From: Neil <picdude3@narwani.org>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Thu, 30 Jul 2020 10:10:46 -0700
Subject: Re: [PIC] Simple GCC question
Thread-Topic: [PIC] Simple GCC question
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Bob,

Strange way to do this IMO... I would keep ports & pins together in a=20
struct for each GPIO, then group those together for your call to=20
lcd_create().
Either way, I'm not sure why gcc thinks your port and pin definitions=20
aren't constants.  Aren't you using CMSIS for those definitions?
In HAL (which ultimately uses CMSIS), ports and pins are defined in the=20
mail header file like this...
#define LED_Pin GPIO_PIN_13
#define LED_GPIO_Port GPIOC

Then these are further defined in a deeper file as:
#define GPIO_PIN_13                ((uint16_t)0x2000)  /* Pin 13=20
selected   */
and...
#define GPIOC               ((GPIO_TypeDef *)GPIOC_BASE)
and then...
#define GPIOC_BASE            (APB2PERIPH_BASE + 0x00001000UL)
and also...
/*!< Peripheral memory map */
#define APB1PERIPH_BASE       PERIPH_BASE
#define APB2PERIPH_BASE       (PERIPH_BASE + 0x00010000UL)
#define AHBPERIPH_BASE        (PERIPH_BASE + 0x00020000UL)

....which are constants.

How/where do you have your ports and pins defined?

Cheers,
-Neil.




On 7/30/2020 12:50 PM, Bob Blick wrote:
> Hi Sean,
>
> Here it is:
>
> https://github.com/4ilo/HD44780-Stm32HAL
>
> Thanks, Bob
>
> ________________________________________
> From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> on behalf of Sean=
 Breheny
> Sent: Thursday, July 30, 2020 9:38 AM
> To: Microcontroller discussion list - Public.
> Subject: Re: [PIC] Simple GCC question
>
> 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  wrote:
>
>> I'm using a nice little HD44780 LCD library in an STM32 project, it work=
s
>> 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
>> 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_Pi=
n};
>>    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 wo=
uld
>> 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
>

--=20
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