interrupt-handling | 易学教程

How ARM system mode is useful in nested interrupt?

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问题 Can someone explain me, how exactly system mode works when we have nested interrupt ? As per ARM site ARMv4 and later architectures include a privileged mode called System mode, to overcome this problem. System mode shares the same registers as User mode, it can run tasks that require privileged access, and exceptions no longer overwrite the link register. So how system mode make use of registers of User mode ? And upto what hierarchy level nested interrupts can be handled? 回答1: Trying to

Stop Thread right after one Minute

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问题 I have a JButton to invoke my thread. But what I actually want to do is to stop the thread just after the one minute! My actionListener Method is: private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) { new Frame2().setVisible(true); Thread t=new Thread(new Frame2()); t.start(); } My thread to run for only one minute is as follow: public void run(){ int i; while(!Thread.currentThread().isInterrupted()){ for(i=0;i<=100;i++){ if(i==100){ Thread.currentThread().interrupt(); } try

Faster quadrature decoder loops with Python code

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问题 I'm working with a BeagleBone Black and using Adafruit's IO Python library. Wrote a simple quadrature decoding function and it works perfectly fine when the motor runs at about 1800 RPM. But when the motor runs at higher speeds, the code starts missing some of the interrupts and the encoder counts start to accumulate errors. Do you guys have any suggestions as to how I can make the code more efficient or if there are functions which can cycle the interrupts at a higher frequency. Thanks, Kel

int 13h in windows protected mode?

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问题 Could we use the Int 13h (direct disk read/write) in Windows operating systems or does the windows protected mode not allow us, and if so is there a work round? Thanks in advance. 回答1: No, The Windows sub-system, upon initialization during boot, would have reconfigured the BIOS interrupt handling for the kernel as the BIOS calls are 16bit, not protected mode and hence int 13h would be invalid. That is the reason why there are drivers which are written for 32bit protected mode which bypasses

What happens to software interrupts in the pipeline?

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问题 After reading this: When an interrupt occurs, what happens to instructions in the pipeline? There is not much information on what happens to software interrupts but we do learn the following: Conversely, exceptions, things like page faults, mark the instruction affected. When that instruction is about to commit, at that point all later instructions after the exception are flushed, and instruction fetch is redirected. I was wondering what would happen to software interrupts (INT 0xX) in the

STM32F207 I2C test failing

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问题 I am learning embedded development on the STM3220G-EVAL board with the STM32F207 microcontroller. I have tried to test the I2C interface by interfacing the two I2C2 and I2C3 modules on the same chip and sending/receiving a character. Here is the code I have currently written (using mdk-arm 5): #include <stm32f2xx.h> volatile uint8_t data = 'a', recv = 'x'; void i2c_init(void); void I2C2_EV_IRQHandler(void) { volatile uint16_t stat, dummy; stat = I2C2->SR1; switch(stat) { // SB set; read SR1

Function parameter passing in a Linux kernel interrupt handler (from asm to C)

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问题 When I read the Linux kernel source, I came across this piece of code: __visible void __irq_entry smp_apic_timer_interrupt(struct pt_regs *regs) { struct pt_regs *old_regs = set_irq_regs(regs); entering_ack_irq(); local_apic_timer_interrupt(); exiting_irq(); set_irq_regs(old_regs); } The function smp_apic_timer_interrupt() takes one parameter. The calling of this function is by a piece of assembly language code: ENTRY(apic_timer_interrupt) RING0_INT_FRAME; ASM_CLAC; pushl_cfi $~(0xef); SAVE

Faster quadrature decoder loops with Python code

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I'm working with a BeagleBone Black and using Adafruit's IO Python library. Wrote a simple quadrature decoding function and it works perfectly fine when the motor runs at about 1800 RPM. But when the motor runs at higher speeds, the code starts missing some of the interrupts and the encoder counts start to accumulate errors. Do you guys have any suggestions as to how I can make the code more efficient or if there are functions which can cycle the interrupts at a higher frequency. Thanks, Kel Here's the code: # Define encoder count function def encodercount(term): global counts global Encoder_A

int 13h in windows protected mode?

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Could we use the Int 13h (direct disk read/write) in Windows operating systems or does the windows protected mode not allow us, and if so is there a work round? Thanks in advance. No, The Windows sub-system, upon initialization during boot, would have reconfigured the BIOS interrupt handling for the kernel as the BIOS calls are 16bit, not protected mode and hence int 13h would be invalid. That is the reason why there are drivers which are written for 32bit protected mode which bypasses the BIOS completely. Which begs the question - why are you trying to do that? Windows will kill your code on

Relocate the ARM exception vectors?

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How would I relocate the ARM exception vectors ? Basically, I need to be able to remap them in a way, so when the ARM core tries to execute the vector, it should execute the custom exception vector that is stored in kernel's RAM bit and not in the ROM that is at 0x0 . Is that possible? Or am I meant to route the interrupts to the kernel from the ROM ? So essentially, is there a way of telling the ARM core, " here is the new address for your vector table "? I know that you can start the CPU in the high vector mode, but that's not what I'm looking for. I need to be able to set the vector base to