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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Therefore you must reserve a RAM register location in each bank of the device at the same offset.
If the program uses the form: Lisez bien les explications en anglais plus bas. Finally, you need to tell PBP that you are using an assembly progrqmmation interrupt handler and where to find it. Un informaticien ne peut compter le nombre d’heures passer devant le clavier. A short interrupt handler is placed at location 4 in the PICmicro.
In this manner, if the save of W “punches through” to another bank, it will not corrupt other data. The interrupt routine should be as short and fast as you can possibly make it. It could be up to 10 seconds later before the interrupt handler is executed.
This should ensure that it is in the first 2K to minimize boundary issues. The PicBasic Pro programs must be compiled using the -ampasm switch to invoke Microchip’s assembler.
You should create variables in the PicBasic Pro program for the express purpose of saving W, the STATUS register and any other register that may need to be altered by the interrupt handler. If the processor context, upon return from the interrupt, is not assemboeur exactly the way you found it, all kinds of subtle bugs and even major system crashes can and will occur.
This instructs the compiler to place the variable at a particular location in RAM. Interrupts in assembly language are a little trickier.
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If you need to alter any of these, assembleeur you probably will, you must save the current values so that you can restore them before allowing the processor to go back ccours what it was doing before it was so rudely interrupted.
The problem occurs in that you have no way of knowing what register bank you are pointing to when the interrupt happens. The appropriate floating point routines Microchip’s AN are included in this zip.
While it is not that difficult, it is not obvious how to make this work properly. If it takes too long to execute, the Watchdog Programmatio could timeout and really make a mess of things. It does not immediately vector to your interrupt handler. Goto loop ‘ Wait here till interrupted. The readme files included in the zip explain the procedures in more detail.
Keep in mind the interrupt flag is checked after programmatio instruction. It immediately jumps to the loop with no interrupt check. As an example, lets say that the PicBasic Pro program just started execution of a Pause when an interrupt occurs.
This is called saving and restoring the processor context.
The best place to put the assembly language interrupt handler is probably at the very beginning of your PicBasic Pro program. The first routine should convert the integer value aint to a floating point value. Cosine starts with a value in binary radians, 0 toas opposed to the usual 0 to degrees. If the PICmicro has 2K or less of assrmbleur space, the registers are not saved.
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To be safe, we need to reserve the same location in each bank. Also, several example programs are included. A special construct has been added to the VAR command to allow this: SIN returns the 8-bit sine of a value. It uses a quarter-wave lookup table to find the result. Turning off this bit tells PBP an interrupt has happened and it will execute the interrupt handler forever.
This will allow PBP to complete each statement more quickly and handle any pending interrupts.
SQR returns the square root of a value. Label is the beginning of your interrupt routine. What this does is send the program back to what it was doing before the interrupt occurred. Generally, floating point operations occur between 2 numbers, so a second integer bint should also be converted. BAS que vous trouver dans C: While it seems a simple matter to save W in any RAM register, it is actually somewhat more complicated.
Sine starts with a value in binary radians, 0 toas opposed to the usual 0 to degrees. The routine should end with an Retfie instruction to return from the interrupt and allow the processor to pick up where it left off in your PicBasic Pro program.
In this case we will choose the first location in each bank. Below is one example program that demonstrates the use of the libraries. The necessary PicBasic Pro source code to integrate either the bit or bit Microchip floating point routines into your program, FP. Finally, the floating point number is converted back into an integer aint so that PicBasic Pro can use it again. If it is buffering characters from a serial port, many characters will be missed. Un programmeur averti en vaut deux.
Interrupts in Assembler Interrupts in assembly language are a little trickier. If you don’t have their assembler, it also may be downloaded from their web site.