2011-09-22 04:18:42     Gpio_get_value in 526

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2011-09-22 04:18:42     Gpio_get_value in 526

Ganesh krish (INDIA)

Message: 103496   


Hi world,


    When i enable PF6 as an interrupt , but in ISR i need to read the status of tht gpio pin for tht im using gpio_get_value(GPIO_PF6) .... I do get the interrupt when PF6 goes high to low , i set the interrupt as FALLING ,,, then when i read the status of PF6 , i get the value as 1 when its physically 0 and 0 when its value is physically 1 ,,,, i do get the opposite value of tht pin ..HELP !!!!




2011-09-23 01:26:28     Re: Gpio_get_value in 526

Sonic Zhang (CHINA)

Message: 103506   


What polarity of the PIN do you set?




2011-09-23 14:03:07     Re: Gpio_get_value in 526


Message: 103517   




The polarity of the inputs can be switched by writting a 0 or 1 to the "/sys/class/gpio/gpio{pin}/active_low" file.  A 1 means that a 0 value will be read from the value file as a 1 and visa-versa.  A 0 means that the values will be their true states 0 is 0 and 1 is 1.


Be sure to look carefully at your schematics:  because it may actually be reversed in hardware also.