bcm2835  1.37
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Functions
GPIO register access

Functions

void bcm2835_gpio_fsel (uint8_t pin, uint8_t mode)
 
void bcm2835_gpio_set (uint8_t pin)
 
void bcm2835_gpio_clr (uint8_t pin)
 
void bcm2835_gpio_set_multi (uint32_t mask)
 
void bcm2835_gpio_clr_multi (uint32_t mask)
 
uint8_t bcm2835_gpio_lev (uint8_t pin)
 
uint8_t bcm2835_gpio_eds (uint8_t pin)
 
void bcm2835_gpio_set_eds (uint8_t pin)
 
void bcm2835_gpio_ren (uint8_t pin)
 
void bcm2835_gpio_clr_ren (uint8_t pin)
 
void bcm2835_gpio_fen (uint8_t pin)
 
void bcm2835_gpio_clr_fen (uint8_t pin)
 
void bcm2835_gpio_hen (uint8_t pin)
 
void bcm2835_gpio_clr_hen (uint8_t pin)
 
void bcm2835_gpio_len (uint8_t pin)
 
void bcm2835_gpio_clr_len (uint8_t pin)
 
void bcm2835_gpio_aren (uint8_t pin)
 
void bcm2835_gpio_clr_aren (uint8_t pin)
 
void bcm2835_gpio_afen (uint8_t pin)
 
void bcm2835_gpio_clr_afen (uint8_t pin)
 
void bcm2835_gpio_pud (uint8_t pud)
 
void bcm2835_gpio_pudclk (uint8_t pin, uint8_t on)
 
uint32_t bcm2835_gpio_pad (uint8_t group)
 
void bcm2835_gpio_set_pad (uint8_t group, uint32_t control)
 
void bcm2835_delay (unsigned int millis)
 
void bcm2835_delayMicroseconds (uint64_t micros)
 
void bcm2835_gpio_write (uint8_t pin, uint8_t on)
 
void bcm2835_gpio_write_multi (uint32_t mask, uint8_t on)
 
void bcm2835_gpio_write_mask (uint32_t value, uint32_t mask)
 
void bcm2835_gpio_set_pud (uint8_t pin, uint8_t pud)
 

Detailed Description

These functions allow you to control the GPIO interface. You can set the function of each GPIO pin, read the input state and set the output state.

Function Documentation

void bcm2835_delay ( unsigned int  millis)

Delays for the specified number of milliseconds. Uses nanosleep(), and therefore does not use CPU until the time is up. However, you are at the mercy of nanosleep(). From the manual for nanosleep(): If the interval specified in req is not an exact multiple of the granularity underlying clock (see time(7)), then the interval will be rounded up to the next multiple. Furthermore, after the sleep completes, there may still be a delay before the CPU becomes free to once again execute the calling thread.

Parameters
[in]millisDelay in milliseconds
void bcm2835_delayMicroseconds ( uint64_t  micros)

Delays for the specified number of microseconds. Uses a combination of nanosleep() and a busy wait loop on the BCM2835 system timers, However, you are at the mercy of nanosleep(). From the manual for nanosleep(): If the interval specified in req is not an exact multiple of the granularity underlying clock (see time(7)), then the interval will be rounded up to the next multiple. Furthermore, after the sleep completes, there may still be a delay before the CPU becomes free to once again execute the calling thread. For times less than about 450 microseconds, uses a busy wait on the System Timer. It is reported that a delay of 0 microseconds on RaspberryPi will in fact result in a delay of about 80 microseconds. Your mileage may vary.

Parameters
[in]microsDelay in microseconds
void bcm2835_gpio_afen ( uint8_t  pin)

Enable Asynchronous Falling Edge Detect Enable for the specified pin. When a falling edge is detected, sets the appropriate pin in Event Detect Status. Asynchronous means the incoming signal is not sampled by the system clock. As such falling edges of very short duration can be detected.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
void bcm2835_gpio_aren ( uint8_t  pin)

Enable Asynchronous Rising Edge Detect Enable for the specified pin. When a rising edge is detected, sets the appropriate pin in Event Detect Status. Asynchronous means the incoming signal is not sampled by the system clock. As such rising edges of very short duration can be detected.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
void bcm2835_gpio_clr ( uint8_t  pin)

Sets the specified pin output to LOW.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
See Also
bcm2835_gpio_write()
void bcm2835_gpio_clr_afen ( uint8_t  pin)

Disable Asynchronous Falling Edge Detect Enable for the specified pin.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
void bcm2835_gpio_clr_aren ( uint8_t  pin)

Disable Asynchronous Rising Edge Detect Enable for the specified pin.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
void bcm2835_gpio_clr_fen ( uint8_t  pin)

Disable Falling Edge Detect Enable for the specified pin.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
void bcm2835_gpio_clr_hen ( uint8_t  pin)

Disable High Detect Enable for the specified pin.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
void bcm2835_gpio_clr_len ( uint8_t  pin)

Disable Low Detect Enable for the specified pin.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
void bcm2835_gpio_clr_multi ( uint32_t  mask)

Sets any of the first 32 GPIO output pins specified in the mask to LOW.

