31 рядки
1.2 KiB
C++
31 рядки
1.2 KiB
C++
#ifndef PORT_MCP23018_H
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#define PORT_MCP23018_H
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#include "Port_MCP23017.h"
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/*
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write pins are connected to matrix Row (strobe pin) or LED.
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readPins are connected to matrix column to read which keys are pressed.
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Port_MCP23018 can only be active low (Scanner_IOE::activeState = LOW).
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Open-drain active high would not work because pull down resistors have no effect on sink.
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https://en.wikipedia.org/wiki/Open_collector
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Use LED_PortOpenDrain class for indicator LEDs.
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Example instantiation:
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const uint8_t IOE_ADDR = 0x20; //MCP23018 address pin grounded
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Port_MCP23018 portB(IOE_ADDR, 1, 0); //all pins are set to output for strobes and LEDs
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Port_MCP23018 portA(IOE_ADDR, 0, 1<<0 | 1<<1 ); //pin 0 and pin 1 are set to input for reading,
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//remaining pins can be used for LEDs
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Diode orientation
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----------------
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Diode orientation is explained in keybrd_library_user_guide.md > Diode orientation
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*/
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class Port_MCP23018 : public Port_MCP23017
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{
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public:
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Port_MCP23018(const uint8_t deviceAddr, const uint8_t portNum, const uint8_t readPins)
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: Port_MCP23017(deviceAddr, portNum, readPins) {}
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};
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#endif
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