Post by thread:PIC16C84 simulator available (C++ source)

Two students of mine have written a 16C84 simulator, in C++. It simulates correctly all peripherals (timer, interrupts, io ports, EEPROM writes), and CPU instructions (including the delay slots after every modification to the PC -- something that the Microchip simulator does not do). The program has a command line interface, and a chunky-graphics output which displays the state (or changes) of I/O pins. A small manual (only in Italian at the moment, sorry) is available with the sources. A short help function (in english, this time) is also included in the command set. The code has been written with Turbo C++, and ported to g++ . It should compile without much problems. The full sources are available at the following address: http://www.iet.unipi.it/~luigi/simulpic.tgz email about this program can be directed to spam_OUTsimulpicTakeThisOuTiet.unipi.it Bug reports, suggestions, enhancements are welcome. Luigi ==================================================================== Luigi Rizzo Dip. di Ingegneria dell'Informazione email: .....luigiKILLspam@spam@iet.unipi.it Universita' di Pisa tel: +39-50-568533 via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 http://www.iet.unipi.it/~luigi/ ====================================================================

Luigi Rizzo <luigiKILLspamLABINFO.IET.UNIPI.IT> writes: > Two students of mine have written a 16C84 simulator, in C++. It > simulates correctly all peripherals (timer, interrupts, io ports, > EEPROM writes), and CPU instructions (including the delay slots > after every modification to the PC -- something that the Microchip > simulator does not do). Do you mean that the Microchip simulator only counts one cycle for instructions that write to PCL? Are they really that inept? Of course, the Microchip documentation erroneously states If an instruction causes the program counter to change (e.g. GOTO) then two cycles are required to complete the instruction This would imply that the goto in the sequence goto next next: or the addwf in the sequence movlw 0 addwf pcl should only take one cycle, since the program counter isn't changed. What they really should have said is that instructions that *may* change the program counter always take two cycles. While we're on the subject, has anyone tested the behavior (on real parts, not a simulator) of writing to the PCL *indirectly*? I.e., movlw pcl movwf fsr movlw label movwf ind ; should take two cycles incf foo ; should not execute ... label: incf bar ; should continue here It wouldn't surprise me one bit if the part didn't notice that the indirect write affected pcl, and actually executed the incf foo. Cheers, Eric

> Luigi Rizzo <.....luigiKILLspam.....LABINFO.IET.UNIPI.IT> writes: > > > after every modification to the PC -- something that the Microchip > > simulator does not do). > > Do you mean that the Microchip simulator only counts one cycle for instructions > that write to PCL? Are they really that inept? > > Of course, the Microchip documentation erroneously states > > If an instruction causes the program counter to change (e.g. GOTO) > then two cycles are required to complete the instruction I was partly wrong. The problem is with the stimulus files, which apparently allows you to change inputs _only_ after an integer number of STEPs (corresponding to instructions, not Tcycles). Since STEPS may las 1 or 2 Tcycles, it is hard to fed the PIC with the exact timing, it depends on what is actually running. At least, this is from the docs; I haven't checked personally. Luigi ==================================================================== Luigi Rizzo Dip. di Ingegneria dell'Informazione email: EraseMEluigispam_OUTTakeThisOuTiet.unipi.it Universita' di Pisa tel: +39-50-568533 via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 http://www.iet.unipi.it/~luigi/ ====================================================================

Luigi Rizzo <PICLISTspam_OUTMITVMA.MIT.EDU> wrote: > I was partly wrong. The problem is with the stimulus files, which > apparently allows you to change inputs _only_ after an integer > number of STEPs (corresponding to instructions, not Tcycles). Since > STEPS may las 1 or 2 Tcycles, it is hard to fed the PIC with the > exact timing, it depends on what is actually running. > > At least, this is from the docs; I haven't checked personally. Luigi: The simulator allows stimulus files to be based either on either instruction steps OR cycles. For details, see the long message I posted to the list a day or two ago. As someone from Microchip (Darrel?) pointed out in a response to that message, the newest version of the simulator (MPLAB-SIM) ONLY allows stimulus based on instruction cycles. -Andy Andrew Warren - @spam@fastfwdKILLspamix.netcom.com Fast Forward Engineering, Vista, California http://www.geocities.com/SiliconValley/2499

> Of course, the Microchip documentation erroneously states > > If an instruction causes the program counter to change > then two cycles are required to complete the instruction > What they really should have said is that instructions that *may* change > the program counter always take two cycles. Rubbish, you can *change* the program counter without *altering* the program counter. ___Bob