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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While it assfmbleur a simple matter program,ation save W in any RAM register, it is actually somewhat more complicated. As an example, lets say that the PicBasic Pro program just started execution of a Pause when an interrupt occurs. Since PBP statements are not re-entrant PBP must finish the statement that is being executed before it can programmaiton a new one there could be considerable delay latency before the interrupt is handled.
You cannot tell which variables are in use by the library routines at any given time. SQR returns the square root of a value. This short subroutine checks the state of the Global Interrupt Enable bit. In this case we will choose the first location in each bank. If you don’t have their assembler, it also may be downloaded from their pdogrammation site. What this does is send the program back to what it was doing before the interrupt occurred.
The problem occurs in that you have no way of knowing what register bank you are pointing to when the interrupt happens. Finally, the floating point number is converted back into an integer aint so that PicBasic Pro can use it again.
It uses a quarter-wave lookup table to find the result. This will allow PBP to complete each statement more quickly and handle any pending interrupts.
Below is one example program that demonstrates the programmatio of the libraries.
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.
Cosine starts with a value in binary radians, 0 toas opposed to the usual 0 to degrees. This disables all the individual interrupts but leaves the Global Interrupt Enable bit set.
It does not immediately vector to your interrupt handler.
Circuit a microcontrôleurs (MCU)
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. If it is off, an interrupt is pending so it vectors to the users interrupt handler. Keep in mind the interrupt flag is checked after each instruction.
All previous return addresses will be lost in this case. 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.
If the PICmicro has 2K or less of code space, the registers are not saved.
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This instructs the compiler to place the variable at a particular location in RAM. Finally, you need to tell PBP that you are using an assembly language interrupt handler and where to find it.
Label is the beginning of your interrupt routine. The interrupt routine should be as cpurs and fast as prkgrammation can possibly make it. In this manner, if the save of W lrogrammation through” to another bank, it will not corrupt other data. Since PicBasic Pro only works with integers, the result will always be an 8-bit integer no larger than the actual result.
This is called saving and restoring the processor context. Some other statement must be placed in the loop for the interrupt check to happen. These routines can be integrated into a PicBasic Pro program and called, if floating point is a necessity.
To be safe, proggammation need to reserve the same location in each bank. The PicBasic Pro programs must be compiled using the -ampasm switch to invoke Microchip’s assembler.
If it takes too long to execute, the Watchdog Timer could timeout and really make a mess of things. Lisez bien les explications en anglais plus bas. Interrupts in Assembler Interrupts in assembly language are a little trickier. Generally, floating point operations occur between 2 numbers, so a second integer bint should also be converted.
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.
Turning off this bit tells PBP an interrupt has happened and it will execute the interrupt handler forever.
Episode 1 : Programme d’une seule LED avec simulation sur ISIS – PIC 16F877
Goto loop ‘ Wait here till interrupted. 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.
It could be up to 10 seconds later before the interrupt handler is executed.