Re: STM32F4 Discovery, communication and libraries

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Wed, 10 Sep 2014 10:46:49 -0700, Jeffrey Carter wrote:

> On 09/10/2014 07:11 AM, Stephen Leake wrote:

>> Way overkill. Global variables is all you need.
> 
> While a publish/subscribe mechanism is probably overkill, global variables
> should never be used. Global variables are a guaranteed way to make your S/W
> hard to understand and modify.

Not really overkill. Much depends on the protocol role the application must
play. If the application is a master it could control slaves from the main
control loop, forcing them to send or accept data. But if it is a slave,
many protocols require slaves or are time triggered or are not
client-server at all, then it has no say when data arrive or go. A
publisher/subscriber service resolves this. The global variables pool does
this too, but it has issues with data consistency, e.g. logically coherent
variables, one updated, one not. Even bigger problems arise with
non-physical valued variables, when you must handle each variable update.
All commands are like that. With global variables it quickly ends up with
toggle bits and other mess.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de