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Clear Z flag before leaving sda_low #324

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Clear Z flag before leaving sda_low #324

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jburks
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@jburks jburks commented May 22, 2022

This PR fixes #323 by ensuring Z flag is clear when returning from sda_low.

Tested on hardware where RTC could not have its time set on r41; RTC time changes (e.g. TI$="235959" from BASIC) correctly take effect after this change.

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jburks commented May 22, 2022

This also seems to fix #310 on my hardware.

@mist64 mist64 closed this in cff622e May 22, 2022
mist64 added a commit that referenced this pull request May 22, 2022
@mist64
[KERNAL] fixed I2C writing
933054a 
An earlier optimization used the `tsb` instruction, which activated
a sleeping bug, where writing to an I2C device evaluated the Z
flag after sending 8 bits and receiving the ACK instead of the C
flag.

With this fix, smc_set_activity_led can be turned on again.

Fixes #324
Fixes #310
@jburks jburks deleted the i2c_write_fix branch May 22, 2022 20:47
gaekwad pushed a commit to gaekwad/x16-rom that referenced this pull request Nov 30, 2024
@mooinglemur
[KERNAL] comment cleanup, remove unused macros (commanderx16#324)
3de280b
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Successfully merging this pull request may close these issues.

Cannot set RTC due to Z flag semantics in i2c_write
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@jburks