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

[Andre Riesberg]

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