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- #ifndef ROWSCANNER_SPI_SHIFTREGISTERS_H
- #define ROWSCANNER_SPI_SHIFTREGISTERS_H
- #include <Arduino.h>
- #include <inttypes.h>
- #include <SPI.h>
- #include <RowScannerInterface.h>
- #include <RowPort.h>
- #include <ColPort.h>
-
- /* RowScanner_SPIShiftRegisters reads shift registers.
- shift registers 74HC165 Parallel-In-Serial-Out (PISO)
-
- in sketch:
- const uint8_t RowScanner_SPIShiftRegisters::SHIFT_LOAD = 10;
- call begin() from setup()
-
- Upto 4 shift registers can be in a daisy chained.
- The maximum keys per row is 31, because Arduino's largest type is 32 bits and rowEnd consumes the last bit.
-
- The shift registers are active high:
- 10k pull-down resistors are grounded
- connect controller's MISO pin to shift register's QH pin
-
- */
- class RowScanner_SPIShiftRegisters : public RowScannerInterface
- {
- private:
- static const uint8_t SHIFT_LOAD; //controller's pin number that is connected to shift register's SHIFT_LOAD pin
- const uint8_t STROBE_PIN; //Arduino pin number connected to this row
- const read_pins_mask_t ROW_END; //bitwise, 1 bit marks positioned after last key of row
- const uint8_t BYTE_COUNT; //number of bytes to read from shift registers
- public:
- RowScanner_SPIShiftRegisters(const uint8_t STROBE_PIN, uint8_t KEY_COUNT);
- virtual read_pins_t scan(read_pins_mask_t& rowEnd);
- void begin();
- };
- #endif
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