Software Compilation

Software Compilation

See software design for more details on the actual software

Compilers

This is just some background methods on getting arm-elf-gcc, newlib etc. installed.

Mac OSX

See Wim's gist for compiling arm-eabi-gcc

Ubuntu x86/x86_64

Wim's gist might also work here. Else we can always fall back to gcc4.0.2 binaries found on GNU ARM

You'll likely need to use --with-system-zlib when configuring gcc.

Note: The version in apt called arm-linux-eabi-gcc is not what we want. What this compiler is for is when you want arm binaries to run on a arm based platform with a Linux OS. What we have is no OS so want binaries that run on bare metal.

Also use Wim's gist

Building

In the Software directory run make. This produces 5 elf files in the build directory, one for each board.

Programming and Debugging

For both programming and debugging we are using a combination of OpenOCD and arm-eabi-gdb.

The first step is to connect OpenOCD to the MCU, simply connect the USB-JTAG adaptor to your USB and the JTAG header on the board then open a new terminal in the Software directory and run make ocd. This will start up OpenOCD with the correct default settings.

Getting OpenOCD working on OS X

Based on information from the SparkFun forums

The easiest way to install OpenOCD is if you're using Homebrew. Simply brew install openocd. It's likely included in MacPorts and Fink as well. Alternatively you can just install libftdi, libusb and OpenOCD from source.

You'll probably want to be using USART on your programmer as well, assuming it's an FTDI2232 based programmer just install the FTDI Virtual COM Port Driver. Unfortunately this steals the JTAG part of the programmer and makes it appear as a serial port as well stopping OpenOCD from using it.

To fix this you simply need to edit the list of interfaces that it will auto-mount in /System/Library/Extensions/FTDIUSBSerialDriver.kext/Contents/Info.plist and remove the A section of the programmer that you're using. The Universities programmers are listed as FT2232C so delete the FT2232C_A section, lines 1791-1807 as of version 2.2.16 of the driver. If you're using a different programmer then convert the VID and PID to a decimal number and find the section with the corresponding idVendor and idProduct and delete that A section.

To check if this has worked either reload the driver:

sudo kextunload /System/Library/Extensions/FTDIUSBSerialDriver.kext
sudo kextload /System/Library/Extensions/FTDIUSBSerialDriver.kext

or just unplug and replug the programmer, then check which virtual COM ports have appeared with ls /dev/tty.usb*

Programming

To just program the MCU run

make program-<BINARY_NAME>

where <BINARY_NAME> is the basename of the binary you want to program, e.g.

make program-sensor

to program the sensor board.

Debugging

To debug the program in GDB run

make debug-<BINARY_NAME>

where <BINARY_NAME> is the same as above. This will connect GDB to OpenOCD, reset the MCU, program the binary then drop you into a GDB shell with the MCU halted at the resetHandler.

Basic GDB commands

The [] are not parts of these commands, they indicate optional parts of the command, e.g. info registers is written i[nfo] r[egisters], this means the command i r will do the same thing.

The simplest command required is

c[ontinue]

this simply resumes the MCU from the current program counter and runs it until you hit ^C.

To step through the program you can use

step

to step a function at a time or

stepi

to step an instruction at a time.