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Trace: • IoT Networks: Laboratory 3 - CoAP • Bluetooth Low Energy for STM32 - peripheral write • ESP32 BLE in Arduino. Part2: Setting-up BLE Server • ESP32 BLE in Arduino. Part1: Setting-up BLE Beacon • Laboratory on the Internet of Things - Advanced IoT Hardware - on-site edition • ESP32 BLE in Arduino. Part 4: BLE Client • Zephyr BLE peripheral • nRF52840 Zephyr BLE client • Zephyr Beacon example • Laboratory on GPIO use in Zephyr OS
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en:edu:zmitac:s2:aih:lab:nrf52zephyrtimers

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en:edu:zmitac:s2:aih:lab:nrf52zephyrtimers [2023/12/06 22:48] – [Summary of the tasks for the laboratory] ktokarzen:edu:zmitac:s2:aih:lab:nrf52zephyrtimers [2023/12/06 23:05] (current) – [Timer use] ktokarz
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-====== Zephyr timers ======+====== Zephyr timers and work queues ======
 A timer in Zephyr OS is a kernel object that measures the time using the internal system clock. When a timer reaches a specified time limit it can carry an action as specified in the application. In an operating system, the timer entity is software-based opposite to the hardware timer unit implemented in the microcontroller. Software timers use hardware timers to operate, and in general, the operating system keeps time-dependent actions. Zephyr OS allows one to define the number of timers which can be used to measure periods, asynchronously start some actions, control LED blinking, etc. A timer in Zephyr OS is a kernel object that measures the time using the internal system clock. When a timer reaches a specified time limit it can carry an action as specified in the application. In an operating system, the timer entity is software-based opposite to the hardware timer unit implemented in the microcontroller. Software timers use hardware timers to operate, and in general, the operating system keeps time-dependent actions. Zephyr OS allows one to define the number of timers which can be used to measure periods, asynchronously start some actions, control LED blinking, etc.
-When the timer is fired the system work queue task is started. The system work queue is optional and it's defined by a kernel if any application makes use of it. It is available to any application or kernel code that requires work queue support. We will present the work queues in the next exercise.+When the timer is fired the system work queue task is started. The system work queue is optional and it's defined by a kernel if any application makes use of it. It is available to any application or kernel code that requires work queue support. We will present the work queues at the end of this exercise.
  
 As with other tasks, the timer task should be as short as possible and non-blocking. As with other tasks, the timer task should be as short as possible and non-blocking.
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 The timer object must be defined and initialized. Its function is automatically added to the system work queue as the task, so we don't need to do anything with the queue. Let's try to modify the blinky code from the first laboratory on GPIOs to add a second LED blinking as the result of timer expiration. First, we need to add the timer object declaration. The timer object must be defined and initialized. Its function is automatically added to the system work queue as the task, so we don't need to do anything with the queue. Let's try to modify the blinky code from the first laboratory on GPIOs to add a second LED blinking as the result of timer expiration. First, we need to add the timer object declaration.
 <code> <code>
-        struct k_timer led_timer;+struct k_timer led_timer;
 </code> </code>
 Next, we add the expiry function which will toggle the state of LED every call. Next, we add the expiry function which will toggle the state of LED every call.
 <code> <code>
 void led_timer_function(struct k_timer *timer_id) void led_timer_function(struct k_timer *timer_id)
- { +{ 
- gpio_pin_set(led_dev, LED1_PIN, (int)led1_is_on); +   gpio_pin_set(led_dev, LED1_PIN, (int)led1_is_on); 
- led1_is_on = !led1_is_on; +   led1_is_on = !led1_is_on; 
- }+}
 </code> </code>
 In the main, we have to add two functions: one to initialize the timer, and a second for starting it. In the main, we have to add two functions: one to initialize the timer, and a second for starting it.
 <code> <code>
- k_timer_init(&led_timer, led_timer_function, NULL); +k_timer_init(&led_timer, led_timer_function, NULL); 
- k_timer_start(&led_timer, K_MSEC(200), K_MSEC(300));+k_timer_start(&led_timer, K_MSEC(200), K_MSEC(300));
 </code> </code>
 Of course, there is a need to add and configure a second LED. This can be done as LED0 in the blinky example so we are not going to repeat the detailed description here. Of course, there is a need to add and configure a second LED. This can be done as LED0 in the blinky example so we are not going to repeat the detailed description here.
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 #if DT_NODE_HAS_STATUS(LED0_NODE, okay) #if DT_NODE_HAS_STATUS(LED0_NODE, okay)
 #define LED0 DT_GPIO_LABEL(LED0_NODE, gpios) #define LED0 DT_GPIO_LABEL(LED0_NODE, gpios)
-#define PIN     DT_GPIO_PIN(LED0_NODE, gpios)+#define PIN DT_GPIO_PIN(LED0_NODE, gpios)
 #define FLAGS DT_GPIO_FLAGS(LED0_NODE, gpios) #define FLAGS DT_GPIO_FLAGS(LED0_NODE, gpios)
 #else #else
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 then the function for the work item must be defined: then the function for the work item must be defined:
 <code> <code>
-void my_work_item_function(struct k_work *my_work_item){ +void my_work_item_function(struct k_work *my_work_item) 
- printk("Work item executed\n");+{ 
 +   printk("Work item executed\n");
 } }
 </code> </code>
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 2. Add to the timer expiry function the line that is executed longer than the timer period. This can be the line as follows: 2. Add to the timer expiry function the line that is executed longer than the timer period. This can be the line as follows:
 <code> <code>
-for (int i=0; i<40; i++) printk("counter = %d \n", i);+for (int i=0; i<40; i++)  
 +{ 
 +   printk("counter = %d \n", i); 
 +}
 </code> </code>
 3. Observe the results while adjusting the max iteration value, and explain observations in the report.\\ 3. Observe the results while adjusting the max iteration value, and explain observations in the report.\\
-4. Add at the end of led_timer_function the line shown below and observe the behaviour of the program. <code> k_msleep(1); </code> +4. Add at the end of led_timer_function the line shown below and observe the behaviour of the program.  
-5. Define two work items with their functions. One for the code from the timer function, and the second for the code from the main function. +<code>k_msleep(1);</code> 
 +5. Define two work items with their functions. One for the code from the timer function, and the second for the code from the main function. Instead of executing the full code in the timer and main function submit corresponding work items. The code for the timer work item can look as follows (the code for the main function as well as the work items definition and initialization write on your own). Experiment with the maximal iteration value in the "for" loop. Describe observation results in the report. 
 +<code> 
 +void led_timer_function(struct k_timer *timer_id) 
 +{ 
 +   gpio_pin_set(led_dev, PIN1, (int)led1_is_on); 
 +   led1_is_on = !led1_is_on; 
 +   k_work_submit(&timer_work_item); 
 +} 
 + 
 +void timer_work_item_function (struct k_work *timer_work_item) 
 +{ 
 +   for (int i=0; i<40; i++)  
 +   { 
 +       printk("counter = %d \n", I); 
 +       k_msleep(1); 
 +   } 
 +} 
 +</code>
  
  
en/edu/zmitac/s2/aih/lab/nrf52zephyrtimers.1701899315.txt.gz · Last modified: by ktokarz