Arduino type libraries

[HenrikOlsson]

It's not very easy to do with PBP due to all variables being global and the lack of proper function calls where you can pass parameters.

Just one very basic example:
Say I write a "library" for a GP2Y0A21 distance sensor and I decide to create a variable called Distance. Then you create a "library" for driving a motor with encoder feedback and you decide to create variable called Distance. Then comes the "user" and finds our, on their own, great "libraries" and wants to use them on his/her new robot. Well, you know what happens.

/Henrik.

[picster]

Hi Henrik,

Agreed, you can't fix stupid... but having said that, if the variables for each are commented at the very onset, then the "user" can certainly take the time to compile a list and change any required with a simple search/replace, no?

picster

[Scampy]

Not quite library files, but PBP does have the function to include files, so you could have a "library" file for a function, such as setting up an LCD or using a specific sensor, and then use one line of code in the main file to include that file as part of the main code, but it has the same limitation Henrik mentioned, in that you have to name the variables carefully. It really helps developing your own projects as you know what the variables are called, but to offer them as a general use for different project could cause confusion.

[HenrikOlsson]

I believe the USERCOMMAND stuff is much closer to what's needed but unfortunately you have to resort to assembly language to use it and there's zero documentation for it in the manual, what's available is what Darrel has posted.

When I write PBP code that I may use in multiple projects I try to use some sort of prefix in my variables. I have a MODBUS Engine and every variable and constant (and usually subroutines) that "belongs" to it is named like MB_Address, MB_Function etc. In my PID "library" all the variables are named PID_Kp, PID_Status, PID_Error etc, I have code that accesses external memory device, when I wrote that I settled on prefexing variables with XEE_ so that I can replace the actual routines accessing the memory device without changing the main program.

It's "workable" but it's FAR from proper function calls, where you can say Average=CalculateAverage(3,10,20,30). For a user to use that library routine, all he has to know is what parameters to pass and what it returns. Trying to do the same in PBP would force the user to lookup the names of the various variables used internally in the CalculateAverage subroutine, load them with values "manually", GOSUB the routine and then, possibly, copy the result from routines "outputvariable" to his own variable, ie Result.

Avg_NumberOfVaules = 3
Avg_Value_1 = 10
Avg_Value_2 = 20
Avg_Value_3 = 30
GOSUB Avg
Average = Avg_Output

This also means that since all variables are global and "in scope" all the time nothing is stopping/helping the user from messing about with variables INSIDE the CalculateAverage subroutine that he really should not need to worry about or have to care about. There are tradeoffs with everything of course.

Writing re-usable code in PBP is hard when you're doing it for yourself, it's even harder if you're trying to do it for the benefit of others.

Local variables and proper function calls has been a requested feature but Melabs says it's never going to happen because PBP isn't written with that in mind from the get-go. I've said that it was totally fine with the 16F84 and its 68bytes of RAM, having the overhead of a software stack etc would be "bad". But now when devices have 500 times as much RAM it's getting hard to manage large projects when EVERYTHING is global. But again, it does have its upsides too of course.

/Henrik.

[pedja089]

I always use include name in front of variable allocated in that include. Eg for ADS1248 include, all variable start with ADS_.
And I create TempB1 var byte,TempB2,3... TempW1 var word..., TempL1 var long... variables in main file of project, and use them for intermediate calculation in all includes and main file. And there variables are newer used in interrupts.
Pin defines are always commented in include file, so I just copy them in main file and write appropriate port names.
Main project file:

 
    TRIS ADCON OSCCON etc register ...
   
'Temporally variables used everywhere
    TmpL1       VAR LONG
    TmpL2       VAR LONG 
    TmpB0       VAR BYTE
    TmpB1       VAR BYTE
    TmpB2       VAR BYTE
    TmpB3       VAR BYTE
    TmpW        VAR WORD
'Variables for project

'Defines for ADS
    SYMBOL ADS_DOUT = PORTE.2
    SYMBOL ADS_SclK = PORTE.3
    SYMBOL ADS_DIN = PORTE.4
    SYMBOL ADS_DRDY = PORTE.5
    SYMBOL ADS_CS = PORTE.6
    SYMBOL ADS_RESET = PORTE.7
    INCLUDE "ADS1248.pbp"

For calling functions I use this
AdsRegAdr=AdsIDAC0: AdsRegVal=%00000111: GOSUB ADS1248WriteRegister
GOSUB ADS1248ReadResult
IF ADS_Result.15=0 THEN..
So it isn't inconvenience, and looks like functions...

I done few includes that I used in multiple projects, and I don't see any major drawback comparing to C. There project are commercial, so I cant share my work.
Also I'm working on WEB server for PIC in my free time, and I had made DHCP just as include file, and to exclude or include just use #IF. That project should be published here when I finish it.

[picster]

I find that documenting my variables and keeping track of them (with multiple modular includes) is one of the most challenging things. I usually create a modular include (sub) if it performs a task/function that I think I'll use again - and just comment it to death - but the idea of having a variable naming convention with a prefix indicating the INCLUDE NAME is a really good idea.

[Heckler]

Though I have never worked with an arduino board...

It occurs to me that one must realize (and you probably do) that the Arduino is based on a specific set of pinout functions. It is just a microcontroller on a very defined PCB with pin functions that are limited to what the PCB is set up for. ie. certain pins set for digital and certain other pins set for analog, etc.

So in order to use someone else's library you must use the same pins that they did (unless the library is written to allow you to choose different pins)

Whereas the group of contributors here are using a VERY WIDE RANGE of PIC microcontrollers. Not just one or two that would fit an arduino like model.

So I believe your best bet would be to use the search function to locate examples of code that will allow you to do what you want to do with your chosen PIC.

It seems to me that the only way to be able to use libraries or in PBP it would be "Include" files we would have to agree on a set of standard pin assignments and limit ourselves to just a few similar PIC's.

While I think your wish is valid and would be nice it is a bit unrealistic for such a broad range of microcontrollers that PBP works with.

That is obviously just my opinion and I would love to be wrong
dwight

[Dave]

I agree Dwight.....

[picster]

I try to use aliases typically, to designate pins. Provided that proposed "Code Libraries" use aliases as a rule of thumb (instead of specific pins), this would alleviate much of the "broad range" issue, would it not? Each user could then have their own specific alias definitions for assigning pins/ports. Data direction registers, Port and pin assignments, etc. would all be up to the user to define, so that the aliases within the "Library" are adapted to his/her PIC of choice. If requirements are documented within each Library, then users can ensure they allocate resources accordingly.

I realize that it's far from perfect, but in the interest of evolution toward standardized code snippets, doesn't it seem like something worth starting?