Difference between revisions of "Embedded System Tutorial File I/O"
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Please follow the steps precisely in order to complete the objectives of the assignment. If you use the C++ FreeRTOS framework, it should make the assignment significantly easy. | Please follow the steps precisely in order to complete the objectives of the assignment. If you use the C++ FreeRTOS framework, it should make the assignment significantly easy. | ||
| − | # Create a '''<code>producer task</code>''' that takes 1 light sensor value every 1ms | + | # Create a '''<code>producer task</code>''' that takes 1 light sensor value every 1ms. |
| + | #: Collect the average of the 100 readings. | ||
| + | #: Write average value of 100ms (100 samples) to the '''<code>sensor queue</code>'''. | ||
#: Use medium priority for this task | #: Use medium priority for this task | ||
# Create a '''<code>consumer task</code>''' that pulls the data off the '''<code>sensor queue</code>''' | # Create a '''<code>consumer task</code>''' that pulls the data off the '''<code>sensor queue</code>''' | ||
Revision as of 00:57, 10 May 2014
In this project, we will attempt to "combine" all the FreeRTOS knowledge into a single assignment.
Assignment
Please follow the steps precisely in order to complete the objectives of the assignment. If you use the C++ FreeRTOS framework, it should make the assignment significantly easy.
- Create a
producer taskthat takes 1 light sensor value every 1ms.- Collect the average of the 100 readings.
- Write average value of 100ms (100 samples) to the
sensor queue. - Use medium priority for this task
- Create a
consumer taskthat pulls the data off thesensor queue- Use infinite timeout value during queue receive API
- Open a file (sensor.txt), and append the data to an output file on the SD card.
- Save the data in this format:
printf("%i, %i\n", time, light)" - Just leave the file in "open" mode, such that it will flush the data after enough data is written rather than flushing it upon each write, which will consume a lot of CPU.
- Use medium priority for this task
- Create a
watchdog taskthat monitors the operation of the two tasks.- Use high priority for this task.
- Every sixty seconds, save the CPU usage info to a file named "cpu.txt". See terminal command "infoHandler" for reference. Open the file, write the file, and close it immediately so the data is immediately flushed.
- Towards the end of the other tasks, set a bit using the
xEventGroupSetBits() - Task 1 should set bit1, Task 2 should set bit2 etc.
- Use a timeout of 1 second, and wait for all the bits to set. If there are two tasks, wait for bit1, and bit2 etc.
- If you fail to detect the bits are set, that means that the other tasks did not reach the end of the loop.
- In the event of failed to detect the bits, append a file (stuck.txt) with the information about which task may be "stuck"
- Open the file, append the data, and close the (stuck.txt) file to flush out the data immediately.
- Create a terminal command to "suspend" and "resume" a task by name.
- "task suspend task1" should suspend a task named "task1"
- "task resume task2" should suspend a task named "task2"
- Run the system, and under normal operation, you will see a file being saved with sensor data values.
- Plot the file data in Excel to demonstrate.
- Suspend the producer task. The watchdog task should display a message and save relevant info to the SD card.
- Let the system run for a while, and note down the CPU usage in your text file.
- Change the ADC sensor implementation
- Modify the source code of how the light sensor class obtains the ADC value by not using ADC polling mode.
- Instead of "trigger ADC", "wait for completion", and "read value", modify it to this:
- Upon ADC initialization, enable ADC interrupt, which should "give" a semaphore.
- After triggering the ADC, wait for ADC semaphore to be given, and then read the value.
- After changing the ADC behavior, let the system run for a while, and note down the CPU usage again.
What you created is a "software watchdog". This means that in an event when a loop is stuck, or a task is frozen, you can save relevant information such that you can debug at a later time.
After completing the assignment, you will get a sensor of how the CPU is utilized, and how to use a new FreeRTOS event group API. All together, you should acheive a better sensor of designing your tasks and using the File I/O for debugging purposes.
