[fpc-pascal] USB Human Interface Devices

[James Richters]

Thank you for adding the timeout!  That will work for this project, but I may look into threads in my console program,  I could simplify a lot of things where I am maintaining a buffer while something else is being fed by the buffer that would probably be a lot easier if I had threads.

I've got the read working and have decoded all the buttons and switches on my device, but I still can't write to the display... well not on purpose.. something wrote a bunch of garbage to it at some point, which it is remembering.

The problem I am going to have with the LCD is that this device is not the exact one that I have sample code for.. when I decoded all my buttons and switches I realized that I was getting NOTHING like the sample.  The sample is for an HB04 and this is a WHB04B,   the W is just for wireless.. but the B is a completely different thing..  unfortunately I can't seem to even buy the original one without the B without waiting for a month for it to get here from China... I ordered one today.. but maybe before it gets here I'll figure out some way to just blast data to this one until something happens on the screen, and then I can figure it out.  

Thanks for the help with all this!!

James

-----Original Message-----
From: fpc-pascal <fpc-pascal-bounces at lists.freepascal.org> On Behalf Of Stefan V. Pantazi
Sent: Friday, August 16, 2019 1:30 PM
To: fpc-pascal at lists.freepascal.org
Subject: Re: [fpc-pascal] USB Human Interface Devices


On 8/16/19 11:11 AM, James Richters wrote:
>>> Remember that interrupt reads are  blocking so the way to deal with 
>>> them is to put them away from the main thread, in their own thread. 
>>> The moment something is available from the device, then the main 
>>> thread of your application is signaled to read a buffer with the 
>>> device report data. So, I can see some thread programming in your 
>>> future or,

I see I did not finish my sentence. What I had in mind is that you could use a library that already implements (using a thread I assume) a call with a timeout. I checked and it looks like the original libusb call that I used did have a timeout parameter that I hardcoded to 0 (infinite timeout). libusb report a timeout as an error code. That did not sit well with me and I preferred to use threads instead of time-out mechanism.

 > Is there another way to do a read that has a timeout?

yes, it took only a few minutes to add the time-out parameter to the libusbhid_interrupt_read call. Have a look at the github repository for the updated version.

> 
> Can I even do threads in a console program?   

Sure you can, here is one of the simplest example you can start with should you ever need to have multiple threads in your programs.

https://github.com/graemeg/freepascal/blob/master/packages/fcl-base/examples/threads.pp


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