Understanding Non-Blocking Delay
In firmware development, using a non-blocking delay allows the CPU to execute other tasks while waiting, thereby improving the efficiency of your program. This is particularly useful in embedded systems, where resources can be limited, and tasks often run concurrently. Instead of blocking the CPU with a busy loop, you can achieve non-blocking behavior using timer-based interrupts or scheduling with a state machine.
Using Timer Interrupts
To implement a non-blocking delay using timer interrupts, you'll need to utilize hardware timers provided by most microcontroller platforms. This often involves setting up a timer to trigger an interrupt at a specific interval.
Here's a basic outline of steps to achieve this:
Example code in C might look like the following:
#include <stdint.h>
#include <stdbool.h>
volatile uint32_t timerCounter = 0;
volatile bool delayCompleted = false;
void Timer_Init(void) {
// Configuration code for your specific microcontroller timer
// Set the timer frequency and enable the interrupt
}
void Timer_IRQ_Handler(void) {
// This function is called when the timer interrupt occurs
timerCounter++;
if (timerCounter >= DESIRED_DELAY) {
delayCompleted = true;
timerCounter = 0;
}
}
void NonBlocking_Delay(void) {
if (delayCompleted) {
// Execute code after delay
delayCompleted = false;
}
}
int main(void) {
Timer_Init();
while (1) {
NonBlocking_Delay();
// Other tasks
}
}
This code snippet outlines the basic structure for implementing a non-blocking delay with a timer interrupt, though details will vary based on the specific microcontroller architecture and toolchain used.
Leveraging a State Machine
Another viable approach is to use a state machine pattern, which allows you to check the passage of time at intervals and proceed based on state conditions. This is particularly useful for more complex systems with multiple states or activities.
Define States:
- Establish different states in your firmware where different activities occur based on elapsed time.
Use the System Tick:
- Utilize a system tick timer, often available in real-time operating systems (RTOS) or as part of a microcontroller's peripheral features.
Example code utilizing a simple state machine might look like:
#include <stdint.h>
#include <stdbool.h>
typedef enum {
STATE_IDLE,
STATE_DELAY,
STATE_ACTION
} SystemState;
SystemState currentState = STATE_IDLE;
uint32_t startTime = 0;
uint32_t Get_System_Tick(void) {
// Function to return system tick or milliseconds since startup
}
void Update_State(void) {
switch (currentState) {
case STATE_IDLE:
// Initialization
startTime = Get_System_Tick();
currentState = STATE_DELAY;
break;
case STATE_DELAY:
if (Get_System_Tick() - startTime >= DESIRED_DELAY) {
currentState = STATE_ACTION;
}
break;
case STATE_ACTION:
// Action to be taken after delay
currentState = STATE_IDLE; // Reset to idle or next state
break;
}
}
int main(void) {
while (1) {
Update_State();
// Handle other tasks here
}
}
This example demonstrates how a state machine can control transitions and timing without blocking the CPU. Again, function implementations would need to be tailored to the specific hardware platform.
For both approaches, the non-blocking delay frees up the processor to handle other tasks during the waiting period, making this approach ideal for real-time systems where responsiveness is key. Understanding different methods of implementing non-blocking delay will overall enhance your efficiency as a firmware developer by ensuring that system resources are optimally utilized.
