What is polling in UART?
A polled UART is a program that regularly checks the UART receive bit manually to see if a byte is waiting to be received and then does something with it. An interupt driven UART is one that uses the UART’s built in receive interupt that causes an interupt to occur when there’s a byte ready to be received.
Is UART an interrupt?
The UART Interrupt is used to detect the completion of data transmission or reception without continuously polling the flag bit, thus saving processor time. The interrupt is detected with the help of the TXIF and RCIF bits. To use these interrupts, we must first enable GIE and PEIE bits in the INTCON register.
Is interrupt more efficient than polling?
The first advantage is- the performance of microcontroller is far better in Interrupt method than Polling Method. In polling method, the microcontroller is checking continuously whether the device is ready or not, but the chances of data loss are greater in Polling than Interrupt.
What is the difference between an interrupt and a request?
Interrupt is a hardware mechanism in which, the device notices the CPU that it requires its attention. Interrupt can take place at any time. So when CPU gets an interrupt signal trough the indication interrupt-request line, CPU stops the current process and respond to the interrupt by passing the control to interrupt handler which services device.
When to use polled mode or interrupt based method?
Polled mode is also can be used at prototyping, for cores without peripheral needed and for some testing purposes. Interrupts are preferred when low latency is required. If you poll for some condition N times per second, then on average you will discover that condition in time one half of 1/N after it has actually happened.
How does the CPU respond to an interrupt?
The CPU is always checking and waiting for Flag to be raised, like UART raising a flag after a packet is transferred. Forever checking the Flag register. (Best response time) but the CPU cant perform anything else. CPU performs normally, if interrupt happens, CPU will switch context to ISR. if Pin 18 saw a falling edge, perform ISR (1).
When is the best time to use an interrupt?
If the time of the response to an event is has to be consistent (e.g. 1ms +/-10us after after the input line goes high, transmit the event signal) then interrupts are usually best.