Programming - Can read but can't write

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metRo_
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#1
Posted by metRo_: Thu. May 29, 2014 - 11:39 AM
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Hi,
I'm programming a Atxmega8E5 on my own board. The Avr Dragon can read, it says that can write but when verify it fails so I think it is not writing to the flash.

Since it has only one line to read/write it is odd :s

Where should I look to problems?

EDITED:
Put the multimeter probes between ground and reset to see if it goes gnd and with the probe on that lines it can program :s

EDITED2:
Remove the 10kohms resistor like in the xmegaE5 xplained board but it only with the multimeter probes on it I can program it.

EDITED3:
Only a multimeter probe on reset line is suficient so without it the reset line should be floating?

Now it the R1-10k was removed.

Tags:

AVR Microcontrollers, AVR XMEGA
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DocJC
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Posted by DocJC: Thu. May 29, 2014 - 04:02 PM
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Your schematic looks fine.

There are many Threads about Dragon and Xmega problems. It works fine for some people, not for others. It has never worked reliably for me.

The Atmel AVR ISP mkII is a programmer only, no debug capabilities, but it works great.

The Xmega's original data sheets stated that there should be NO resistor or cap tied to the two lines needed for PDI programming. They must both have the same impedance. If you feel you need an external reset circuit, then you should consider a jumper / Header, etc., so that you can have nothing connected during project development, and then connect it when you are done with all of your programming.

You might consider putting a small series resistor in line for your Analog Vref A signal. Hard wiring it to Vcc isn't a problem as long as thepin is ONLY an input. If you ever make a mistake in your code and make it an output, low, it will directly short Vcc to Ground. This will crash the program, and may burn out the pin. As the ADC draws very little current, a series resistor and a cap to ground ought to work fine for this, and it will "protect" your hardware from possibly destroying itself. This, however, has nothing to do with the Dragon problem.

JC

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metRo_
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Posted by metRo_: Thu. May 29, 2014 - 04:31 PM
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Thank you for the AVref note.

The strange is that if I put something in the reset line it starts working. Right now invest in another programmer is not something I can do.

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