2. Explain which of the interrupttypes_edge-triggered, level-sensitive, or messa

Question

2. Explain which of the interrupttypes_edge-triggered, level-sensitive, or message switched interrupts-is best suited to the following applications An on-chip temperature sensor is connected to an interrupt pin of the microcontroller. The sensorasserts its interrupt output high when the temperature of the microcontroller chip goes above a set threshold and keeps it high as long as the temperature remains above the threshold. The software in the microcontrolleris designed to shut down certain hardware blockswhen the temperature rises above the threshold and turn them back on aftera set delay. The delay is large enough to guarantee thatthe chip cools down below the settemperature threshold by the time the hardware blocks are re-activated An interrupt pin of the microcontroller is shared by multiple devices with the same priority An interrupt pin ofthe microcontroller is shared by multiple deviceswith differentinterrupt priorities. The microcontroller may occasionally want to postpone the processing of interrupts from low-priority devices, butis always required to process interrupts from high-priority devices quickly Data received from a network interface of the microcontroller is temporarily storedin a FIFbuffer. The FIFO buffer has an interruptoutput that remains high when the FIFOis non-empty and low when the FIFO is empty. The software responds to the interrupt by reading a single byte from the FIFO in the ISR The microcontrolleris connected to a peripheral device over USB. The USB cable only has wires to transfer data. The device needs to interrupt the microcontrollertosignal certain events a. b. c. d. e.

Explanation / Answer

a. For the mentioned point 'Message switched interrupts' will be the best.
- A message-signalled interrupt does not use a physical interrupt line. Instead, a device signals its request for service by sending a short message over some communications medium, typically a computer bus. The message might be of a type reserved for interrupts, or it might be of some pre-existing type such as a memory write.

Same holds for on-chip temperature sensor as well. Since the sensor asserts its interrupt on high and temperature goes above a set threshold. But the software is designed as such that it will shut down certain blocks. So every time a message need to be transmitted.

b. For the mentioned point 'edge triggered interrupts' will be the best.
- An edge-triggered interrupt is an interrupt signalled by a level transition on the interrupt line, either a falling edge (high to low) or a rising edge (low to high). A device, wishing to signal an interrupt, drives a pulse onto the line and then releases the line to its inactive state. If the pulse is too short to be detected by polled I/O then special hardware may be required to detect the edge.

Same holds here as the interrupt pin is shared by multiple devices so as they will cross the edges there will be interrupts.

c.For the mentioned point 'level sensitive interrupts' will be the best.
- A level-triggered interrupt is an interrupt signaled by maintaining the interrupt line at a high or low logic level. A device wishing to signal a Level-triggered interrupt drives the interrupt request line to its active level (high or low), and then holds it at that level until it is serviced.Multiple devices may share a level-triggered interrupt line if they are designed to. The interrupt line must have a pull-down or pull-up resistor so that when not actively driven it settles to its inactive state.Upon deferring a low-priority device is not an option, because this would prevent detection of service requests from higher-priority devices.

Same holds for this as here the micro controller ocassionally wants to postpone based on devices priorities.

d. For the mentioned point 'Message switched interrupts' will be the best.
- A message-signalled interrupt does not use a physical interrupt line. Instead, a device signals its request for service by sending a short message over some communications medium, typically a computer bus. The message might be of a type reserved for interrupts, or it might be of some pre-existing type such as a memory write.

Same holds here as there is a buffer here that deals with the interrupts and the software deals with the response to the interrupts by reading the bytes.

e. For the mentioned point 'Message switched interrupts' will be the best.
- A message-signalled interrupt does not use a physical interrupt line. Instead, a device signals its request for service by sending a short message over some communications medium, typically a computer bus. The message might be of a type reserved for interrupts, or it might be of some pre-existing type such as a memory write.

Same holds here as microcontroller is connected with USB taht has wires to transfer data. Since we know that message-signalled interrupts behave very much like edge-triggered interrupts, in that the interrupt is a momentary signal rather than a continuous condition. Interrupt-handling software treats the two in much the same manner. It will be same for this as well.

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