[YashAnand69]

The CircuitPython-compatible UART defaults to parity=None, but its constructor reads parity.value unconditionally. Default construction and the supported nine-bit/no-parity configuration therefore fail with AttributeError after setting the baud rate.

Apply the parity offset only when parity is supplied. This preserves the existing eight- and nine-bit no-parity modes, explicit even/odd parity, stop-bit encoding and older-firmware fallback. The regression tests check the actual command sequence and restore the cached UART configuration between cases.

Validation: five no-parity regressions fail on unchanged main; all 11 focused cases and 34 available tests pass with the fix. Configured source Black, Flake8, Bandit and pydocstyle, wheel/sdist builds and Sphinx documentation pass (seven existing documentation warnings). Scoped busio coverage increases with the same test selection. No physical PSLab or complete hardware integration run is claimed.

Prepared with Codex assistance; the change and command-level regressions were reviewed against the current firmware mode encoding.

Summary by Sourcery

Fix UART configuration to handle absent parity while retaining existing mode validation and encoding behavior.

Bug Fixes:

• Allow CircuitPython-compatible UART construction with omitted parity, including default and nine-bit configurations.
• Preserve UART mode handling for explicit parity, stop-bit combinations, and older firmware fallback.

Tests:

• Add hardware-independent regression coverage for UART parity, stop-bit, firmware fallback, and invalid nine-bit parity configurations.

Summary by CodeRabbit

• Bug Fixes
  • Fixed UART configuration for connections that do not use parity, including default and nine-bit modes. Existing even and odd parity configurations remain supported.

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[sourcery-ai]

Reviewer's Guide

Fixes CircuitPython-compatible UART construction with the default parity=None by conditionally applying the parity mode offset, while adding mocked command-level regressions covering no-parity, explicit parity, stop bits, nine-bit validation, cached configuration, and older firmware.

Flow diagram for UART parity mode encoding

flowchart TD
    A[UART construction] --> B[Set baud rate and base mode]
    B --> C{parity is None}
    C -->|Yes| D[Keep base mode unchanged]
    C -->|No| E[Add parity.value offset]
    D --> F[_set_uart_mode]
    E --> F
    F --> G[UART configured]

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File-Level Changes

Change	Details	Files
Guard parity encoding so no-parity UART configurations do not dereference a missing enum value.	Apply the parity offset only when an explicit parity option is provided. Preserve existing stop-bit, data-width, explicit even/odd parity, and older-firmware behavior.	pslab/bus/busio.py
Add hardware-independent regression coverage for UART mode encoding and configuration side effects.	Verify default and nine-bit no-parity command sequences and cached mode state. Verify stop-bit combinations, explicit parity combinations, nine-bit parity rejection, and older-firmware fallback. Restore process-wide cached UART configuration between tests.	tests/test_busio_uart_configuration.py

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: 0aa03108-4da9-49a7-a3e7-7bfe70df6c08

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📥 Commits

Reviewing files that changed from the base of the PR and between 08de0d0 and cb2ac29.

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📒 Files selected for processing (2)

• pslab/bus/busio.py
• tests/test_busio_uart_configuration.py

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Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 3 remain after this review.

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📝 Walkthrough

Walkthrough

UART initialization now adds parity configuration only when a parity value is supplied. New mocked tests cover no-parity configurations, parity encodings, older-firmware behavior, and invalid parity with nine data bits.

Changes

UART Configuration

Layer / File(s)	Summary
UART parity configuration and regression tests pslab/bus/busio.py, tests/test_busio_uart_configuration.py	UART.__init__ adds the parity value only when parity is supplied. Mocked tests cover no-parity mode encoding, even and odd parity, older-firmware behavior, and rejection of parity with nine data bits.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

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Merge Risk: ⚪ Minimal · up to cb2ac

No actionable merge risk remains from the reviewed UART changes; merge after normal checks.

Pre-merge checks | 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely identifies the main change: fixing CircuitPython UART construction when no parity is provided.
Docstring Coverage		Docstring coverage is 85.71% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 2 files.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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