topic Re: GPIO Speed in LPCXpresso IDE

GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:42 GMT

Content originally posted in LPCWare by dirtyBits on Sun Apr 24 07:26:17 MST 2011
I'm trying to figure out the maximum toggle speed supported by LPCXpresso LPC1343.

Here is my code;

#include "LPC13xx.h"
#include "gpio.h"
#include <cr_section_macros.h>
#include <NXP/crp.h>
__CRP const unsigned int CRP_WORD = CRP_NO_CRP ;

#define LED_PORT 0// Port for led
#define LED_BIT 7// Bit on port for led
#define LED_ON 1// Level to set port to turn on led
#define LED_OFF 0// Level to set port to turn off led

int main(void) {

 GPIOInit();
 GPIOSetDir( LED_PORT, LED_BIT, 1 );

 while(1)
 {
  GPIOSetValue( LED_PORT, LED_BIT, LED_ON );
  GPIOSetValue( LED_PORT, LED_BIT, LED_OFF );
 }
return 0 ;
}

and here is the output;

[IMG]http://i53.tinypic.com/33w5k5j.jpg[/IMG]

it's < [B]1 MHz[/B] :confused: [SIZE=2][FONT=Arial Black][B]How to speed this up??[/B][/FONT][/SIZE] :cool:

Regards

PS: It's my first program on LPCXpresso and just exploring it. So plz help me learn!

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:43 GMT

Content originally posted in LPCWare by Ex-Zero on Sun Apr 24 07:46:25 MST 2011
This issue was discussed before for LPC1769 :)

See and learn:

http://knowledgebase.nxp.trimm.net/showthread.php?t=1805

Note: Use Optimization -02 and control disassembly view

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:43 GMT

Content originally posted in LPCWare by dirtyBits on Sun Apr 24 12:46:34 MST 2011

Quote: Zero
This issue was discussed before for LPC1769 :)

See and learn:

http://knowledgebase.nxp.trimm.net/showthread.php?t=1805

Note: Use Optimization -02 and control disassembly view

I have gone through the post and datasheet/user guide for LPC13xx but still not sure how to use LPC_GPIO0 and IODIR functions for LPC1343.

To set pin 22 of LPC17xx to GPIO, its LPC_PINCON->PINSEL1 &= (~(3 << 12));
To set pin 22 of LPC17xx to GPIO to be output its, LPC_GPIO0->FIODIR |= (1 << 22);

But how to set;
1. Pin 7 of LPC1343 to GPIO
2. Pin 7 of LPC1343 to Output
3. Pin 7 of LPC1343 to set HIGH(1) or Clear LOW(0) ?

Also how this [B]GPIOnDIR and GPIOnDATA[/B] is used??

Appreciate your help....
:)

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:44 GMT

Content originally posted in LPCWare by Ex-Zero on Sun Apr 24 13:07:18 MST 2011
Select a function (double click) and use F3 to jump to its declaration.
That should lead you to gpio.c in LPC13xx_Lib,where these functions are declared and explained.

A few basic Eclipse functions are explained in Literature section of

http://ics.nxp.com/lpcxpresso/

Especially:
Learn Eclipse the LPCXpresso Way - From the Developers

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:45 GMT

Content originally posted in LPCWare by dirtyBits on Sun Apr 24 14:04:40 MST 2011

Quote: Zero
Select a function (double click) and use F3 to jump to its declaration.
That should lead you to gpio.c in LPC13xx_Lib,where these functions are declared and explained.

A few basic Eclipse functions are explained in Literature section of

http://ics.nxp.com/lpcxpresso/

Especially:
Learn Eclipse the LPCXpresso Way - From the Developers

Okay some progress..
Found out that the value of DIR and DATA is not required as in following code:

#include "LPC13xx.h"
#include <cr_section_macros.h>
#include <NXP/crp.h>
__CRP const unsigned int CRP_WORD = CRP_NO_CRP ;


#define LED_ON  LPC_GPIO0->DATA |= 0x080;
#define LED_OFF LPC_GPIO0->DATA &= 0xF7F;

int main(void) 
{
LPC_GPIO0->DIR |= 0x080; // Configure Pin 0_7 as output

 while(1)
 {
  LED_ON;
  LED_OFF;
 }
return 0 ;
}

But I'm still in debug mode and toggle speed is [B][SIZE=3]2 MHz[/SIZE][/B]

I'll try in release mode and will post you the result...
Thanks

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:46 GMT

Content originally posted in LPCWare by Ex-Zero on Sun Apr 24 14:18:17 MST 2011
1.If you want to use a pin as output switch to output:

  LPC_GPIO0->DIR = (1<<7);

2. Don't use '|=' and '&=' if you expect speed. Use a simple direct write without reading the register before:

#define LED_ON  LPC_GPIO0->DATA = (1<<7);
#define LED_OFF LPC_GPIO0->DATA =~(1<<7);

