raspberry GPIO 寄存器访问函数简介

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)

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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.

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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]

millis

Delay 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]

micros

Delay 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]

pin

GPIO 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]

pin

GPIO 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]

pin

GPIO 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]

pin

GPIO 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]

pin

GPIO 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]

pin

GPIO 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]

pin

GPIO 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]

pin

GPIO 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]

mask

Mask 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]

pin

GPIO 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]

pin

GPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.

Returns:

HIGH if the event detect status for th 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]

pin

GPIO 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]	pin	GPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
[in]	mode	Mode 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]

pin

GPIO 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]

pin

GPIO 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]

pin

GPIO 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]

group

The 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]

pud

The 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]	pin	GPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
[in]	on	HIGH 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]

pin

GPIO 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]

pin

GPIO 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]

pin

GPIO 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]

mask

Mask 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]	group	The GPIO pad group number, one of BCM2835_PAD_GROUP_GPIO_*
[in]	control	Mask of bits from BCM2835_PAD_* from bcm2835PadGroup

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]	pin	GPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
[in]	pud	The 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]	pin	GPIO number, or one of RPI_GPIO_P1_* from RPiGPIOPin.
[in]	on	HIGH 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]	value	values required for each bit masked in by mask, eg: (1 << RPI_GPIO_P1_03) | (1 << RPI_GPIO_P1_05)
[in]	mask	Mask 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]	mask	Mask of pins to affect. Use eg: (1 << RPI_GPIO_P1_03) | (1 << RPI_GPIO_P1_05)
[in]	on	HIGH sets the output to HIGH and LOW to LOW.