isr

PLP: Timer and Button Interrupt Service Routine

由 强颜欢笑 提交于 2019-12-13 15:40:55
问题 So I'm having trouble figuring out how to trigger a Timer interrupt (Every 200 cycles) and a button interrupt. When I hit the button interrupt all it seems to do is temporarily pause the counter for a split second and then continue counting. Then it never registers another button interrupt no matter how often I click it on PLP. What the button interrupt is suppose to do is set the register $a1 to 1 (or a non zero number) which is suppose to reset the counter. The Timer interrupt is suppose to

C++ ISR using class method?

由 那年仲夏 提交于 2019-12-12 17:15:54
问题 Is it possible to use a class method as the Interrupt Service Routine? I have an ISR written and working in C using a function: static void interrupt far ISR(...) {} I've tried in C++ to create a method (prototype): void interrupt far ISR(...); Then the implementation: #pragma interrupt void interrupt far MyClass::ISR(...) { ... } But I get all sorts of errors when I try to use this with 'setvect': setvect(muint16Vector, &ISR); I'm trying to write a class to service a serial port, the ISR

Cannot modify data segment register. When tried General Protection Error is thrown

由 我的未来我决定 提交于 2019-12-12 11:43:13
问题 I have been trying to create an ISR handler following this tutorial by James Molloy but I got stuck. Whenever I throw a software interrupt, general purpose registers and the data segment register is pushed onto the stack with the variables automatically pushed by the CPU. Then the data segment is changed to the value of 0x10 (Kernel Data Segment Descriptor) so the privilege levels are changed. Then after the handler returns those values are pop ed. But whenever the value in ds is changed a

Is it possible to set ISR Handler at runtime on M0+

由 醉酒当歌 提交于 2019-12-11 04:37:48
问题 I have a "default" resetVectors.c file for my SAMD21 ARM M0+. It has something that looks like: __attribute__ ((section(".vectors"))) const DeviceVectors exception_table = { ... }; in it that defines where different handler stubs. For testing purposes, I want to use one of the unused peripheral IRQs. By default, the unused ones are set to NULL addresses. I have demonstrated to myself that I can modify that file and at compile time change my unused IRQ (21) to fire a handler. BUT, is it

How is ISR a callback function

由 蹲街弑〆低调 提交于 2019-12-11 03:49:00
问题 The wikipedia entry states: In computer system programming, an interrupt handler, also known as an interrupt service routine or ISR, is a callback function in microcontroller firmware, an operating system or a device driver, whose execution is triggered by the reception of an interrupt. How is ISR a callback. Is it the PC value stored on stack itself is the callback function? I.e., the ISR calls the interrupted function back. Hence the interrupted function is a callback. 回答1: A bit of setup

What is the correct way of using C++ objects (and volatile) inside interrupt routines?

由 给你一囗甜甜゛ 提交于 2019-12-10 15:59:14
问题 I am currently working with Atmel AVR microcontrollers (gcc), but would like the answer to apply to the microcontroller world in general, i.e. usually single-threaded but with interrupts. I know how to use volatile in C code when accessing a variable that can be modified in an ISR. For example: uint8_t g_pushIndex = 0; volatile uint8_t g_popIndex = 0; uint8_t g_values[QUEUE_SIZE]; void waitForEmptyQueue() { bool isQueueEmpty = false; while (!isQueueEmpty) { // Disable interrupts to ensure

Statically Defined IDT

由 我是研究僧i 提交于 2019-12-10 03:52:14
问题 I'm working on a project that has tight boot time requirements. The targeted architecture is an IA-32 based processor running in 32 bit protected mode. One of the areas identified that can be improved is that the current system dynamically initializes the processor's IDT (interrupt descriptor table). Since we don't have any plug-and-play devices and the system is relatively static, I want to be able to use a statically built IDT. However, this proving to be troublesome for the IA-32 arch

Statically Defined IDT

由 点点圈 提交于 2019-12-05 04:41:24
I'm working on a project that has tight boot time requirements. The targeted architecture is an IA-32 based processor running in 32 bit protected mode. One of the areas identified that can be improved is that the current system dynamically initializes the processor's IDT (interrupt descriptor table). Since we don't have any plug-and-play devices and the system is relatively static, I want to be able to use a statically built IDT. However, this proving to be troublesome for the IA-32 arch since the 8 byte interrupt gate descriptors splits the ISR address. The low 16 bits of the ISR appear in

How to measure ISR execution time?

由 人走茶凉 提交于 2019-12-04 21:51:52
I am on linux kernel 2.6.32. I am facing an issue in which one of the two ISR (serial and ethernet) are taking more time (hundreds of microseconds) on several occasion/under some scenarios which I don't know. I would like to get the time difference every time the ISR executes. What would be the best way (least expensive in terms of overhead involved). I don't see ARM architecture has some TSC register (read_tsc api) which would give me direct access to time as it offers on some other architecture. So Idea is 1) The moment ISR is invoked measure time 2) the moment ISR is complete measure the

What happens when you disable interrupts, and what do you do with interrupts you don't know how to handle?

由 …衆ロ難τιáo~ 提交于 2019-12-04 11:39:58
问题 When you disable interrupts (with the cli instruction in x86), what exactly happens? Does the PIC wait for you to turn on interrupts, and fire the interrupt when that happens? (If so, how long does it wait, and what happens if the time 'expires'?) Does the interrupt -- from the device's perspective -- get sent into a "black hole", with no response? Does the PIC somehow tell the device that "the CPU is busy" or something? Or does something else happen? Also, how do you deal with an interrupt
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