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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It uses a quarter-wave lookup table to find the result. If it takes too long to execute, the Watchdog Timer could timeout and really make a mess of things. 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.
Finally, programmayion floating point number is converted back into an programamtion aint so that PicBasic Pro programmationn use it again. Interrupts in assembly language are a little trickier. Finally, you need to tell PBP that you are using an assembly language interrupt handler and where to find it.
It could be up to 10 seconds later before the interrupt handler is executed. The necessary PicBasic Pro source code to integrate either the bit or bit Microchip floating point routines into your program, FP.
Below is one example program that demonstrates the use of the libraries. The problem occurs in that you have no way of knowing what register bank you are pointing to when the interrupt happens.
Label is the beginning of your interrupt routine. All previous return addresses will be lost in this case. Interrupts in Assembler Interrupts in assembly language are a little trickier. The first routine should convert the integer value aint to a floating point value.
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.
Episode 1 : Programme d’une seule LED avec simulation sur ISIS – PIC 16F877
To be safe, we need to reserve the same location in each bank. This interrupt handler is simply a Return. Your interrupt handler must save and restore any used registers. 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. Turning off this bit tells PBP an interrupt has happened and it will execute the interrupt handler forever.
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. Keep in mind the interrupt flag is checked after each instruction. The PicBasic Pro programs must be compiled using the -ampasm switch to invoke Microchip’s assembler.
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This short subroutine checks the state of the Global Interrupt Enable bit. If it is off, an interrupt is pending so it vectors to the users interrupt handler.
While it seems a simple matter courx save Awsembleur in any RAM register, it is actually somewhat more complicated. BAS que vous trouver dans C: If the processor context, upon return from the interrupt, is not left exactly the way you found it, all ccours of subtle bugs and even major system crashes can and will occur.
A short interrupt handler is placed at location 4 in the PICmicro. ZIPmay be downloaded. Sine starts with a value in binary radians, 0 toas opposed to the usual 0 to degrees.
Generally, floating point operations occur between 2 numbers, so a second integer bint should also be converted. Which brings us the first issue. SQR returns the square root of a value. 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.
Circuit a microcontrôleurs (MCU)
While it is not that difficult, it is not obvious how to make this work properly. You must restore these registers at the end of your assembler interrupt handler.
It does not programmatin vector to your interrupt handler.
This will allow PBP couts complete each statement more quickly and handle any pending interrupts. Some other statement must be placed in the loop for the interrupt check to happen. The readme files included in the zip explain the procedures in more detail.
As an example, lets say that the PicBasic Pro program just started execution of a Pause when an interrupt occurs. You cannot tell which variables are in use by the library routines at any given time. Also, several example programs are included.
This allows sections of code to execute without the possibility of being interrupted. This is called saving and restoring the processor context. SIN returns the 8-bit sine of a value. This disables all the individual interrupts but leaves the Global Interrupt Enable bit set. This instructs the compiler to place the variable at a particular location in RAM.
Lisez bien les explications en anglais plus bas. These routines can be integrated into a PicBasic Pro program and called, if floating point is a necessity.
This should ensure that it is in the first 2K to minimize boundary issues. 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.