-
-
Notifications
You must be signed in to change notification settings - Fork 1.1k
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
Don't waste RAM in the low-level TWI Wire driver #520
Open
dewhisna
wants to merge
1
commit into
arduino:master
Choose a base branch
from
dewhisna:LessTWIRAM
base: master
Could not load branches
Branch not found: {{ refName }}
Loading
Could not load tags
Nothing to show
Loading
Are you sure you want to change the base?
Some commits from the old base branch may be removed from the timeline,
and old review comments may become outdated.
Conversation
This file contains 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
The TWI Master Read/Write functions are blocking anyway, so why copy it to a local buffer first? It wastes memory, plus limits transmission size to the buffer size.
Memory usage change @ 92efe52
Click for full report table
Click for full report CSV
|
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Outdated suggestions cannot be applied.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.
This originated on MCUdude/MiniCore#245
Since
twi_readFrom()
andtwi_writeTo()
are both blocking functions, there is no need to allocate a specialtwi_masterBuffer
. Doing so wastes valuable RAM, uses extra time to copy the data to the secondary buffer, and limits the transfer size toTWI_BUFFER_LENGTH
. Instead, it only needs a pointer to the buffer for the IRQ to use for the transfer.And, if asynchronous non-blocking functions are ever added, which will require a different API and callbacks, etc., then the existing
txBuffer
andrxBuffer
for slave mode can just be used there too, since master mode and slave mode can't both be active at the same time.This frees nearly 32 bytes of RAM per TWI port, which is huge on a micro that only has 2K of RAM and you are down to counting every available bit for your application.