Overview

This is the Linux BSP (Board Support Package) for the Emcraft Systems STM32F4 System-On-Module (SOM) Starter Kit.

The BSP provides a software development environment for evaluation and development of Linux (uClinux) on the Cortex-M4 processor core of the STM32F4 microcontroller using the Emcraft Systems STM32F4 SOM Starter Kit as a hardware platform.

Supported Features

The following list summarizes the features and capabilities of this release of the STM32F4 SOM Starter Kit BSP:

• Linux:
  • Kernel v4.2;
  • Serial Linux console;
  • Ethernet device driver and Linux TCP/IP networking (ping, NFS, Telnet, FTP, NTPD, etc);
  • WiFi connectivity with security;
  • PPP-based TCP/IP connectivity over GSM/3G modems;
  • Bluetooth support using bluez;
  • busybox v1.17;
  • POSIX pthreads;
  • Hardened exception handling; an exception triggered by a process affects only the offending process;
  • Loadable kernel modules;
  • Secure shell (ssh) and secure copy (scp);
  • Web server;
  • MTD-based Flash partitioning and persistent Flash file system in external Flash;
  • Multi-port serial UART driver;
  • USB Host and Device (widget) device drivers for both the USB HS (High Speed) and USB FS (Full Speed) interfaces;
  • SD Card device driver;
  • I2C master-mode device driver;
  • SPI master-mode device driver;
  • GPIO device driver.
• U-Boot firmware:
  • U-Boot v2010.03;
  • Target initialization from power-on / reset;
  • Runs from the internal eNVM and internal SRAM (no external memory required for standalone operation);
  • Serial console;
  • Ethernet driver for loading images to the target;
  • Device driver for built-in Flash (eNVM) and self-upgrade capability;
  • Device driver for storing environment and Linux images in external Flash;
  • Autoboot feature, allowing boot of OS images from Flash or other storage with no operator intervention;
  • Persistent environment in Flash for customization of target operation;
  • Sophisticated command interface for maintenance and development of the target.
• Development tools:
  • Linux-hosted cross-development environment;
  • ARMv7-optimized GNU toolchain from CodeSourcery (2010q1) is used for development of U-Boot, Linux and user-space applications (toolchain must be downloaded separately from the CodeSourcery web site);
  • Cross GDB for debugging user-space applications;
  • Integration with Eclipse IDE;
  • mkimage tool used by the Linux kernel build process to create a bootable Linux image.

New and Changed Features

This section lists new and changed features of this release:

1. Move STM32F4 SOM to Linux kernel v.4.2.
   ID: RM 137.
2. Merge inittab in uClinux.
   ID: RM 139.
3. Create consolidated rootfs project for STM32F4 SOM.
   ID: RM 142.
4. Merge Emcraft exception-handling code into the baseline kernel.
   ID: RM 149.
5. Port SFTP to uClinux.
   ID: RM 205.
6. Support USB device (gadget) in linux-4.2.
   ID: RM 259.
7. Allow debugging user-space applications using Eclipse IDE.
   ID: RM 262.
8. Enable and validate I2C, SPI, SD Card, UART, GPIO, USB FS/HS Host/Target.
   ID: RM 272.
9. Enable bluez in the rootfs project for STM32F4 SOM.
   ID: RM 275.
10. Add scp and ssh clients.
    ID: RM 305.
11. Enable support for USB WiFi in rootfs.
    ID: RM 308.
12. Support PPP over USB modem.
    ID: RM 342.

Known Problems & Limitations

This section lists known problems and limitations of this release:

1. JTAG debugging rates are limited to 1 KHz.
   ID: RT 101140.
   Workaround: If you require running JTAG at higher frequencies, interrupt the Linux autoboot sequence by resetting the target and pressing any key on the serial console, thus entering the U-Boot command line interface. The Linux kernel is configured to enter a low-power mode by executing a wfi instructions whenever the system enters the so called idle loop (there are no active tasks to execute), which interferes with running JTAG at high-rate frequencies.