From: Bob Blick <bobblick@outlook.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
Sender: "piclist-bounces@mit.edu" <piclist-bounces@mit.edu>
Date: Thu, 30 Jul 2020 11:04:05 -0700
Subject: Re: [PIC] Simple GCC question
Thread-Topic: [PIC] Simple GCC question
Thread-Index: AQHWZotc+nNhZovUu0iBK4Bhj1/IWakgV02AgAAINQWAAAbfgIAAA3fr
Message-ID:
 <BYAPR02MB4055CAA482C1DA734252C3C3DC710@BYAPR02MB4055.namprd02.prod.outlook.com>
References:
 <BYAPR02MB405521AE3E1393B371E463FDDC710@BYAPR02MB4055.namprd02.prod.outlook.com>
	<CAHFNz9K7LVg=L25mYPVh16nSvf2EEH_+A6_tssvKGgRE1z6gWg@mail.gmail.com>
	<BYAPR02MB4055B7ACF17F19A86CA8C49BDC710@BYAPR02MB4055.namprd02.prod.outlook.com>,
	<CAHFNz9JmsMPY-wuRJi6LB1pnUA_VJSugk_+OUcFseGXwHsNjig@mail.gmail.com>
In-Reply-To:
 <CAHFNz9JmsMPY-wuRJi6LB1pnUA_VJSugk_+OUcFseGXwHsNjig@mail.gmail.com>
Reply-To: Microcontroller discussion list - Public. <piclist@mit.edu>
Accept-Language: en-US
Content-Language: en-US
X-MS-Exchange-Organization-SenderIdResult: TempError
X-MS-Exchange-Organization-PRD: mit.edu
X-MS-TNEF-Correlator:
acceptlanguage: en-US
received-spf: Pass (protection.outlook.com: domain of outlook.com designates
	40.92.4.25 as permitted sender) receiver=protection.outlook.com;
	client-ip=40.92.4.25; helo=NAM02-CY1-obe.outbound.protection.outlook.com;
dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=outlook.com;
	s=selector1;
	h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck;
	bh=8eN1bKFEPK87JnVdy3dtyUddPw3kWkjnMtBnHm/ZVyU=;
	b=PanfOp01p4EED38Ba8ttWPuuEI90WAY51M1ktAjryy9WKM7ovRLgIv+5pThintIJImYGFFoF5noieuyGeBi6WD+JGvWsFC6uXWX2+wkZRD8bAq0pl3Mox9EbS2pVVpXOxo5AzgUNsLZJpvFOq20tSrU6oJAZo7qL5U6v8i5HfFiw+ilgWdQnHXcq53v7Zs/gKDcwu9zEQX0J0F/+8nDzW/ykTiNORtyp6EHM4zwSoh9zUl1u7ssRGxCa92ddw2I93iju4aGOHwhmOVFWeFe+bs3AimbCnL4s2rRXy/J72E+KLzWYgy17YWnhtTCvOzkHnH6DmR1GdXIa0F14hiQdIA==
authentication-results: spf=pass (sender IP is 40.92.4.25)
	smtp.mailfrom=outlook.com; mit.edu; dkim=pass (signature was verified)
	header.d=outlook.com; mit.edu;	dmarc=pass action=none
 header.from=outlook.com; 
errors-to: piclist-bounces@mit.edu
list-id: "Microcontroller discussion list - Public." <piclist.mit.edu>
list-post: <mailto:piclist@mit.edu>
x-beenthere: piclist@mit.edu
x-mailman-version: 2.1.6
x-topics: [PIC]
x-mime-autoconverted: from quoted-printable to 8bit by PCH.mit.edu id
	06UI4V0F027055
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0

Hi Manu,
I will give it a try. I guess I wasn't just too stupid not to be able to ma=
ke it work without changes. Thank you very much.
Bob

________________________________________
From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> on behalf of Manu A=
braham=20
Sent: Thursday, July 30, 2020 10:49 AM
To: Microcontroller discussion list - Public.
Subject: Re: [PIC] Simple GCC question

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  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.
>
> --
>

--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.