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