
>>Daniel wrote:
>>
>>  
>>    
>>
>>>Hi.
>>>
>>>While I was programming my Ethernut 1.3 with stk500.exe, I had 
>>>connected SCK (SPI Bus Serial Clock) to GND. After that I read, that 
>>>I must not do that.
>>>Now stk500.exe tells me, that the controller "Could not enter 
>>>programming mode".
>>>
>>>Any advise how to fix it up?
>>>
>>>Thanks,
>>>Daniel
>>>_______________________________________________
>>>http://lists.egnite.de/mailman/listinfo/en-nut-discussion
>>>
>>>
>>> 
>>>
>>>    
>>>      
>>>
>>Hi Daniel,
>>
>>do you pull the SCK signal to GND only on the programmer or on cpu or 
>>on both?
>>
>>Do you have disconnected all power supplys and start again?
>>
>>Please make some tests:
>>First, disconnect programmer and CPU.
>>
>>- Check the SCK signal at the programmer: In normal condition (no
>>programming) the signal must be on high level.
>>- Check the SCK signal at the CPU board. Normally you see a low level. 
>>With a 10k resistor to +5V you can pull this signal to high level.
>>- With still disconnected board try to start programming (I use 
>>avrdude). With a scope you can see (for a short time) a lot of pulse 
>>on the SCK line.
>>
>>Does this work?
>>
>>Greeting
>>Andre
>>
>>
>>
>>
>>
>>
>>_______________________________________________
>>http://lists.egnite.de/mailman/listinfo/en-nut-discussion
>>
>>  
>>    
>>
>
>Hi Andre, thanks for the answer.
>
>Here are the results of the tests you mentioned:
>
>- SP Duo 2 Programmer, only supported with Vcc & GND, not connected to
>CPU: SCK (PB1) is low
>    When I start programming, I see a short low voltage at SCK. 
>Unfortunately I doesn't have a scope, only a voltmeter.
>    You say, the signal must be on high level. It's low. But I can 
>program my second Ethernut with this SP Duo without problems.
>
>- CPU, not connected with SP Duo 2: SCK (PB1) is low
>    Should I try to pull the SCK line high, when I connect the 
>programmer to the CPU?
>
>
>Daniel
>_______________________________________________
>http://lists.egnite.de/mailman/listinfo/en-nut-discussion
>
>
>  
>
Hi Daniel,

see my commends:

- SP Duo 2 Programmer, only supported with Vcc & GND, not connected to
CPU: SCK (PB1) is low
** Could be ok. I have no schematics from this programmer.
    When I start programming, I see a short low voltage at SCK. 
Unfortunately I doesn't have a scope, only a voltmeter.
** That's makes it a little complicated......
    You say, the signal must be on high level. It's low. But I can program
my second Ethernut with this SP Duo without problems.
** Ok. I think the programmer is no defect.

- CPU, not connected with SP Duo 2: SCK (PB1) is low
    Should I try to pull the SCK line high, when I connect the
** Try it with 10k! You have a second board, try to compare the signals on
the two board.

programmer to the CPU?

Greetings
Andre





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Hi Andre,

Both Ethernuts have a low SCK line. Both programmers I've tested have a low
SCK line. One Board and both programmers work. Only on one board, the
programmer cannot enter the programming mode.
Even with SCK, pulled to high via 10k it doesn't work.

Daniel