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Added some clarifications to comments in esp/gpio.h

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This commit is contained in:
Alex Stewart 2016-02-22 09:32:12 -08:00
parent c36feab845
commit 8279b5cfd1
1 changed files with 28 additions and 6 deletions
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32
core/include/esp/gpio.h
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@ -29,6 +29,9 @@ void gpio_enable(const uint8_t gpio_num, const gpio_direction_t direction);
* 100K ohms (see http://bbs.espressif.com/viewtopic.php?t=1079#p4097)
* However, measured values suggest that the actual value is likely to be close
* to 47K in reality.
*
* NOTE: The enabled_during_sleep setting is currently untested (please send
* feedback if you give it a try)
*/
void gpio_set_pullup(uint8_t gpio_num, bool enabled, bool enabled_during_sleep);
@ -46,6 +49,9 @@ static inline void gpio_disable(const uint8_t gpio_num)
/* Set whether the specified pin continues to drive its output when the ESP8266
* goes into sleep mode. Note that this setting is reset to off whenever
* gpio_enable is called, so this must be called after calling that function.
*
* NOTE: This functionality is currently untested (please send feedback if you
* give it a try)
*/
static inline void gpio_set_output_on_sleep(const uint8_t gpio_num, bool enabled)
{
@ -58,7 +64,15 @@ static inline void gpio_set_output_on_sleep(const uint8_t gpio_num, bool enabled
/* Set output of a pin high or low.
*
* Only works if pin has been set to GPIO_OUTPUT via gpio_enable()
* Only works if pin has been set to GPIO_OUTPUT or GPIO_OUT_OPEN_DRAIN via
* gpio_enable()
*
* If the mode is GPIO_OUT_OPEN_DRAIN, setting it low (false) will pull the pin
* down to ground, but setting it high (true) will allow it to float. Note
* that even in GPIO_OUT_OPEN_DRAIN mode, the input gates are still physically
* connected to the pin, and can be damaged if the voltage is not in either the
* "low" or "high" range. Make sure there is some sort of pull-up resistor on
* the line to avoid floating logic lines!
*/
static inline void gpio_write(const uint8_t gpio_num, const bool set)
{
@ -70,7 +84,10 @@ static inline void gpio_write(const uint8_t gpio_num, const bool set)
/* Toggle output of a pin
*
* Only works if pin has been set to GPIO_OUTPUT via gpio_enable()
* Only works if pin has been set to GPIO_OUTPUT or GPIO_OUT_OPEN_DRAIN via
* gpio_enable()
*
* See notes in gpio_write() about GPIO_OUT_OPEN_DRAIN mode.
*/
static inline void gpio_toggle(const uint8_t gpio_num)
{
@ -88,8 +105,12 @@ static inline void gpio_toggle(const uint8_t gpio_num)
/* Read input value of a GPIO pin.
*
* If pin is set as an input, this reads the value on the pin.
* If pin is set as an output, this reads the last value written to the pin.
* If pin is set GPIO_INPUT, this reads the level on the pin.
* If pin is set GPIO_OUTPUT, this reads the level at which the pin is
* currently being driven (i.e. the last value written).
* If pin is set GPIO_OUT_OPEN_DRAIN, when the pin is written low, this will
* return low (false), when the pin is written high, this will behave like
* GPIO_INPUT.
*/
static inline bool gpio_read(const uint8_t gpio_num)
{
@ -100,7 +121,8 @@ extern void gpio_interrupt_handler(void);
/* Set the interrupt type for a given pin
*
* If int_type is not GPIO_INTTYPE_NONE, the gpio_interrupt_handler will be attached and unmasked.
* If int_type is not GPIO_INTTYPE_NONE, the gpio_interrupt_handler will be
* attached and unmasked.
*/
static inline void gpio_set_interrupt(const uint8_t gpio_num, const gpio_inttype_t int_type)
{