From: Sean Breheny <shb7@cornell.edu>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Thu, 30 Jul 2020 09:38:26 -0700
Subject: Re: [PIC] Simple GCC question
Thread-Topic: [PIC] Simple GCC question
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Hi Bob,

Do you have a link to the library you are using? I don't understand what
the type of LCD_D4_GPIO_Port, etc. is.

Sean


On Thu, Jul 30, 2020 at 12:27 PM Bob Blick <bobblick@outlook.com> wrote:

> I'm using a nice little HD44780 LCD library in an STM32 project, it works
> great but I'm stuck with a variable scope problem that I can only seem to
> make worse because GCC is a bit stricter than I want it to be at this
> point. Sorry if the code example doesn't wordwrap properly.
>
> If, somewhere in main() I create an instance of the LCD like this:
>   Lcd_PortType ports[] =3D {LCD_D4_GPIO_Port, LCD_D5_GPIO_Port,
> LCD_D6_GPIO_Port, LCD_D7_GPIO_Port};
>   Lcd_PinType pins[] =3D {LCD_D4_Pin, LCD_D5_Pin, LCD_D6_Pin, LCD_D7_Pin}=
;
>   Lcd_HandleTypeDef lcd =3D Lcd_create(ports, pins, LCD_RS_GPIO_Port,
> LCD_RS_Pin, LCD_EN_GPIO_Port, LCD_EN_Pin, LCD_4_BIT_MODE);
>
> then I can use it like this:
>   Lcd_cursor(&lcd, 1,6);
>
> but of course I can't do that from within another function since "lcd"
> only exists in main()
>
> If I try to make it all global by creating lcd outside of main(), GCC
> doesn't like that because initializer elements must be constants and it
> doesn't consider "ports" and "pins" to be constants.
>
> Not being a real C programmer this has stopped me in my tracks. If I was
> stuck on a deserted island I would use this library as a basis for
> something with ports and pins hardcoded, but I'm hoping a real expert wou=
ld
> give me some gentle help, which will certainly educate me about doing
> things the correct way and also get me past this little hurdle.
>
> Thanks, Bob
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