[ECOS] AT91 GPIO read problem

[ECOS] AT91 GPIO read problem

[Steven Clugston]

I'm fairly new to AT91 and have been trying to use the platform macros to setup and read some GPIOs on an Olimex AT91SAM7S256 based board.

They provide their board pre-flashed with a demo program (no source) and you can press the micro switches to toggle/activate various board features using the program. The switches are externally pulled up.

With ecos, I can configure any gpio as an output and set it high or low without any problems, but when it comes to reading a pin's value it seems to always return 0 regardless of the logic level on it.

cyg_bool value
HAL_ARM_AT91_GPIO_CFG_DIRECTION(AT91_GPIO_PA29, AT91_PIN_IN);
HAL_ARM_AT91_GPIO_GET(AT91_GPIO_PA29, value);

'value' is always 0. I've tried a couple of different boards in case the first one has been damaged somehow and different pins in case there is a perculiarity with a particular mulifunction pin.

Also:
 cyg_uint32 pdsr;
 HAL_READ_UINT32(AT91_PIO + AT91_PIO_PDSR, pdsr);
The pdsr status register never seems to change its value when the external logic level is changed.
The only example I can find is in the AT91 usb driver on the power pin.

Does anybody familiar with the AT91 have any ideas what school boy type error I might be making?

Thanks,

Steven

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Re: [ECOS] AT91 GPIO read problem

[Andrew Lunn]

On Tue, Aug 18, 2009 at 03:36:53PM +0100, Steven Clugston wrote:
> I'm fairly new to AT91 and have been trying to use the platform macros to setup and read some GPIOs on an Olimex AT91SAM7S256 based board.
> 
> They provide their board pre-flashed with a demo program (no source) and you can press the micro switches to toggle/activate various board features using the program. The switches are externally pulled up.
> 
> With ecos, I can configure any gpio as an output and set it high or low without any problems, but when it comes to reading a pin's value it seems to always return 0 regardless of the logic level on it.
> 
> cyg_bool value
> HAL_ARM_AT91_GPIO_CFG_DIRECTION(AT91_GPIO_PA29, AT91_PIN_IN);
> HAL_ARM_AT91_GPIO_GET(AT91_GPIO_PA29, value);
> 
> 'value' is always 0. I've tried a couple of different boards in case the first one has been damaged somehow and different pins in case there is a perculiarity with a particular mulifunction pin.
> 
> Also:
>  cyg_uint32 pdsr;
>  HAL_READ_UINT32(AT91_PIO + AT91_PIO_PDSR, pdsr);
> The pdsr status register never seems to change its value when the external logic level is changed.
> The only example I can find is in the AT91 usb driver on the power pin.
> 
> Does anybody familiar with the AT91 have any ideas what school boy type error I might be making?

Did you enable the clock to the GPIO subsystem? Output works without a
clock, input does not. Look in i think the power management section of
the manual.

       Andrew

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RE: [ECOS] AT91 GPIO read problem

[Steven Clugston]

>> With ecos, I can configure any gpio as an output and set it high or low without any problems, but when it comes to reading a pin's value it seems to always return 0 regardless of the logic level on it.

>> cyg_bool value
>> HAL_ARM_AT91_GPIO_CFG_DIRECTION(AT91_GPIO_PA29, AT91_PIN_IN);
>> HAL_ARM_AT91_GPIO_GET(AT91_GPIO_PA29, value);

>> 'value' is always 0. I've tried a couple of different boards in case the first one has been damaged somehow and different pins in case there is a perculiarity with a particular mulifunction pin.
>> Does anybody familiar with the AT91 have any ideas what school boy type error I might be making?

> Did you enable the clock to the GPIO subsystem? Output works without a
> clock, input does not. Look in i think the power management section of
> the manual.

>       Andrew

No, I didn't even know there was a GPIO subsystem that needs a clock, but now I know that fixed it:

HAL_WRITE_UINT32 (AT91_PMC + AT91_PMC_PCER, AT91_PMC_PCER_PIOA);

Thanks Andrew, there is only brief mention of it in the 757 page AT91SAM7 manual, so it might have taken me awhile to chance upon it.

Regards,

Steven


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