38 行
1.4 KiB
C++
38 行
1.4 KiB
C++
#include "PortWrite_MCP23S17.h"
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/* begin() is called from Scanner_IOE::begin().
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Initiates SPI bus and configures port pins to output.
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MCP23S17 SPI interface is 10 MHz max.
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The electrical limitation to bus speed is bus capacitance and the length of the wires involved.
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Longer wires require lower clock speeds.
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*/
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void PortWrite_MCP23S17::begin()
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{
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pinMode(SS, OUTPUT); //configure controller's Slave Select pin to output
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digitalWrite(SS, HIGH); //disable Slave Select
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SPI.begin();
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SPI.beginTransaction(SPISettings (5000000, MSBFIRST, SPI_MODE0)); //control SPI bus, 5 MHz
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//SPI.endTransaction() not called to release SPI bus because keyboard only has one SPI device.
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transfer(port.DEVICE_ADDR << 1, port.num, 0); //configure port direction (port.num) to output (0)
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}
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/* write() sets pin output to logicLevel.
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pin is bit pattern, where pin being set is 1.
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logicLevel is HIGH or LOW.
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write() does not overwrite the other pins.
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*/
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void PortWrite_MCP23S17::write(const uint8_t pin, const bool logicLevel)
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{
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if (logicLevel == LOW)
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{
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port.outputVal &= ~pin; //set pin output to low
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}
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else
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{
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port.outputVal |= pin; //set pin output to high
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}
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transfer(port.DEVICE_ADDR << 1, port.num + 0x12, port.outputVal); //set GPIO port to outputVal
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}
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