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  VS Arduino › › › ATMega328P Downloads Flakey
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Hot Topic (More than 8 Replies) ATMega328P Downloads Flakey (Read 4900 times)
FylB
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ATMega328P Downloads Flakey
Jan 27th, 2022 at 7:59pm
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Hi,
I have a Adafruit CP2104 Friend USB to Serial connected directly to an ATMega328P. Serial streams work and I have DTR connected to the Mega's Reset pin through a .1uF cap in series along with a 10k pullup on the Mega's reset pin.

At first powerup the code downloads and runs fine. The TX and RX LEDs blink nicely. However, if I download again the Mega does not respond. I see the TX LED blinking but no RX LED activity and eventually the Arduino IDE shows the typical avrdude errors.

I have tried several different cables and two different IDEs. Even the Blinky LED sketch fails.

If I unplug the USB cable and power down the circuit, the code will then download and run but further downloads will fail unless I again cycle power.

Whats going on here and how do I fix it please? 

Could it be the Reset pin is not being driven by the right serial pin (in this case DTR)?
  
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Tim@Visual Micro
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Re: ATMega328P Downloads Flakey
Reply #1 - Jan 27th, 2022 at 10:56pm
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Hi

Please follow the guide in the yellow section at the top of this page.

Thanks
  
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FylB
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Re: ATMega328P Downloads Flakey
Reply #2 - Jan 27th, 2022 at 11:13pm
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Here's the debug output.

I'm suspicious that the MCU reset (connected to DTR) is not working.
  
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Tim@Visual Micro
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Re: ATMega328P Downloads Flakey
Reply #3 - Jan 27th, 2022 at 11:48pm
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Thanks. 

1)
To keep things simpler during testing I suggest you changed the configuration name on the tool bar from Debug to Release.

2)
Please open Device Manager and right click COM4 to see the properties. What is the version number of the "Silicon Labs CP210x" driver?

Thanks

  
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FylB
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Re: ATMega328P Downloads Flakey
Reply #4 - Jan 28th, 2022 at 12:06am
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Will do.

Here's the COM4 details
  
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Re: ATMega328P Downloads Flakey
Reply #5 - Jan 28th, 2022 at 12:12am
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Here's the debug output with the config changed to release.
  
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Re: ATMega328P Downloads Flakey
Reply #6 - Jan 28th, 2022 at 12:20am
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If I recall there is a problem with the 10x version of that driver. It is listed as for windows 10 universal but the driver does not provide correct operation. You should uninstall the driver and then install the latest 6x version. You will see a lot of articles on google about the v10.

Please see the note in our FAQ about it alongwith a link to what was the latest 6x and probably still is.

Let's see if that fixes things.



  
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FylB
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Re: ATMega328P Downloads Flakey
Reply #7 - Jan 28th, 2022 at 12:37am
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Tim,
No joy with the 6.7.6 Windows Driver.

What do you think of my supposition that reset is not working correctly?

Phil
  
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Re: ATMega328P Downloads Flakey
Reply #8 - Jan 28th, 2022 at 12:39am
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If you open the serial monitor does clicking the DTR button Off and then On again cause the board to reset?
  
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Re: ATMega328P Downloads Flakey
Reply #9 - Jan 28th, 2022 at 12:48am
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Good idea! I did not think of that.

DTR does NOT toggle with the VM COM port DTR button.
  
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Re: ATMega328P Downloads Flakey
Reply #10 - Jan 28th, 2022 at 2:04am
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When I probe the DTR pin on the USB to Serial module I am not seeing it toggle. I have double checked my wiring and believe it to be correct. How do I get this to work?

I'm sure this type of module is used by many others. If not, then which module do you recommend that works well with VM?
  
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Re: ATMega328P Downloads Flakey
Reply #11 - Jan 28th, 2022 at 2:08am
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Wait a minute. I didn't realize I had to have the COM port connected. Once I did that DTR toggles fine. It looks like DTR is not being controlled programmatically. Is there a setting for this?


« Last Edit: Jan 28th, 2022 at 2:12am by FylB »  
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Re: ATMega328P Downloads Flakey
Reply #12 - Jan 28th, 2022 at 1:28pm
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If you upload using the Arduino IDE does it always work?
  
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Re: ATMega328P Downloads Flakey
Reply #13 - Jan 28th, 2022 at 3:25pm
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No it does not. It’s the same as VM.

What’s the standard circuit to control the Reset pin on an AVR like this?

  
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Re: ATMega328P Downloads Flakey
Reply #14 - Jan 28th, 2022 at 6:49pm
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Ok, I found the problem. It was my reset circuit which consisted of a .1uF cap in series with the CP2104 DTR output to the AVR reset pin. A 10k pullup was also connected to the CP2104 DTR output.

Apparently this is insufficient. So I went over to the arduino.cc site and found the reset circuit for an Uno. I used this to modify my circuit and it now works fine. The revised reset circuit is attached

Thanks for your help.
  
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Re: ATMega328P Downloads Flakey
Reply #15 - Jan 28th, 2022 at 7:02pm
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Thanks for letting us know.
  
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