Development Environment ======================= Hardware -------- For development, it is highly recommended to have JTAG/SWD debugger. For boards with DFU (Device Firmware Upgrade) feature (such as DfuSe), it is possible to develop with that. But it should be considered *experimental* environment, and it should not be used for usual purpose. That's because it is basically impossible for DfuSe implementations to disable reading-out from flash ROM. It means that your secrets will be readily extracted by DfuSe. For JTAG debugger, Olimex JTAG-Tiny is good and supported well. For SWD debugger, ST-Link/V2 would be good, and it is supported by tool/stlinkv2.py. OpenOCD ------- For JTAG/SWD debugger, we can use OpenOCD. GNU Toolchain ------------- You need GNU toolchain and newlib for 'arm-none-eabi' target. In Debian, we can just apt-get packages of: gcc-arm-none-eabi, binutils-arm-none-eabi, gdb-arm-none-eabi and libnewlib-arm-none-eabi. For other distributiions, there is "gcc-arm-embedded" project. See: https://launchpad.net/gcc-arm-embedded/ We are using "-O3 -Os" for compiler option. Building Gnuk ------------- Change directory to ``src``: $ cd gnuk-VERSION/src Then, run ``configure``: $ ./configure --vidpid= Here, you need to specify USB vendor ID and product ID. For FSIJ's, it's: --vidpid=234b:0000 . Please read the section 'USB vendor ID and product ID' in README. Type: $ make Then, we will have "gnuk.elf" under src/build directory.