ATmega1284P external quartz configuration - need help with settings for quartz crystal at 16MHz

[andeug]

Hi,

I am using an ATmega1284P in one of my projects, and when configuring it, I cannot find the option for an external 16MHz quartz crystal.
Can someone please tell me where that setting is and what I should choose? I am speaking of "Step 5 - Chip Configuration / Select clock source".

Thank you,
Andreas

[chipfryer27]

Hi

I'm not overly familiar with ATmega but it looks like you will need to:-

Step-4 Project Options set Clock Speed to 16MHz as this tells Flowcode what speed you are running. Very important to set correctly.
Step-5 Chip Configuration. I would choose last option as this is for 8MHz and above (as far as I am aware). You may get away with a lower than 65ms startup time depending on your crystal, but this may be safest option to start with

Screenshot 2026-02-14 133129.jpg (43.22 KiB) Viewed 165 times

To check, run a one-second flasher.

Hope this helps.

[andeug]

Thank you, I will give it a try in a few days when I receive the electronic components.

[chipfryer27]

Hi

I might have a "Mega" lying around somewhere. Offhand no idea which version but if I find it I'll check.

Regards