AVR won't run without programmer attached

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Hi guys,

Here is part of the schematic that I am using for a project. I built the hardware and sent it to my partner to program. He tells me that the hardware will not run if the programmer is not plugged into the ISP port. The only thing that I can come up with is that maybe I don't have permanent power to a pin on the AVR that needs it. If you have any suggestions please let me know.

Thanks for any advice,
J

 

martin-h said:
Try to use pull-up resistor on /RESET pin. Old and small ATtiny15 needs one too. I never used ATmega128 but I googled for some schematics and everyone there's a pull-up on /RESET pin.

for example: ATmega128 ISP-Pins beschaltung - Mikrocontroller.net
Click to expand...

OK thanks a lot! We will give it a try. That makes sense since the datasheet says:

"RESET: Reset input. A low level on this pin for longer than the minimum pulse length will generate a
reset, even if the clock is not running. The minimum pulse length is given in Table 19 on page
50. Shorter pulses are not guaranteed to generate a reset."

Sounds like we are stuck in reset mode until the programmer is plugged in which I guess pulls that pin high.
 

If you check page 318 of the mega128 it says "Reset pull-up resistor 30K-60K", this this is an internal pull-up resistor.
To verify this you can also check page 359 graph 212 which is the internal reset pull-up current vs reset pin voltage
You can still try to use an external resistor but i doubt that this will solve your problem.

The last time you were asking for this circuit you didn't have a problem like this, what have you changed since then in the hardware?

Alex
 

Hi Alex,

Thanks for the info on the datasheet. The quote I posted from the datasheet was actually from the summary sheet. I didn't have the main datasheet available so I will give that information to my programmer. We haven't changed anything, my programmer just never said anything about it to me until this past weekend. Guess he was to busy with the programming to relay that important bit of info to me! hahaha

I appreciate the help!
J
 

You say that your circuit works only when the programmer is connected, this is not clear, you mean that it can be programmed but what happens when you remove the programmer and you say that it doesn't work.
Can it be a software (program code) problem?
Try a simple program to turn on/off a pin and measure the pin to see if it executes .

Alex
 


What I got from him was that it executes and behaves properly as long as he leaves the programmer plugged into the ISP. As soon as he removes it, the hardware no longer functions, so no led's flash and so on. He has the led's flashing and the menu working on the LCD, just apparently not when the programmer is not plugged into it.

Make any sense?
 

Does it turn off completely, can it be power related?

Alex
 

Not sure on that Alex, I will ask him. I have a second prototype that I just got put together for testing FW so as soon as I can get him to send me a copy of the FW I can give you more information on exactly how it's behaving. Also we can see if it's a design problem, or just something on his prototype.

J
 

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