From: Manu Abraham <abraham.manu@gmail.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Thu, 30 Jul 2020 10:49:13 -0700
Subject: Re: [PIC] Simple GCC question
Thread-Topic: [PIC] Simple GCC question
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Hi Bob,

Another look at the github code, I would do this:

#define MODE ..

#define EN_PIN    LL_GPIO_PIN_0
#define EN_PORT GPIOB
...
and more

Lcd_HandleTypeDef lcd;  <-- make this global,

int main(void)
{

... do whatever ..

lcd.mode =3D MODE;

lcd.en_pin =3D EN_PIN;
lcd.en_port =3D EN_PORT;

lcd.rs_pin =3D rs_pin;
lcd.rs_port =3D rs_port;

lcd.data_pin =3D pin;
lcd.data_port =3D port;

Lcd_init(&lcd);

... do whatever ..

}

Lcd_init() happens to be public via lcd.h.
So, you do not need to clobber the library,
but just that you do not need to call Lcd_create() fn.

Advantage, lower memory usage, lesser complexity. :-)

Regards,
Manu

On Thu, Jul 30, 2020 at 11:08 PM Bob Blick <bobblick@outlook.com> wrote:
>
> Hi Manu,
>
> Although the LCD will not normally be driven from interrupts, if there is=
 a lockup I would like it to leave an error code on the display, which woul=
d need to be done from an interrupt.
>
> I guess to make it global without errors I will need to hardcode the port=
s and pins so I get rid of the arrays that are handed to Lcd_create()
>
> Thanks, Bob
>
> ________________________________________
> From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> on behalf of Manu=
 Abraham
> Sent: Thursday, July 30, 2020 9:55 AM
> To: Microcontroller discussion list - Public.
> Subject: Re: [PIC] Simple GCC question
>
> On Thu, Jul 30, 2020 at 9:57 PM Bob Blick wrote:
> >
> > I'm using a nice little HD44780 LCD library in an STM32 project, it wor=
ks great but I'm stuck with a variable scope problem that I can only seem t=
o make worse because GCC is a bit stricter than I want it to be at this poi=
nt. 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_Pi=
n};
> >   Lcd_HandleTypeDef lcd =3D Lcd_create(ports, pins, LCD_RS_GPIO_Port, L=
CD_RS_Pin, LCD_EN_GPIO_Port, LCD_EN_Pin, LCD_4_BIT_MODE);
> >
>
> Why I dislike opaque datatypes...
>
> Instead of copying objects to Lcd_create(), a pointer could have been use=
d,
> storage could have been global, made static ..
> the variables appear to be for configuration purposes ?
>
> One way to do is make the lcd object global.
>
> Another way is to pass a lcd object pointer to whatever function you
> are calling,
> unless you need to access the lcd object from interrupt context.
> If you need access from interrupt context, the easier way is to have
> global storage.
>
> --
>
> --
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> http://mailman.mit.edu/mailman/listinfo/piclist

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