/****************************************************************************** * The MIT License * * Copyright (c) 2010 Perry Hung. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. *****************************************************************************/ /** * @file io.h * * @brief Arduino-compatible digital pin I/O interface. */ #ifndef _IO_H #define _IO_H #include "gpio.h" #include "adc.h" #ifdef __cplusplus extern "C"{ #endif /** * Specifies a GPIO pin behavior. * * Each of the GPIO pins on a Maple board may be configured using * pinMode() to behave in a number of ways: as a digital output pin, * or as an analog input pin, etc., depending on the particular pin. * * This enum specifies the complete set of possible configurations; * not every pin can have all of these modes. For example, on the * Maple, pin 15 may be configured as INPUT_ANALOG, but not as PWM. * See your device's silkscreen and and the GPIO documentation for * more information. * * @see pinMode() */ typedef enum WiringPinMode { OUTPUT, /**< Basic digital output: when the pin is HIGH, the voltage is held at +3.3v (Vcc) and when it is LOW, it is pulled down to ground. */ OUTPUT_OPEN_DRAIN, /**< In open drain mode, the pin indicates "low" by accepting current flow to ground and "high" by providing increased impedance. An example use would be to connect a pin to a bus line (which is pulled up to a positive voltage by a separate supply through a large resistor). When the pin is high, not much current flows through to ground and the line stays at positive voltage; when the pin is low the bus "drains" to ground with a small amount of current constantly flowing through the large resistor from the external supply. In this mode no current is ever actually /sourced/ from the pin. */ INPUT, /**< Basic digital input. The pin voltage is sampled; when it is closer to 3.3v (Vcc) the pin status is high, and when it is closer to 0v (ground) it is low. If no external circuit is pulling the pin voltage to high or low, it will tend to randomly oscillate and be very sensitive to noise (e.g., a breath of air across the pin might cause the state to flip). */ INPUT_ANALOG, /**< This is a special mode for when the pin will be used for analog (not digital) reads. Enables ADC conversion to be performed on the voltage at the pin. */ INPUT_PULLUP, /**< The state of the pin in this mode is reported the same way as with INPUT, but the pin voltage is gently "pulled up" towards +3.3v. This means the state will be high unless an external device is specifically pulling the pin down to ground, in which case the "gentle" pull up will not affect the state of the input. */ INPUT_PULLDOWN, /**< The state of the pin in this mode is reported the same way as with INPUT, but the pin voltage is gently "pulled down" towards 0v. This means the state will be low unless an external device is specifically pulling the pin up to 3.3v, in which case the "gentle" pull down will not affect the state of the input. */ INPUT_FLOATING, /**< Synonym for INPUT. */ PWM, /**< This is a special mode for when the pin will be used for PWM output (a special case of digital output). */ PWM_OPEN_DRAIN, /**< Like PWM, except that instead of alternating cycles of LOW and HIGH, the voltage on the pin consists of alternating cycles of LOW and floating (disconnected). */ } WiringPinMode; /** * Configure behavior of a GPIO pin. * * @param pin Pin to configure. One of: 0-38 (pin numbers as labeled * on silkscreen), or D0-D38 (symbols for same) * @param mode Mode corresponding to desired pin behavior. * @see WiringPinMode */ void pinMode(uint8 pin, WiringPinMode mode); /** * Writes a (digital) value to a pin. The pin must have its * mode set to OUTPUT or OUTPUT_OPEN_DRAIN. * * @param pin Pin to write to. One of: 0-38 (pin numbers as labeled * on silkscreen), or D0-D38 (symbols for same) * @param value Either LOW (write a 0) or HIGH (write a 1). * @see pinMode() */ void digitalWrite(uint8 pin, uint8 value); /** * Read a digital value from a pin. The pin must have its mode set to * one of INPUT, INPUT_PULLUP, and INPUT_PULLDOWN. * * @param pin Pin to read from. One of: 0-38 (pin numbers as labeled * on silkscreen), or D0-D38 (symbols for same) * @return LOW or HIGH. * @see pinMode() */ uint32 digitalRead(uint8); /** * Read an analog value from pin. This function blocks during ADC * conversion, and has 12 bits of resolution. The pin must have its * mode set to INPUT_ANALOG. Ignoring function call overhead, * conversion time is 55.5 cycles. * * @param pin Pin to read from. One of: 0, 1, 2, 3, 10, 11, 12, 13, * 15, 16, 17, 18, 19, 20, 27, 28. * @return ADC-converted voltage, in the range 0--4095, inclusive * (i.e. a 12-bit ADC conversion). * @see pinMode() */ uint32 analogRead(uint8 pin); #ifdef __cplusplus } // extern "C" #endif #endif