Fix bug in baudrate compensation. #44
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
data sheet. The previous code would in effect either apply twice the compensation, or apply no compensation, depending on the polarity of the compensation.
It is now exactly the same as in the documentation. The net result is the same as the previous version.
the right baudrate, then we should use F_CPU, the specified CPU frequency as basis, not the F_CPU with whatever corrections.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The code is now in accordance to the data sheet. The previous code would in effect either apply twice the compensation, or apply no compensation, depending on the polarity of
the compensation.
For how to correctly calculate baudrate compensation, see for instance the megaAVR 0-Series Manual chapter 9.3.4.1
I have verified this by running this program: https://github.com/arduino/ArduinoCore-megaavr/files/3461514/Test_serial_bug.txt
It allows one to verify the exact baudrate with a frequency counter. With the correct code, the error I recorded with my sample was 0,15%. With the original code, 0,3%-