LinkScope BPU UART Analyzer

Visualizing the Invisible: Real-Time UART Analysis

Debugging serial communication in embedded systems often feels like flying blind. While a standard serial terminal can show you the characters being sent, it rarely provides insight into timing jitter, buffer health, or the exact moment a packet drops. LinkScope BPU UART Analyzer solves this by transforming an ESP32-S3 into a dedicated hardware bridge that captures and streams UART data to a powerful PC-based visualization tool.

Designed for developers working with STM32, ESP32, nRF, and other microcontrollers, LinkScope provides a high-resolution window into your serial streams. By utilizing the native USB capabilities of the ESP32-S3, it achieves stable throughput at high baud rates, making it suitable for modern, data-heavy embedded applications.

High-Performance Hardware Bridge

The project architecture is straightforward yet effective. The target MCU’s TX line is connected to a specific GPIO on the ESP32-S3 (defaulting to GPIO18). The ESP32-S3 acts as a high-speed probe, capturing incoming bytes and encapsulating them using Consistent Overhead Byte Stuffing (COBS). This framing protocol ensures that the binary data can be reliably transmitted over USB to the host PC without losing synchronization, even if the stream contains null bytes or control characters.

Key capabilities include:

• High-Speed Capture: Supports baud rates up to 921600.
• Real-Time Statistics: Monitors throughput, frame counts, and health metrics.
• Protocol Awareness: Uses COBS framing for robust binary data handling.
• Visualization: Includes a real-time throughput graph and a RAW hex inspector.

Getting Started with LinkScope

Setting up LinkScope requires no complex toolchains. The firmware is provided as an Arduino-compatible sketch, allowing for quick deployment to any ESP32-S3 development board.

Firmware Configuration

The firmware utilizes the HardwareSerial class to manage the high-speed input and the built-in USB CDC functionality for host communication. Once the firmware is flashed, the hardware connection is minimal:

Target MCU TX  --->  ESP32-S3 GPIO18 (RX)
Target MCU GND --->  ESP32-S3 GND

Host Analyzer

The PC side of the project features a Windows-compatible standalone executable, though it can also be run directly from source using Python. The analyzer provides a GUI to select the COM port, set the target baud rate, and start the monitoring process. Once connected, the tool offers immediate feedback on the data stream, allowing you to stop, start, and clear the buffer as needed.

Example Implementation

To demonstrate the analyzer’s capabilities, the repository includes example firmware for a target MCU (like an ESP32-WROOM). This example shows how to format packets with magic bytes and CRC-16 checksums to ensure data integrity:

// Example of a formatted packet structure used for testing
struct Packet {
    uint8_t magic[2]; // 0xAA, 0x55
    uint32_t seq;
    char message[10];
    uint16_t crc;
};

By sending these structured packets, users can test the analyzer’s ability to decode frames and detect sequence gaps, which are indicative of hardware or software-induced data loss.

Applications in Embedded Development

LinkScope is particularly useful for scenarios where timing is critical. Whether you are reverse engineering a proprietary protocol, benchmarking the throughput of a new driver, or factory testing production units, the ability to see jitter and packet loss in real-time is invaluable. It bridges the gap between a simple serial monitor and an expensive logic analyzer, providing a software-centric view of serial data health.