Semihosting is a technique to do printf() debugging through an active debug connection. So instead using a physical connection like RS-232 or USB CDC, the connection to the host machine is through the debugger. This post is about enabling and using semihosting with gcc and newlib/newlib-nano in Freescale Eclipse based Kinetis Design Studio (KDS) using the GNU ARM Eclipse plugins.
Semihosting Console View with output
Many applications need to store persistent (non-volatile) data at runtime: configuration data, error logs, sensor data, calibration values, etc. The question is: where to store that data? If it is only a few kBytes, an SD card or similar is an overkill. Adding an external EEPROM? Sure, that works, but adds an extra part to the design. Some microcontroller have internal EEPROM. But what if not? Why not using the microprocessor internal flash memory?
Internal FLASH vs. external EEPROM
Many times I start with a project and tutorial, only to get interrupted for emergency tasks and assignments. For a long time I wanted to add GPS (Global Positioning System) functionality to one of my projects. While I started a few months ago on this, it took me until this week-end to finish the at least the first part: a SD card data logger with GPS :-): I calculate global positioning and time information, can use it in Google maps and store it on a SD card:
Adafruit GPS Data Logger Shield on a FRDM-KL25Z Board
The standard Eclipse registers view only shows the core registers:
Standard Registers View in Eclipse
I think it would be great to have a view to see all the device peripheral registers too?
Embedded System Registers View
If you want the same, then this article is for you. It works both for stock Eclipse and Freescale Kinetis Design Studion (KDS) 🙂
11 teams with a total of 14 robots participated at the May 2014 Mini-Sumo robot competition this week at the Lucerne University of Applied Sciences and Arts in Horw/Switzerland.
Sumo, ready to battle
The Freescale FRDM-K64F is a great board for data logger applications: it has a powerful ARM Cortex M4F with 120 MHz, 1 MB Flash and 256 KByte RAM. Best of all: it already has a micro SD card socket on the board :-).
Data Logger with FRDM-K64F
Feeling that building a project in Eclipse (including Kinetis Design Studio) takes a long time? Then probably the ‘parallel build’ option is not enabled in your project: Using parallel build option reduces the needed time by factors. To give an example, to build a project with 56 source files takes 32 seconds without parallel build enabled:
no parallel build
With parallel build enabled this gets reduced down to less than 10 seconds:
Parallel Build Enabled
🙂
For the next semester I will do things differently in my advanced embedded systems programming course (INTRO) at the University of Lucerne: Instead of using the Freescale provided CodeWarrior, we will use a DIY tool chain for ARM with Eclipse Kepler.
Eclipse Kepler Ready for Classroom Usage
That way we we can offer students an open and convenient tool chain for their lab work, course assignments and own projects both at work and at home. So this post is about spending about 30 minutes to build your own tool chain which then can passed to students and coworkers so they have a complete toolchain installed in a few minutes.
In “Watchpoints: Data Breakpoints” I used the Eclipse based CodeWarrior to set breakpoints so the debugger stops when my application is writing or reading a certain memory location. That CodeWarrior is based on an earlier Eclipse version, and things are different in Eclipse Kepler and not so easy to find. So here is how I can use watchpoints in Eclipse Kepler:
Watchpoints in Breakpoint View
With the Joystick shield I have a convenient way to drive and control a Zumo Robot without a wired connection:
Joystick Shield with Robot
While things started promising, there was a power supply problem at the end to be solved…
MCU on Eclipse 