Parameters
[in]maskMask of pins to affect. Use eg: (1 << RPI_GPIO_P1_03) | (1 << RPI_GPIO_P1_05)
See Also
bcm2835_gpio_write_multi()
void bcm2835_gpio_clr_ren ( uint8_t  pin)

Disable Rising Edge Detect Enable for the specified pin.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
uint8_t bcm2835_gpio_eds ( uint8_t  pin)

Event Detect Status. Tests whether the specified pin has detected a level or edge as requested by bcm2835_gpio_ren(), bcm2835_gpio_fen(), bcm2835_gpio_hen(), bcm2835_gpio_len(), bcm2835_gpio_aren(), bcm2835_gpio_afen(). Clear the flag for a given pin by calling bcm2835_gpio_set_eds(pin);

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
Returns
HIGH if the event detect status for the given pin is true.
void bcm2835_gpio_fen ( uint8_t  pin)

Enable Falling Edge Detect Enable for the specified pin. When a falling edge is detected, sets the appropriate pin in Event Detect Status. The GPRENn registers use synchronous edge detection. This means the input signal is sampled using the system clock and then it is looking for a ?100? pattern on the sampled signal. This has the effect of suppressing glitches.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
void bcm2835_gpio_fsel ( uint8_t  pin,
uint8_t  mode 
)

Sets the Function Select register for the given pin, which configures the pin as Input, Output or one of the 6 alternate functions.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
[in]modeMode to set the pin to, one of BCM2835_GPIO_FSEL_* from bcm2835FunctionSelect
void bcm2835_gpio_hen ( uint8_t  pin)

Enable High Detect Enable for the specified pin. When a HIGH level is detected on the pin, sets the appropriate pin in Event Detect Status.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
void bcm2835_gpio_len ( uint8_t  pin)

Enable Low Detect Enable for the specified pin. When a LOW level is detected on the pin, sets the appropriate pin in Event Detect Status.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
uint8_t bcm2835_gpio_lev ( uint8_t  pin)

Reads the current level on the specified pin and returns either HIGH or LOW. Works whether or not the pin is an input or an output.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
Returns
the current level either HIGH or LOW
uint32_t bcm2835_gpio_pad ( uint8_t  group)

Reads and returns the Pad Control for the given GPIO group.

Parameters
[in]groupThe GPIO pad group number, one of BCM2835_PAD_GROUP_GPIO_*
Returns
Mask of bits from BCM2835_PAD_* from bcm2835PadGroup
void bcm2835_gpio_pud ( uint8_t  pud)

Sets the Pull-up/down register for the given pin. This is used with bcm2835_gpio_pudclk() to set the Pull-up/down resistor for the given pin. However, it is usually more convenient to use bcm2835_gpio_set_pud().

Parameters
[in]pudThe desired Pull-up/down mode. One of BCM2835_GPIO_PUD_* from bcm2835PUDControl
See Also
bcm2835_gpio_set_pud()
void bcm2835_gpio_pudclk ( uint8_t  pin,
uint8_t  on 
)

Clocks the Pull-up/down value set earlier by bcm2835_gpio_pud() into the pin.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
[in]onHIGH to clock the value from bcm2835_gpio_pud() into the pin. LOW to remove the clock.
See Also
bcm2835_gpio_set_pud()
void bcm2835_gpio_ren ( uint8_t  pin)

Enable Rising Edge Detect Enable for the specified pin. When a rising edge is detected, sets the appropriate pin in Event Detect Status. The GPRENn registers use synchronous edge detection. This means the input signal is sampled using the system clock and then it is looking for a ?011? pattern on the sampled signal. This has the effect of suppressing glitches.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
void bcm2835_gpio_set ( uint8_t  pin)

Sets the specified pin output to HIGH.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
See Also
bcm2835_gpio_write()
void bcm2835_gpio_set_eds ( uint8_t  pin)

Sets the Event Detect Status register for a given pin to 1, which has the effect of clearing the flag. Use this afer seeing an Event Detect Status on the pin.

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
void bcm2835_gpio_set_multi ( uint32_t  mask)

Sets any of the first 32 GPIO output pins specified in the mask to HIGH.

Parameters
[in]maskMask of pins to affect. Use eg: (1 << RPI_GPIO_P1_03) | (1 << RPI_GPIO_P1_05)
See Also
bcm2835_gpio_write_multi()
void bcm2835_gpio_set_pad ( uint8_t  group,
uint32_t  control 
)

Sets the Pad Control for the given GPIO group.

Parameters
[in]groupThe GPIO pad group number, one of BCM2835_PAD_GROUP_GPIO_*
[in]controlMask of bits from BCM2835_PAD_* from bcm2835PadGroup. Note that it is not necessary to include BCM2835_PAD_PASSWRD in the mask as this is automatically included.
void bcm2835_gpio_set_pud ( uint8_t  pin,
uint8_t  pud 
)

Sets the Pull-up/down mode for the specified pin. This is more convenient than clocking the mode in with bcm2835_gpio_pud() and bcm2835_gpio_pudclk().

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
[in]pudThe desired Pull-up/down mode. One of BCM2835_GPIO_PUD_* from bcm2835PUDControl
void bcm2835_gpio_write ( uint8_t  pin,
uint8_t  on 
)

Sets the output state of the specified pin

Parameters
[in]pinGPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
[in]onHIGH sets the output to HIGH and LOW to LOW.
void bcm2835_gpio_write_mask ( uint32_t  value,
uint32_t  mask 
)

Sets the first 32 GPIO output pins specified in the mask to the value given by value

Parameters
[in]valuevalues required for each bit masked in by mask, eg: (1 << RPI_GPIO_P1_03) | (1 << RPI_GPIO_P1_05)
[in]maskMask of pins to affect. Use eg: (1 << RPI_GPIO_P1_03) | (1 << RPI_GPIO_P1_05)
void bcm2835_gpio_write_multi ( uint32_t  mask,
uint8_t  on 
)

Sets any of the first 32 GPIO output pins specified in the mask to the state given by on

Parameters
[in]maskMask of pins to affect. Use eg: (1 << RPI_GPIO_P1_03) | (1 << RPI_GPIO_P1_05)
[in]onHIGH sets the output to HIGH and LOW to LOW.