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:46 GMT

Content originally posted in LPCWare by jharwood on Sun Apr 24 14:34:18 MST 2011
Or use gpio masked access

#define LED_ON  LPC_GPIO0->MASKED_ACCESS[(1<<7)] = (1<<7);
#define LED_OFF LPC_GPIO0->MASKED_ACCESS[(1<<7)] =~(1<<7);

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:47 GMT

Content originally posted in LPCWare by dirtyBits on Sun Apr 24 14:41:18 MST 2011

Quote: Zero
1.If you want to use a pin as output switch to output:

  LPC_GPIO0->DIR = (1<<7);

2. Don't use '|=' and '&=' if you expect speed. Use a simple direct write without reading the register before:

#define LED_ON  LPC_GPIO0->DATA = (1<<7);
#define LED_OFF LPC_GPIO0->DATA =~(1<<7);

Yes indeed...it speeds up a bit,
here is the new code;

#include "LPC13xx.h"
#include <cr_section_macros.h>
#include <NXP/crp.h>
__CRP const unsigned int CRP_WORD = CRP_NO_CRP ;


#define LED_ON  LPC_GPIO0->DATA =  (1<<7);
#define LED_OFF LPC_GPIO0->DATA = ~(1<<7);

int main(void)
{
LPC_GPIO0->DIR = (1<<7); // Configure Pin 0_7 as output

 while(1)
 {
  LED_ON;
  LED_OFF;
 }
return 0 ;
}

I'm getting [B][SIZE=2]6 MHz[/SIZE][/B] toggle speed with the modification of the code in Release mode and [B][SIZE=2]4 MHz[/SIZE][/B] with previous code.

[SIZE=2][B]@Zero[/B][/SIZE] Thanks a lot with your help and support!
Really appreciate!

However still not happy with only [B][SIZE=2]6 MHz[/SIZE][/B] with a [B]72MHz[/B] processor my expectations are much higher!!
:cool:

Results are as follow;
[IMG]http://i52.tinypic.com/qpfnl0.jpg[/IMG]

[IMG]http://i53.tinypic.com/jkj33r.jpg[/IMG]

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:47 GMT

Content originally posted in LPCWare by dirtyBits on Sun Apr 24 15:13:02 MST 2011

Quote: jharwood
Or use gpio masked access

#define LED_ON  LPC_GPIO0->MASKED_ACCESS[(1<<7)] = (1<<7);
#define LED_OFF LPC_GPIO0->MASKED_ACCESS[(1<<7)] =~(1<<7);

Tried that too..getting the same result for the speed!
However i tried putting multiple sequence of ON and OFF together which obviously speeds the things up. and now getting [B][SIZE=2]12 MHz[/SIZE][/B] with LPC 1343.
Is this [SIZE=2]right[/SIZE] or am I getting this results because my Logic analyzer can measures max up to [B]24 MHz?[/B] [B][SIZE=2]Plz advice.[/SIZE][/B]

code;

#include "LPC13xx.h"
#include <cr_section_macros.h>
#include <NXP/crp.h>
__CRP const unsigned int CRP_WORD = CRP_NO_CRP ;

#define LED_ON  LPC_GPIO0-> DATA = (1<<7);
#define LED_OFF LPC_GPIO0-> DATA =~(1<<7);

int main(void)
{
LPC_GPIO0->DIR = (1<<7); // Configure Pin 0_7 as output

 while(1)
 {
  LED_ON;
  LED_OFF;
  LED_ON;
  LED_OFF;
  LED_ON;
  LED_OFF;
  LED_ON;
  LED_OFF;
  LED_ON;
  LED_OFF;
  LED_ON;
  LED_OFF;
  LED_ON;
  LED_OFF;
  LED_ON;
  LED_OFF;
 }
return 0 ;
}

Results;
[IMG]http://i52.tinypic.com/o0qlqr.jpg[/IMG]

Thanks in advance.

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:48 GMT

Content originally posted in LPCWare by Ex-Zero on Sun Apr 24 15:18:43 MST 2011
You need faster code :mad:

So select Optimization -O2 and the compiler is creating faster code.

My DSO shows 18MHz :)

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:49 GMT

Content originally posted in LPCWare by dirtyBits on Sun Apr 24 15:20:54 MST 2011

Quote: Zero

select Optimization -O2

[SIZE=2][B]How??[/B][/SIZE]
:eek: 18Mhz !!??

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:49 GMT

Content originally posted in LPCWare by Ex-Zero on Sun Apr 24 15:27:51 MST 2011
Right click on project and select Properties.

