MayaPosch / BSICS-SVR

BSICS-SVR

BSICS-SVR a C++ firmware project implementing an ethernet-connnected controller for custom Test&Measurement Equipment.

Basic characteristics

• uses a STM32 Nucleo-F767ZI board (optionally Nucleo-F746ZG)
• 100Base-TX ethernet interface with LAN8742A PHY
• uses FreeRTOS (CMSIS-RTOS v1 API), LwIP
• CLion (CMake) project
• SCPI server (default port 5025) via libscpi
• todo: webserver for setup, control and graphing (websockets, flot charts)

See "UM1974 STM32 Nucleo-144 boards (MB1137) 8.0" (available at https://www.st.com/en/evaluation-tools/nucleo-f767zi.html#documentation) for "Hardware Layout and Configuration".

Warnings

This project uses several rudimentary starting points which come with their own challenges. It is created as a new project for the Nucleo-F767ZI board, generated and configured using STM32CubeMX and appended by creating and copying files to a tidied-up project structure.

Changes and additions are made in an attempt to clean up the project and address known memory- and RTOS-specific issues.

• the scpi-parser project kindly provides an SCPI server example which does not claim to be authoritative, just a convenient starting point. libscpi is not thread-safe - it requires a dedicated thread, the communication with which is queue-based.

• The ST-provided LwIP_HTTP_Server_Netconn_RTOS code example is outdated and contains fundamental flaws. It's unclear whether these are fixed at the time of this writing.

• STM32CubeMX middleware can be assumed to contain bugs, thread-safety issues and memory protection / memory layout issues.

• ST-related ethernet issues (memory layout and MPU configuration, caching, LWPI API, ...) are tracked at https://community.st.com/s/question/0D50X0000BOtfhnSQB/how-to-make-ethernet-and-lwip-working-on-stm32 , which is an excellent place to start (read: being thrown in at the deep end).

In the text below, project creation and composition are documented, along with the necessary attempts to resolve issues identified. The LwIP_HTTP_Server_Netconn_RTOS example was opened side-by-side and STM32CubeMX was used to create an editable project file which wasn't provided with the server example. ST notes the example is currently not compatible with (= outdated) CubeMX.

The author does not claim to be an expert and code is provided as-is. Corrections and suggestions are always welcome.

The T&M Device Server Project

Project Structure

• Applications/
  • SCPI_Server
• Drivers/
  • BSP, CMSIS, HAL_Driver
• Middlewares/Third_Party/
  • FreeRTOS, libscpi (libscpi.a + headers), LwIP
• Src/
• Inc/
• startup/

In-Depth Topics

• Basic project creation with CLion and STM32CubeMX
  • Introduction to the Cortex-M7 MPU
  • Modifications for Thread Safety (newlib)
• debug ouput via USART and virtual COM port
• establishing and testing ethernet functionality
  • keep-alive mechanism to automatically close connections when client does no longer respond
• adding libscpi
• I2C device support