Extraits de la documentation technique Microchip du PIC 16F Savoir concevoir et écrire un programme assembleur. cours sur les interruptions IF3. PiKdev, An IDE for the development of PIC based . http:// Cours de programmation. Lors de l’écriture d’un programme en assembleur 68HC11, une directive d’ assemblage Figure 6: Logiciel PCBUG11 en cours d’utilisation.
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Circuit a microcontrôleurs (MCU)
Finally, the floating point number is converted back into an integer aint so that PicBasic Pro can use it again.
It could be up to 10 seconds later before the interrupt handler is executed. Cosine starts with a value in binary radians, 0 toas opposed to the usual 0 to degrees. Keep in mind proyrammation interrupt flag is checked after each instruction.
Sine starts with a value in binary radians, 0 toas opposed to the usual 0 to degrees. To be safe, we need to reserve the same location in each bank.
If the processor context, upon return from the interrupt, is not left exactly the way you found it, all kinds of subtle bugs and even major system crashes can and will occur.
This disables all the individual interrupts but leaves the Global Interrupt Enable bit set. Interrupts in assembly language are a little trickier. This short subroutine checks the state of the Global Interrupt Enable bit.
In this case we will choose the first location in each bank. The first routine should convert the integer value aint to a floating point value. All previous return addresses will be lost in this case. Finally, you need to tell PBP that you are using an assembly language interrupt handler and where to find it. SIN returns the 8-bit sine of a value. Which brings us the first issue. Some other statement must be placed in the loop for the interrupt check to happen.
This allows sections of code to execute without the possibility of being interrupted. If it takes too long to execute, the Watchdog Timer could timeout and really make a mess of things. The routine should end with an Retfie instruction to dours from the interrupt and allow the processor to pick up where it left off in your PicBasic Pro program.
If you don’t have their assembler, assmbleur also may be downloaded from their web site. This should ensure that it is in the first 2K to minimize boundary issues. This interrupt handler is simply a Return. The problem occurs in that you have no way of knowing what register bank you are pointing to when the interrupt happens.
Lisez bien les explications en anglais plus bas. It uses a quarter-wave lookup table to find the result. See the example below for a demonstration of this.
These routines can be integrated into a PicBasic Pro program and called, if floating point is a necessity. BAS que vous trouver dans C: This instructs the compiler prograjmation place the variable at a particular location in RAM.
Episode 1 : Programme d’une seule LED avec simulation sur ISIS – PIC 16F |
It does not immediately vector to your interrupt handler. ZIPmay be downloaded. The PicBasic Pro programs must be compiled using the -ampasm switch to invoke Microchip’s assembler. While it seems a simple matter to save W in any RAM register, it is actually somewhat more complicated. If you need to alter any of these, and you probably will, you must save the current values so that you can restore them before allowing the processor to go back to what it was doing before it was so rudely interrupted.
Your interrupt handler must save and restore any used registers. A short interrupt handler is placed at location 4 in the PICmicro. If the program uses the form: You must restore these registers at the end of your assembler interrupt handler. If it is off, an interrupt is pending so it vectors to the users interrupt handler.
Episode 1 : Programme d’une seule LED avec simulation sur ISIS – PIC 16F877
As an example, lets say ipc the PicBasic Pro program just started execution of a Pause when an interrupt occurs. Interrupts in Assembler Interrupts in assembly language are a little trickier. While it is not that difficult, it is not obvious how to make this work properly.
As an example, let’s choose the 16C74 A. Un programmeur averti programmarion vaut deux. What this does is send the program back to what it was doing before the interrupt occurred. If you have reserved a location in Bank0 and the current register pointers are set to Bank1, for example, you could overwrite an unintended location.
If it is buffering characters from a serial port, many characters will be missed. The appropriate floating point routines Microchip’s AN are included in this zip.
It immediately jumps to the loop with no interrupt check. Turning off this bit tells PBP an interrupt has happened and it will execute the interrupt handler forever.
Logiciels – Programmation PIC – Sources
A special construct has been added to the VAR command to allow this: In this manner, if the save of W “punches through” to another bank, it will not corrupt other data. Therefore you must reserve a RAM register location in each bank of the device at the same offset.
You cannot tell which variables are in use by the library routines at any given time. The best aszembleur to put the assembly language interrupt handler is probably at the very beginning of your PicBasic Pro program. Below is one example program that demonstrates the use of the libraries.