Zephyr Thread Assignment

References used - Basic thread example & Hello World

The src/main.c contains two threads wherein the first thread thread1 prints "thread 1" and the time period between prints increments with steps of 1s and overflows back to 1s after 10s. The second thread thread2 prints "thread 2" one second after print by getting a message from thread1.

Assumptions

The repo is cloned in the zephyrproject/zephyr/samples folder in Ubuntu 22.04 LTS. The python environment is activated before building.

Pseudocode

// Define thread stack size, priorities and message queue
//set initial interval
min_delay = 1 second

// Thread 1 function
function thread1():
    interval=min_delay
    msg=false
    sleep for 1s to start the thread after 1s
    while True:
        print "thread 1"
        set msg=true and send message to thread2
        //to increment count and reset interval if overflow
        if interval >= 10 seconds:
            interval=1 second
        else:
            interval+=1 sec
        sleep(interval) //delay for next execution
        

// Thread 2 function
function thread2():
    while True:
        get message from thread 1
        if(received message==true):
            sleep for 1s
            print "thread 2"

// Create and spawn thread 1 
// Create and spawn thread 2

Output

The native posix port of Zephyr is used to run the code present in ./build/zephyr/zephyr.exe

API references from Zephyr Documentation

k_msleep(int32_t ms) -> used to put the current thread to sleep. This routine puts the current thread to sleep for duration milliseconds.

msqg -> Message Queue Structure

void k_msgq_init(struct k_msgq *msgq, char *buffer, size_t msg_size, uint32_t max_msgs)-> used to initialize a message queue.

int k_msgq_get(struct k_msgq *msgq, void *data, k_timeout_t timeout) -> used to receive the message from thread1_entry to thread2_entry

K_THREAD_DEFINE(name, stack_size, entry, p1, p2, p3, prio, options, delay) -> used to define and initialize the threads where the stack_size is 1024 for both the threads and the prio for thread1 and thread2 is set to 5 & 6 respectively.

Steps to recreate

1. Clone the repo in the zephyrproject directory.
2. Activate the python environment source ~/zephyrproject/.venv/bin/activate
3. Delete the build folder to create a fresh build using sudo rm -r build/
4. Move to the folder and build for the native posix port - west build -b native_posix
5. To run the build - ./build/zephyr/zephyr.exe