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#include "mbed.h"
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/** MCP23008 class
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*
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* Allow access to an I2C connected MCP23008 8-bit I/O extender chip
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*
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*/
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class MCP23008 {
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public:
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enum Frequency {
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Frequency_100KHz = 100000,
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Frequency_400KHz = 400000,
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/* Note: 1.7MHz probably won't work for mbed */
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Frequency_1700KHz = 1700000
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};
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enum Pin {
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Pin_GP0 = 0x01,
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Pin_GP1 = 0x02,
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Pin_GP2 = 0x04,
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Pin_GP3 = 0x08,
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Pin_GP4 = 0x10,
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Pin_GP5 = 0x20,
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Pin_GP6 = 0x40,
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Pin_GP7 = 0x80,
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Pin_All = 0xFF
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};
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/** Constructor
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*
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* @param sda I2C sda pin
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* @param scl I2C scl pin
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* @param address The hardware address of the MCP23008. This is the 3-bit
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* value that is physically set via A0, A1, and A2.
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* @param freq The I2C frequency. Should probably be 100KHz or 400KHz.
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*/
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MCP23008 ( PinName sda, PinName scl, uint8_t address, Frequency freq = Frequency_100KHz );
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/** Set pins to input mode
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*
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* This function is used to set which pins are inputs (if any). Example:
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* set_inputs ( Pin_GP0 | Pin_GP1 | Pin_GP2 );
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* Note that these are set to input in addition to the previously set.
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* In other words, the following:
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* set_inputs ( Pin_GP1 );
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* set_inputs ( Pin_GP2 );
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* Results in at least two pins set to input.
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*
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* @param pins A bitmask of pins to set to input mode.
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*/
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void set_input_pins ( uint8_t pins );
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/** Set pins to output mode
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*
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* This function is used to set which pins are outputs (if any). Example:
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* set_outputs ( Pin_GP0 | Pin_GP1 | Pin_GP2 );
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* Note that these are set to output in addition to the previously set.
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* In other words, the following:
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* set_outputs ( Pin_GP1 );
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* set_outputs ( Pin_GP2 );
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* Results in at least two pins set to output.
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*
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* @param pins A bitmask of pins to set to output mode.
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*/
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void set_output_pins ( uint8_t pins );
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/** Write to the output pins.
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*
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* This function is used to set output pins on or off.
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*
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* @param values A bitmask indicating whether a pin should be on or off.
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*/
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void write_outputs ( uint8_t values );
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/** Read back the outputs.
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*
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* This function is used to read the last values written to the output pins.
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*
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* @returns The value from the OLAT register.
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*/
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uint8_t read_outputs ();
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/** Read from the input pins.
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*
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* This function is used to read the values from the input pins.
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*
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* @returns A bitmask of the current state of the input pins.
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*/
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uint8_t read_inputs ();
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/** Set the input pin polarity.
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*
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* This function sets the polarity of the input pins.
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* A 1 bit is inverted polarity, a 0 is normal.
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*
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* @param values A bitmask of the input polarity.
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*/
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void set_input_polarity ( uint8_t values );
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/** Read back the current input pin polarity.
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*
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* This function reads the current state of the input pin polarity.
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*
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* @returns The value from the IPOL register.
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*/
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uint8_t get_input_polarity ();
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/** Enable and disable the internal pull-up resistors for input pins.
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*
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* This function enables the internal 100 kΩ pull-up resistors.
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* A 1 bit enables the pull-up resistor for the corresponding input pin.
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*
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* @param values A bitmask indicating which pull-up resistors should be enabled/disabled.
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*/
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void set_pullups ( uint8_t values );
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/** Get the current state of the internal pull-up resistors.
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*
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* @returns The current state of the pull-up resistors.
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*/
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uint8_t get_pullups ();
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/** Generate an interrupt when a pin changes.
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*
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* This function enables interrupt generation for the specified pins.
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* The interrupt is active-low by default.
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* The function acknowledge_interrupt must be called before another
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* interrupt will be generated.
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* Example:
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* @code
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* InterruptIn in ( p16 );
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* MCP23008 mcp ( p9, p10, 0 );
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* in.fall ( &interrupt );
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* mcp.interrupt_on_changes ( MCP23008::Pin_GP0 );
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* while ( 1 ) {
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* wait ( 1 );
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* }
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* @endcode
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*
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* @param pins A bitmask of the pins that may generate an interrupt.
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*/
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void interrupt_on_changes ( uint8_t pins );
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/** Disables interrupts for the specified pins.
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*
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* @param values A bitmask indicating which interrupts should be disabled.
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*/
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void disable_interrupts ( uint8_t pins );
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/** Acknowledge a generated interrupt.
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*
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* This function must be called when an interrupt is generated to discover
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* which pin caused the interrupt and to enable future interrupts.
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*
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* @param pin An output paramter that specifies which pin generated the interrupt.
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* @param values The current state of the input pins.
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*/
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void acknowledge_interrupt ( uint8_t &pin, uint8_t &values );
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private:
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uint8_t read_register ( uint8_t reg );
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void write_register ( uint8_t reg, uint8_t value );
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void write_mask ( uint8_t reg, uint8_t mask, bool value );
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void reset ();
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I2C i2c;
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uint8_t i2c_address;
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};
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