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What is the purpose of acquire_bus(), release_bus() functions?


zaher

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Hello everyone!

I'm almost done adding uGFX to an existing project and now all I need to do to get up and running is to finish the driver glue functions for my LCD. Fortunately, when  I came here first time few years ago, the SSD1322 was not supported. Now that has changed and the driver is part of the official repository. 

Well, I did not try it yet, but out of curiosity and just to make sure everything works out from first time, what is the purpose of the following functions:

acquire_bus(GDisplay* g), release_bus(GDisplay* g), post_init_board(GDisplay* g)

 

And why most of these functions, including the write data/command ones, take a pointer of GDisplay type as a parameter? What it does exactly? 

 

Thank you!

 

Zaher

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The display controller is physically connected to your microcontroller/system via some kind of bus. For example parallel or SPI. The acquire_bus() and release_bus() functions are called by the driver itself (which is independent from what interface/bus is being used) before and after making a bus transaction. These functions allow you to acquire the bus before talking on it and releasing it once you're done.

In case of a simple SPI interface this is where you want to set your CS pin level accordingly. More complex systems might need to call OS functions to acquire/request bus access and stuff like that.

The GDisplay structure represents the actual display. You can have a look at the documentation to figure out what information is contained. Usually you're interested in this when dealing with multiple displays or requiring the private board file area.

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More information...

Aquire_bus and release_bus give you an opportunity to use a shared bus.

Post_init is called once the controller has been initialised. Many controllers need to be initialised at a slower bus speed. Post_unit gives you the opportunity to increase the bus speed after the controller is initialised.

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Thank you guys for the prompt follow up. I guess I'm all set now. I did not touch those functions, and now the display shows the following when initialized:

Photo.thumb.png.21a189e7f06bcc2dc3a1728d889db210.png

I believe the aforementioned functions are more relevant when a parallel bus is used (FSMC). Since I'm using the SPI and everything was done earlier, I guess I'm good to go.

By the way, how to remove this splash screen or it is necessary everytime the system starts up?

Thank you again!

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