Serial Upload Issues on Internal Clock ATmega328p-au

I've been prototyping a new PCB for a little project of mine and due to size restrictions, I wanted to use the internal clock. However, I'm now having serial issues, I can read the serial monitor perfectly fine, but i can't upload sketches to the device. I have the fuses set correctly, and have received help from this forum a couple of weeks ago informing me of why this issue is around.

A couple of questions:

  • The current settings to upload to the board are set using a speed of: 57600, would lowing this down to say 9600 have a chance to sort my issue out?
  • Is the default bootloader or the optiboot varient for the atmega328 usable as it is if i just change the speed in the boards.txt file?

samuel235: The current settings to upload to the board are set using a speed of: 57600, would lowing this down to say 9600 have a chance to sort my issue out?[/li][/list]

depending on a particular chip using internal clock for serial can be problematic. osccal tuning may be required. baud rate dont matter in this case because 4% error is 4% error regardless.

fyi 57k is my personal favorite. slower is... well... slow. faster and there can be problems with cable length, noise, or capacitance.

Right okay, so you're saying that the only stable way to use serial upload is to use an external crystal?

If so, for power consumption, i'm sleeping the module by the way, would you go with 8MHz or 16MHz external?

crystal is not the only way. as mentioned tuning osccal works too but is much more trouble and not as stable. for battery operation i use 8mhz xtl sometimes but usually prefer 16mhz because easier to find, slightly less power, and half the price (3 cents instead of 6 cents, lol). however i hardly ever use caps with those.

Hmmmkay. I think I'm going to use these along with two 8pF caps with it. What is your opinion on this, does this sound okay?

those are very nice. i use similar when space is an issue. pricey but only way to fit inside a socket or between 2 pins. be careful not to drop it on the floor. lol.

make sure to use the right pads because 2 of those are shorted (case/gnd) and do not go to quartz.

I'm currently soldering 0603 parts relatively easily now, my soldering skills are developing ;) I'm about to enter the trials of drag soldering now.

But yes, thank you for confirming this for me!

samuel235: I'm currently soldering 0603 parts relatively easily now

It would be fun for us if you return to this thread and upload a photo of your finished board.

I’m currently working on battery/voltage level monitoring to indicate to me when the battery needs changing. This is all part of a custom home automation project. This will relay information back to my controller via a gateway and then i can have the home automation controller act accordingly to the voltage levels, things like mobile push notifications or emails.