Change Properties-> C/C++ Build-> Settings -> Tool Settings ->MCU C Compiler -> Optimization

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:50 GMT

Content originally posted in LPCWare by rmteo on Sun Apr 24 15:28:19 MST 2011
I wonder if using FIOSET and FIOCLR might be faster. As a comparison I ran a test on an STM32F100 with a 24MHz clock and the following code:

  while (1) {
    GPIOC->BSRR = 1 <<8;
    GPIOC->BRR  = 1 <<8;
  }

BSRR is equivalent to FIOSET - writing a 1 sets the corresponding output pin. BRR resets the output pin - equivalent to FIOCLR. The code disassembles to:

         while (1) {
         GPIOC->BSRR = 1 <<8;
08000344 F2410300    movw r3, #0x1000
08000348 F2C40301    movt r3, #0x4001
0800034C F44F7280    mov.w r2, #0x100
08000350 611A        str r2, [r3, #16]    ; 1 cycle
--- main.c -- 92 -------------------------------------------
         GPIOC->BRR  = 1 <<8;
08000352 615A        str r2, [r3, #20]    ; 1 cycle
08000354 E7FC        b 0x08000350         ; 2 cycles
08000356 BF00        nop
08000358 0010        movs r0, r2
0800035A 2000        movs r0, #0

The pin toggling part takes a total of 4 cycles - 1 each for the pin ON/OFF and 2 for the branch. I observed 6MHz on the scope. With 72MHz clock you should see 18MHz - unless flash wait states come into play.

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:50 GMT

Content originally posted in LPCWare by ktownsend on Sun Apr 24 15:33:24 MST 2011
Have a look at section 8.5.1 of the LPC1343 UM for fast read/write to GPIO without having to worry about affecting other pins. You'll need to change the code below since it's from a system header file I wrote pre-CMSIS, but this shows how to use this feature for a single pin:

 #define ILI9328_WR_PIN 10
#define ILI9328_GPIO1DATA_WR (*(pREG32 (GPIO_GPIO1_BASE + ((1 << ILI9328_WR_PIN) << 2))))

then you can just do the following, which will change the pin in one operation without affecting all the others (meaning you don't have to waste time masking values yourself, etc.):

ILI9328_GPIO1DATA_WR = (0); // Clear pin
ILI9328_GPIO1DATA_WR = (1 << ILI9328_WR_PIN); // Set pin

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:51 GMT

Content originally posted in LPCWare by rmteo on Sun Apr 24 15:39:32 MST 2011
Sorry, it looks like the LPC13xx does not have FIOSET and FIOCLR registers - only the LPC17xx.

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:51 GMT

Content originally posted in LPCWare by ktownsend on Sun Apr 24 15:41:26 MST 2011

Quote: rmteo
Sorry, it looks like the LPC13xx does not have FIOSET and FIOCLR registers - only the LPC17xx.

See post below ... it has something similar, just not FIOSET and FIOCLR, but you can set and clear multiple pins in one operation without affecting the others. The UM might be a bit opaque about it, but once you wrap your head around it it's easy and works well.

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:52 GMT

Content originally posted in LPCWare by Ex-Zero on Sun Apr 24 15:48:05 MST 2011

Quote: rmteo
The pin toggling part takes a total of 4 cycles - 1 each for the pin ON/OFF and 2 for the branch.

Nearly correct:

str : 1 cycle
[COLOR=Red]taken[/COLOR] branch: 2 cycles

So the minimum in a simple loop is 18MHz.

If you just toggle without branch you'll see 36MHz :)

Quote:

However still not happy with only [B][SIZE=2]6 MHz[/SIZE][/B] with a [B]72MHz[/B] processor my expectations are much higher!!

Still disappointed?

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:53 GMT

Content originally posted in LPCWare by dirtyBits on Sun Apr 24 15:52:15 MST 2011

Quote: rmteo
Sorry, it looks like the LPC13xx does not have FIOSET and FIOCLR registers - only the LPC17xx.

Yes...:(

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:53 GMT

Content originally posted in LPCWare by dirtyBits on Sun Apr 24 15:55:28 MST 2011

Quote: Zero
Nearly correct:

str : 1 cycle
[COLOR=Red]taken[/COLOR] branch: 2 cycles

So the minimum in a simple loop is 18MHz.

If you just toggle without branch you'll see 36MHz :)

Still disappointed?

That would be awesome!
But code plz..because I lost you in between..

BTWay I checked the MCU setting and its already on optimization -O2.

Re: GPIO Speed

lpcware — Wed, 15 Jun 2016 21:49:54 GMT

Content originally posted in LPCWare by Ex-Zero on Sun Apr 24 16:04:23 MST 2011
Masterpiece of programming:

     while(1)
     {
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
          LED_ON;
          LED_OFF;
     }

In Disassembly view you can see what the compiler does:

          LED_ON;
0x00000280 <main+184>: str   r2, [r3, #0]
          LED_OFF;
0x00000282 <main+186>: str   r1, [r3, #0]
          LED_ON;
0x00000284 <main+188>: str   r2, [r3, #0]
          LED_OFF;
0x00000286 <main+190>: str   r1, [r3, #0]
          LED_ON;
0x00000288 <main+192>: str   r2, [r3, #0]