Code won't run within init.m

Questions
,
1

I have a Raspberry Pi connected via a USB serial connection to an Arduino Uno, which is connected to an AM2302 humidity/temperature sensor. I am able to read the data from the sensor into Mathematica and then send the data by email and to a web server. No problems if I run the code within a Notebook.

My next step is to put the code into my init.m file (which is in /usr/share/WolframEngine/Kernel) so that it runs when I start Mathematica. This is where I run into a problem. The code starts to evaluate fine, with an email message letting me know, but then I get these messages:

    Import::format: Cannot import data as HeldExpressions.
    
    DeviceOpen::noclass: 
       A driver for Serial was not found on your local computer or currently
         available paclet sites. If you can locate the driver, add the driver
         directory to $Path or load the driver directly with Get. If you cannot
         locate the driver, contact the device manufacturer or create a driver
         using the Wolfram Device Framework. See http://devices.wolfram.com for
         more information.

The code that worked in the Notebook is the only thing that is in init.m, so it isn’t a matter of a conflict with other code.
The serial connection I successfully make within the Notebook version is

    port = "/dev/ttyACM0"
    dev = DeviceOpen["Serial", {port, "BaudRate" -> 9600}];

Any idea what’s going on

Ken Levasseur
UMass Lowell

2

Is this the same directory as

FileNameJoin[{$UserBaseDirectory, "Kernel"}]

(I actually have no idea about Raspberry Pi s, etc… just offering the location where I put revised init.m things on my laptop Mathematica.)

3

David:

Yes, the value of $AddOnsDirectory in the Raspberry Pi version of Mathematica is

/usr/share/WolframEngine/Kernel

The init file evaluates, but for some reason, the Serial connection doesn’t get established when I try to do it as part of init.m.

4

Not all functionality is completely initialized and available to use during the early stages of kernel startup.

Try using the following in init.m instead:

task := (...);  (* code to be executed *)
RunScheduledTask[task, {1}]
5

Thanks Ilian, it hadn’t occurred to me that the serial connection wasn’t initialized. I simply put my code into a package and I delayed running it a minute within a ScheduledTask. It worked!