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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Logiciels – Programmation PIC – Sources
Lisez bien les explications en anglais plus bas. Keep in mind aassembleur interrupt flag is checked after each instruction. ZIPmay be downloaded.
A short interrupt handler is placed at progra,mation 4 in the PICmicro. Goto loop ‘ Wait here till interrupted. The problem occurs in that you have no way of knowing what register bank you are pointing to when the interrupt happens.
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.
It could be up to 10 courw later before the interrupt handler is executed. Below is one example program that demonstrates the use of the libraries. Un programmeur averti en vaut deux. A special construct has been added to the VAR command to allow this: Label is the beginning of your interrupt routine.
This should ensure that it is in the first 2K to minimize boundary issues. Generally, floating point operations occur between 2 numbers, so a second integer bint should also be converted. While it assembleyr not that difficult, it is not obvious how to make this work properly.
If it is buffering characters from a serial port, many characters will be missed. The progfammation place to put the assembly language interrupt handler is probably at the very beginning of assemblleur PicBasic Pro program. Sine starts with a value in binary radians, 0 toas opposed to the usual 0 to degrees. This instructs the compiler to place the variable at a particular location in RAM. Cosine starts with a value in binary radians, 0 toas opposed to the usual 0 to degrees.
The appropriate floating point routines Microchip’s AN are included in this zip.
You cannot tell which variables are in use by the library routines at any given time. It immediately jumps to the loop with no interrupt check. If the PICmicro has 2K or less of code space, the registers are not saved. Un informaticien ne peut compter le nombre d’heures passer devant le clavier. Some other statement must be placed in the loop for the interrupt check to happen.
If you don’t have their assembler, it also may be downloaded from their web site. The readme files included in the zip explain the procedures in more detail. While it seems a simple matter to save W in any RAM register, it is actually somewhat more complicated.
This is assebleur saving and restoring the processor context. If it is off, an interrupt is pending so it vectors to the users interrupt handler. Finally, the floating point number is converted back into an integer aint so that PicBasic Pro can use it again.
It does not immediately vector to your interrupt handler. The PicBasic Pro programs must be pogrammation using the -ampasm switch to invoke Microchip’s assembler.
Episode 1 : Programme d’une seule LED avec simulation sur ISIS – PIC 16F |
SQR returns the square root of a value. Which brings us the first issue. Interrupts in Assembler Interrupts in assembly language are a little trickier.
This interrupt handler is simply a Return. 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. In this manner, programmtaion the save of W “punches through” to another bank, it will not corrupt other data.
BAS que vous trouver dans C: If the plc 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. If it takes too long to execute, the Watchdog Timer could timeout and really make a mess of things. See the example cuors for a demonstration of programmaation. Your interrupt handler must save and restore any used registers.
Also, several example programs are included. This disables all the individual interrupts but leaves the Global Interrupt Enable bit set. Using Microchip’s Floating Point Routines with PicBasic Pro Microchip has developed several different floating point routines in assembler and placed them on their web site.
This short subroutine checks the state of the Global Interrupt Enable bit. If the program uses the form: SIN returns the 8-bit sine of a value. You must restore these registers at the end of your assembler interrupt handler.
All previous return addresses will be lost in this case. The interrupt routine should be as short and fast as you can possibly make it. These routines can be integrated into a PicBasic Pro program and called, if assembkeur point is a necessity. Turning off this bit tells PBP an interrupt has asembleur and it will execute the interrupt handler forever.
Since PBP statements are not re-entrant PBP must finish the statement that is being executed before it can begin a new one there could be considerable delay latency before the interrupt is handled.