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SYS/BIOS Training Lab: Mailbox App

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This lab is designed to introduce users to some of the concepts of using the SYS/BIOS RTOS.


The project set available for download from this page is called Mailbox. This includes an incomplete project for users to add code per the lab's instructions, and a completed solution project in which all of the code has already been added. To get the most out of using this material, we suggest you start with the incomplete project and attempt to walk through the exercise yourself, using the completed solution project to check your work at the end.

These labs are designed to work on the MSP430 using:

  • MSP430F5438A device
  • MSP-EXP430F5438 Experimenter Board
  • Code Composer Studio v4.x
  • MSP-FET430UIF emulator

Mailbox Lab


  1. Investigate Task and Task communication concepts
  2. Enable some SYS/BIOS instrumentation


  1. Inspect, build, and run the mailbox project; verify the expected output.
  2. Add a call to “Task_setPri(reader0, 2);” in main(), before BIOS_start().
  3. Rebuild, load, and set breakpoints at symbols “readerActive” and “writerActive’; run between breakpoints, use ROV to inspect Task and Mailbox objects.
  4. With a text editor, open the file mailbox_configuration.cfg, change the ‘Instrumentation’ flag to true, rebuild and run.
  5. In ROV, browse to xdc.runtime.LoggerBuf, click the ‘Records’ tab, and then the numeric value; inspect the Task switch Log records.


  1. Can you explain the change the behavior when the reader task priority was increased?
  2. When stopped at “writerActive”, what is the reader task blocked on?
  3. There is one timer object. What is it used for?
  4. What was the peak stack usage by the reader task?
  5. In the Log records, what do the numeric values for LM_switch represent?


Mailbox Lab

Mailbox Lab Solution