Arduino Spi library

[Maker]

I've downloaded the library to use an MCP 4161 digital potentiometer but it needs the Spi library by Cam Thompson, the included SPI library doesn't work.

Does anyone know where I can download this? I can't find it anywhere.

I had it on my old laptop about a year ago so it must exist.

 

[eSCHEn]

The last rev on that code is four years ago. Looks like that spi code has been rolled into arduino core libs.

Compile or runtime errors?

 

[Maker]

The example sketch that comes with the MCP library starts with "#include<Spi.h>", the SPI library that comes with the Arduino IDE is "SPI.h". Changing it to capital so it uses the existing library causes a compiling error.

 

[skotl]

I've never programmed for an arduino but bear in mind that a header in <angle-brackets> is searched for in the include-headers path, whereas a header in "quotes" is looked for in the current directory.

So eSCHEn's point is valid - if it's in the core library then you should probably be using "#include <spi.h>" to refer to the core libs, rather than a version that may have shipped with the sketch.

Finally, I'm guessing the aruino is Linux-based? If so then the paths will be case sensitive so you need to verify the exact spelling of the header file and match the case.
From a Linux shell, either do an "ls -l" or you could try and find all files that are like spi.h, no matter their case, with;

find . -name '[sS][pP][iI].[hH]' -print​

The "." refers to the current directory - you can replace that with an explicit folder name if you like, for example "find /usr/include -name ..."

 

[HughF]

Do you have to use that digital pot?

https://www.arduino.cc/en/Tutorial/DigitalPotControl

 

[MrFluffy]

Could you check it out of github? Not sure if this header file is all you need or you have to work up the tree to find the rest of any dependancies, but its a start.
https://github.com/dkirkby/athomeleaf/blob/master/Spi.h

Skotl, its a Atmel AVR microcontroller onboard, the headers etc are all compiled in on the build computer then transferred to the arduino via flash/jtag etc as compiled for the atml.
He needs the header files to support the sketch being compiled into this. Its all very point and clicky and easy living with friendly names for things if your using the gui client instead of make files and a cross compiler but at its core thats what it is.

 

[daleyd]

\! Other versions of Arduino Spi library (such as `SPI.h`) wont work / wernt tested.

From the bottom of the page you linked to....

 

[Maker]

I've never programmed for an arduino but bear in mind that a header in <angle-brackets> is searched for in the include-headers path, whereas a header in "quotes" is looked for in the current directory.

So eSCHEn's point is valid - if it's in the core library then you should probably be using "#include <spi.h>" to refer to the core libs, rather than a version that may have shipped with the sketch.

Finally, I'm guessing the aruino is Linux-based? If so then the paths will be case sensitive so you need to verify the exact spelling of the header file and match the case.
From a Linux shell, either do an "ls -l" or you could try and find all files that are like spi.h, no matter their case, with;

find . -name '[sS][pP][iI].[hH]' -print​

The "." refers to the current directory - you can replace that with an explicit folder name if you like, for example "find /usr/include -name ..."

I don't have a clue what you mean, I'm quite new to this.

Do you have to use that digital pot?

https://www.arduino.cc/en/Tutorial/DigitalPotControl

Not necessarily, but I already have a couple of them so I'd rather not buy more if possible.

Could you check it out of github? Not sure if this header file is all you need or you have to work up the tree to find the rest of any dependancies, but its a start.
https://github.com/dkirkby/athomeleaf/blob/master/Spi.h

Skotl, its a Atmel AVR microcontroller onboard, the headers etc are all compiled in on the build computer then transferred to the arduino via flash/jtag etc as compiled for the atml.
He needs the header files to support the sketch being compiled into this. Its all very point and clicky and easy living with friendly names for things if your using the gui client instead of make files and a cross compiler but at its core thats what it is.

I downloaded this from your link, unzipped it, put it in the right place and tried to use it but I get:

Arduino: 1.6.5 (Windows 8.1), Board: "Arduino Leonardo"

In file included from Mcp4261Example.pde:4:0:
C:\Users\AHarrington\Documents\Arduino\libraries\athomeleaf-master/mirf.h:30:22: fatal error: WProgram.h: No such file or directory
#include <WProgram.h>
^
compilation terminated.
Error compiling.

 

[HughF]

If I get a spare hour after work tomorrow I'll have a play and see if I can get it to compile. I've been in the same boat before.

 

[Kayos]

I'm same as @skotl I've never touched arduino but it does look like Linux.

When I was interested in making a very very small system I had to strip loads of stuff out and got all sorts of compile errors, most of it was sorted editing the source code and make files but for some stuff I used static linked rather than sym linked libraries (to any proper coders, I know but it worked)

 

[Spot the welders dog]

WProgram used in IDE <v1.0

Does this help?

#if defined(ARDUINO) && ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

 

[eSCHEn]

Scott has is right maker, your include paths are either global with angle brackets or relative / absolute with quotation marks.

I'm just inside to change footwear again as this storm has left a lot of work to do today. If you've not got it sorted by tonight when I'm back on I'll happily walk you through it.

 

[MrFluffy]

I think Spot has it, its not picking up WProgram.h because thats how the Arduino IDE used to do it. This is exactly what I meant by spending some time looking at the dependancies (includes) as I wondered if that was still about. It might strike you that I've been uncharitable not pointing that out earlier having spied it, however your learning, and this is one of the important things to understand. I spend most of my time when compiling older stuff frigging round fixing includes or porting things to work with different versions of libraries.

You can either find and feed it WProgram.h somehow, put it in the path, absolute include path or whatever, or maybe someone can fettle it to work with the later version.
In the meantime also worth investigating what happens if you change WProgram.h for Arduino.h in the include directive, as arduino might have the same interfaces and specs and just did a renaming/branding exercise.

Theres a name for the issues that come from using a older version of something, its known as "bitrot" in programming circles.
You go to build something from a few years back and if its been abandoned the includes and library interfaces have changed and it no longer works out the box and needs a bit of fiddling with.
I've only ever used my arduino as a flash programmer for some AVR boards using the ArduinoISP sketch so not much more hands on inside them apart from doing that one day when I didnt have a programmer to hand, but the above concept and issue are in use right over the programming spectrum.

 

[eSCHEn]

Well put sir.

Old code can (and frequently is) a poo faced cow to get working.

Bearing in mind that I've never used an arduino or its IDE (web based isn't it?), what I would be doing is following the includes in the headers and either move your source tree to match or add an include path(s).

The choice of which one is usually determined by whichever means the least work for me.