Yes all “normal” ISAs including 8080 and x86 guarantee that instructions are atomic with respect to interrupts on the same core. Either an instruction has fully executed and all its architectural effects are visible (in the interrupt handler), or none of them are. Any deviations from this rule are generally carefully documented. For example, Intel’s … Read more
You will have to add an eventHandler to the DataReceived event. Below is an example from msdn.microsoft.com, with some edits: see comments!: public static void Main() { SerialPort mySerialPort = new SerialPort(“COM1”); mySerialPort.BaudRate = 9600; mySerialPort.Parity = Parity.None; mySerialPort.StopBits = StopBits.One; mySerialPort.DataBits = 8; mySerialPort.Handshake = Handshake.None; mySerialPort.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler); mySerialPort.Open(); Console.WriteLine(“Press any key … Read more
How do you tell the thread scheduler in linux to not interrupt your thread for any reason? Can’t really be done, you need a real time system for that. The closes thing you’ll get with linux is to set the scheduling policy to a realtime scheduler, e.g. SCHED_FIFO, and also set the PTHREAD_EXPLICIT_SCHED attribute. See … Read more
A trap is an exception in a user process. It’s caused by division by zero or invalid memory access. It’s also the usual way to invoke a kernel routine (a system call) because those run with a higher priority than user code. Handling is synchronous (so the user code is suspended and continues afterwards). In … Read more
Multiple ways to enable/disable interrupts in STM32 mcus: 1. Via ARM-core CMSIS: 1.A. For global interrupts __enable_irq() // enable all interrupts __disable_irq() // disable all interrupts // Returns the current state of the priority mask bit from the Priority Mask // Register. [0 if global interrupts are **enabled** and non-zero if they // are **disabled**] … Read more
I’m a little unclear on differences between DMA and interrupt I/O Differences between DMA and interrupts are bogus because they are not opposing concepts. DMA and interrupts are orthogonal concepts, and both concepts are typically used together. The alternative to DMA is programmed I/O, aka PIO. The alternative to interrupts is polling. Interrupt-driven You need … Read more
How to do high-resolution, timestamp-based, non-blocking, single-threaded cooperative multi-tasking This isn’t a “how to read a sensor” problem, this is a “how to do non-blocking cooperative multi-tasking” problem. Assuming you are running bare-metal (no operating system, such as FreeRTOS), you have two good options. First, the datasheet shows you need to wait up to 9.04 … Read more
Even though the Worker works on an other thread than the one of your main page, and can thus run continuously without blocking the UI, it still runs on a single thread. This means that until your sort algorithm has finished, the Worker will delay the execution of the message event handler; it is as … Read more
Part of the problem has been that I do not know every method call out there that clears the interrupt flag. It is important to clarify that the following methods clear the interrupt flag by just calling them: Thread.interrupted() Thread.isInterrupted(true) — added to your list For this reason Thread.currentThread().isInterrupted() should always be used instead. The … Read more
tl;dr – We switch modes to supervisor and use that stack. You are missing the key point of where control is handed to the CPU via the vector table and the mode is switched. See: entry-armv.S and __vectors_start. The vector stubs is the code where control is initially sent after the branch in the main … Read more