embassy-mcxa: Enable ADRSTALL to avoid drop byte on i2c target.#6437
Open
GBJin wants to merge 1 commit into
Open
embassy-mcxa: Enable ADRSTALL to avoid drop byte on i2c target.#6437GBJin wants to merge 1 commit into
GBJin wants to merge 1 commit into
Conversation
GBJin
changed the title
felipebalbi
approved these changes
Jul 8, 2026
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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
MCXA platform intermittently fails to apply reports, and in the worst case the keyboard is dead.
Root cause: I²C target first-byte drop on the MCXA LPI2C block due to short SCL low span.
SCL stay low for 1.9 us after address match, data drops the first byte.
Enable ADRSTALL (SCFGR1 bit 0, "Address SCL Stall"), refer to MCXAP172M240F70RM_Rev1.pdf section47 LPI2C
This bit is equivalent to SLVPENDING for imxrt platform.
Target will hold SCL low after the address match until MCU reads SASR.
SCL low stretch to 708 us, ready to receive the first byte