VSM preferances

[Timbo]

Hi,

As part of my move to get my coding going again, I'm looking at buying a Labcenter VSM package for the Pic 24. I have an old licence for the Pic 18/16/14/12/10 series but will need to keep them separate as I would need to update the lot and that would be very expensive.

Then I thought what about Mplabs. I see some of you guys use Mplabs so wanted to know what your thoughts were. I do really love the simplicity of Labcenter and what I can do with it. But maybe Mplabs is worth the effort to learn.

Really I doubt I will do much VSM ing as its so easy using the Firewing board but love the way I can step through and see exactly what is happening in ISIS.

Any thoughts?

Cheers

Tim

[Jerry Messina]

I find debugging with MPLAB to be indispensable. However, it's very different from ISIS... it's not a circuit simulator so you don't have virtual components and such, but it does have other advantages.

MPLAB has a built-in PIC simulator that lets you run your program on a virtual PIC. It usually does a decent job simulating "code" but it's limited in IO features. You can do simple things like set and observe pin states, but it doesn't cover a lot of the peripherals except for UART1.
You can work at the source code level or view things in assembly, set variable watches, execution breakpoints, run, step, etc. I use it mainly for debugging software algorithms.

Then there's the ICD debugger interface. It looks a lot like the simulator with a few different features. Here you use one of the programmers such as the PICKit3 or ICD3 connected to the same ICSP connections that you use to program the chip. The ICD lets you load your code onto the chip and run it on an actual device. This way you can see how your code interacts with real hardware.

The nice thing is that it's all free (except for the ICD of course) so all it costs is some time to try it out. There are two versions of MPLAB available... the older MPLAB v8.92 and the "new" MPLABX. For the time being I'd recommend sticking with the original MPLAB as they're still working out some of the kinks.

One of my main complaints with simulators in general is the fact that you never know how well the simulator actually represents the part(s). You can have bugs in the model, bugs in the device that aren't in the model, limitations in the model, etc, so once you've done the simulation you can still have issues. I don't mind using a free one, but I'm not sure I'd pay money for one esp. since there are other options. I can live w/out simulating how my LCD works!

[Timbo]

HI Jerry

Thanks for the clarification on how you use Mplabs. I should try it.

I have found isis invaluable. Its so easy to use, just plonk a chip down, point it to the code and your off. Most of the time I use it like you said for algo checking but I also do timing checks and simulating inputs.

I had one job that needed 4 x RS232 at 9600 packetized to 115200. In the end I had 9 pics VSM ing at once 4 simming sending the data, 4 collecting it and 1 sending it out to a terminal prog. I would not have been able to get the inter pic coms working without ISIS.

In general I simulate the external inputs like voltages and inputs something I cannot do in Mplabs. I will need to see how I get on with normal debugging to see if spending the £400 in the VSM for the 24 series is worth it.

[Jerry Messina]

to see if spending the £400 in the VSM for the 24 series is worth it

Ouch! Thanks a serious chunk of change, Tim, but I know what it's like getting used to using a tool and then not having it anymore.
I can see where simulating a bunch of hardware has it's advantages... that'd be a pain trying to do with the just the ICD.

MPSIM definitely isn't a replacement for ISIS, but it isn't totally useless either. The MPLAB Users Guide has a chapter on MPSIM...
maybe check it out http://ww1.microchip.com/downloads/en/DeviceDoc/MPLAB_User_Guide_51519c.pdf