The OSPI PHY Grapher: Real-Time Data Visualization Over UART for Smarter Flash Tuning

OSPI PHY tuning is a critical step in bringing up flash memory on modern SoCs, but the tuning datasets (81.9 KB per sweep) remain opaque to developers, making hardware bugging difficult and time-consuming.

While conventional approaches rely on command-line tools and manual interpretation of raw data, the lack of visibility into multi-dimensional tuning results (5×128×128 pass/fail arrays) makes it difficult to identify optimal tuning points and understand corner cases. Developed a new superior diagonal-based search tuning algorithm, combined with radial validation around tuning points, this approach systematically selects naturally stable regions that avoid noisy unstable zones. Unlike traditional window-based methods that require maintaining fixed search windows and periodic revalidation, the diagonal approach eliminates this maintenance burden while delivering a more robust and stable tuning solution.

In this talk, we present our work on integrating OSPI PHY tuning with FreeRTOS on TI Sitara platforms. We developed an end-to-end solution that automates the capture, transfer, and visualization of PHY tuning data from embedded devices to host systems. Unlike traditional approaches that required placing the device in semi-host mode, we leverage XMODEM1k with CRC-16 validation over UART for reliable firmware-to-host communication, enabling efficient transfer of large datasets without blocking real-time tasks. Our modular architecture abstracts device-side sweep collection from the transfer protocol, allowing flexible
integration with different RTOS configurations.

The session will cover the complete debugging workflow, including device-side PHY sweep execution, protocol design trade-offs, reliable data transfer, and visualization for failure analysis. We demonstrate how 2D heatmaps reveal failure zones and marginal tuning points invisible in raw data. By decoupling data capture from visualization, our framework makes hardware debugging reproducible across teams and SoC variants, while design patterns (async UART handling, pre-allocated buffers) are applicable to any MCU-to-host communication use case—from OTA updates to sensor data streaming.