Raspberry Pi

Raspberry Pi Based Projects

• Raspberry Pi minimal components DC motor servo control
• The small robotic arm control with use of Simulink CAN blocks with ERT Linux target

GNU/Linux Kernel and other Utilities

• fully-preemptive Linux kernel for RPi
• read-only root + overlay and U-boot with DTS

GCC Tool-chain for Cross-Compilation

There are more suggestion of different arm-gnueabihf toolchains variants to use for cross-build of applications for Raspberry Pi platform. But all of them which I have easily found do not correctly match ARMv6 BCM2835 target. The unfortunate selection of arm-linux-gnueabihf as GNU triplet for Raspbian build clashes with official arm-linux-gnueabihf tool-chains which target ARMv7 architecture and produced binaries are less or more incompatible with RPi hardware and GLIBC build.

I have decided to define separate/non-classing GCC architecture arm-rpi-linux-gnueabihf variant and use original Raspbian GLIBC binaries to ensure best compatibility for build tool-chain. The simple approach is to put whole Raspbian root filesystem copy to /usr/arm-rpi-linux-gnueabihf/sys-root. The mosts of the files are not required in fact so reduction to subset of /lib, /lib/arm-linux-gnueabihf, /lib/arm-linux-gnueabihf/libnfsidmap, /lib/arm-linux-gnueabihf/security, /usr/include, /usr/lib, /usr/lib/arm-rpi-linux-gnueabihf is enough. Other option is to use debootstrap with correct parameters to install base Raspbian libraries and development files in /usr/arm-rpi-linux-gnueabihf/sys-root directory. Some symbolic links has to be adapted to point correctly to target files by changing paths to relative. Then libc.so prepared for relative paths and cross-compilation needs to be provided. Create file /usr/arm-rpi-linux-gnueabihf/lib/libc.so with next content

/* GNU ld script
  Use the shared library, but some functions are only in
  the static library, so try that secondarily.  */
OUTPUT_FORMAT(elf32-littlearm)
GROUP ( libc.so.6 libc_nonshared.a  AS_NEEDED ( ld-linux.so.3 ) )

This should be enough for environment for standard binutils and GCC build. binutils-2.24 has been used without any changes. gcc-4.9.1 with statically included gmp-5.1.2, mpc-1.0.1 and mpfr-3.1.2 has been patched by subset of Debian patches

alpha-no-ev4-directive.diff
boehm-gc-getnprocs.diff
note-gnu-stack.diff
gcc-target-include-asm.diff
pr57653.diff
pr61046.diff
pr61336.diff
gcc-setmultilib-fix.diff
pr61841.diff

Then binutils and GCC has been compiled and installed with next configuration

../../../src/gcc-4.9/configure -v \
        --enable-languages=c,c++ \
        --prefix=/usr \
        --with-system-zlib \
        --without-included-gettext \
        --enable-threads=posix \
        --enable-shared \
        --disable-nls \
        --enable-clocale=gnu \
        --enable-objc-gc \
        --enable-mpfr \
        --enable-tls \
        --enable-secureplt \
        --enable-targets=arm-linux-gnu \
        --enable-symvers=gnu \
        --enable-checking=release \
        --build=x86_64-linux-gnu \
        --host=x86_64-linux-gnu \
        --target=arm-rpi-linux-gnueabihf \
        --enable-version-specific-runtime-libs \
        --disable-libgomp \
        --with-headers=/usr/arm-rpi-linux-gnueabihf/sys-include \
        --with-sysroot=/usr/arm-rpi-linux-gnueabihf/sys-root \
        \
        --enable-linker-build-id \
        --enable-libstdcxx-time=yes \
        --enable-gnu-unique-object \
        --enable-plugin \
        --enable-multiarch \
        --disable-sjlj-exceptions \
        --with-arch=armv6 \
        --with-fpu=vfp \
        --with-float=hard

The build binaries for x86_64/amd64 Debian based systems are provided in our DEB tool-chains collection

* http://rtime.felk.cvut.cz/debian/pool/main/b/binutils-2.24/binutils-arm-rpi-linux-gnueabihf_2.24-1_amd64.deb
* http://rtime.felk.cvut.cz/debian/pool/main/g/gcc-4.9.1/gcc-arm-rpi-linux-gnueabihf_4.9.1-1_amd64.deb

Raspberry Pi JTAG debugguing

* RPi JTAG setup documentation http://sysprogs.com/VisualKernel/tutorials/raspberry/jtagsetup/

U-boot commands to enable JTAG pins

mw.l 0x20200000 0x04a020
mw.l 0x20200008 0x65b6c0

FTDI2232 JT_USB5 RPi Connection and Configuration

Interconnection of 10 pin JT_USB5 cable to RPi P1 connector

JT_USB5 pin	Signal	RPi P1	Type	Description
1	TCK	22	Out	Clock Signal Output
2	VREF	1	Out	Target voltage reference 3.3 V
3	TDI	7	Out	Serial Data Out
4	RTCK	16	In/Out	General Purpose I/O
5	TDO	18	In	Serial Data In
6	RST	NC		Reset
7	nTRST	15	In/Out	Test system reset
8	GND	6, 9, 25	In/Out	Target ground
9	TMS	13	Out	Select Signal Out
10	GND	6, 9, 25	In/Out	Target ground

telnet_port 4444
gdb_port 3333

interface ftdi

#ftdi_device_desc "Dual RS232"
ftdi_vid_pid 0x0403 0x6010

ftdi_layout_init 0x0cf8 0x0cfb
ftdi_layout_signal nTRST -data 0x0010 -noe 0x0800
ftdi_layout_signal nSRST -ndata 0x0040 -noe 0x0400

ftdi_layout_signal nTRST -data 0x0010
ftdi_layout_signal nSRST -ndata 0x0040
ftdi_layout_signal LED -ndata 0x0800

transport select jtag

adapter_khz 500

reset_config none

if { [info exists CHIPNAME] } {
   set  _CHIPNAME $CHIPNAME
} else {
   set  _CHIPNAME raspi
}

reset_config none

if { [info exists CPU_TAPID ] } {
   set _CPU_TAPID $CPU_TAPID
} else {
   set _CPU_TAPID 0x07b7617F
}
jtag newtap $_CHIPNAME arm -irlen 5 -expected-id $_CPU_TAPID

set _TARGETNAME $_CHIPNAME.arm
target create $_TARGETNAME arm11 -chain-position $_TARGETNAME

adapter_khz 500

init