REQ-SYS-003: UART communication interface operational

[andre-stefanov]

Requirement Description

REQ-SYS-003: Establish operational UART communication interface as part of the foundational Zephyr RTOS platform setup.

Objective

Implement and verify UART communication functionality on the target hardware platform (MKS Robin Nano STM32F407xx) to enable serial communication capabilities for the firmware.

Technical Requirements

Core UART Functionality

• UART driver initialization in Zephyr RTOS framework
• Serial communication capability at standard baud rates
• Proper UART hardware abstraction layer integration
• Non-blocking/asynchronous UART operations support
• UART interrupt handling for efficient communication
• Buffer management for incoming and outgoing data

Hardware Integration

• STM32F407xx UART peripheral configuration
• Device tree configuration for UART pins on MKS Robin Nano board
• Proper GPIO pin multiplexing for UART TX/RX
• Hardware flow control support (if available)

Communication Interface

• Character-based communication support
• Reliable data transmission and reception
• Buffer overflow protection for incoming data
• Configurable communication parameters (baud rate, parity, stop bits)

Error Handling & Reliability

• UART error detection and reporting
• Communication timeout mechanisms
• Graceful handling of communication interruptions
• UART re-initialization capability on errors
• Proper cleanup on communication failures

Acceptance Criteria

• UART interface successfully initializes during system boot
• Serial communication established at configurable baud rates
• Bidirectional data transmission verified (send/receive)
• Data integrity maintained during transmission
• No data corruption during normal communication operations
• UART operations do not block critical system functions
• Error conditions handled gracefully without system crashes
• Communication interface ready for protocol implementation

Implementation Notes

Zephyr RTOS Integration

• Use Zephyr's UART driver API (uart.h)
• Configure device tree overlay for board-specific UART settings
• Implement UART callback functions for asynchronous operations
• Follow Zephyr coding standards and patterns

Testing Requirements

• Unit tests for UART initialization and configuration
• Hardware-in-the-loop testing on actual MKS Robin Nano board
• Serial loopback tests for data integrity verification
• Performance testing under various load conditions
• Communication reliability testing

Dependencies

• Prerequisite: REQ-SYS-001 (Zephyr RTOS integration functional)
• Prerequisite: REQ-SYS-002 (32-bit microcontroller platform support)
• Prerequisite: REQ-HW-001 (MKS Robin Nano board support functional)
• Enables: Serial communication protocols and interfaces

Implementation Priority

🔴 priority:critical - This is foundational infrastructure required for all serial communication functionality. Communication protocols cannot be implemented without operational UART interface.

Related Files

• boards/mks/robin_nano/ - Board-specific UART configuration
• app/src/ - Application-level UART handling
• tests/ - UART functionality test suites

Definition of Done

• UART communication verified on target hardware
• All acceptance criteria met and tested
• Code review completed
• Unit and integration tests passing
• Documentation updated