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- #ifndef ROWSCANNER_SHIFTREGSPISOSINGLEROW_H
- #define ROWSCANNER_SHIFTREGSPISOSINGLEROW_H
-
- #include <Arduino.h>
- #include <inttypes.h>
- #include <config_keybrd.h>
- #include <SPI.h>
- #include <ScannerInterface.h>
-
- /* Scanner_ShiftRegsPISOSingleRow reads shift registers.
- This was tested on 74HC165 shift registers, which are Parallel-In-Serial-Out (PISO).
- Upto 4 shift registers can be in a daisy chained for a total of 32 read pins.
-
- Example instantiation:
- Row row_R0(scanner_R, 0, ptrsKeys_R0, sizeof(ptrsKeys_R0)/sizeof(*ptrsKeys_R0));
- Scanner_ShiftRegsPISOSingleRow scanner_R(HIGH, SS, 4);
-
- The Row "strobePin" parameter is ignored.
- In the above example, the "strobePin" argument is 0, but it doesn't matter what value is given.
-
- There are three Scanner_ShiftRegsPISOSingleRow parameters.
- "strobeOn" paramter is ignored, but should be active state HIGH or LOW required by ScannerInterface.
-
- "slaveSelect" paramter can be any controller pin connected to shift register's SHIFT-LOAD pin.
- slaveSelect pin SS (Arduino pin 10) has the fastest scan.
-
- "byte_count" is the number of bytes to read from shift registers (1 to 4).
- byte_count should cover all the row's keys:
- byte_count*8 >= row's keyCount
-
- Hardware setup:
- There is only one row, and it is permanently active.
- Switches are connected to shift-register parallel-input pins (diodes are not needed) and row.
-
- For active low:
- Shift-register parallel-input pins need 10k Ohm pull-up resistors powered.
- Switches connect powered row to parallel-input pins.
- Controller's MISO pin is connected to shift register's complementary serial output (/QH) pin
-
- For active high:
- Shift-register parallel-input pins need 10k pull-down resistors grounded.
- Switches connect grouned row to parallel-input pins.
- Controller's MISO pin is connected to shift register's serial output (QH) pin
- */
- class Scanner_ShiftRegsPISOSingleRow : public ScannerInterface
- {
- private:
- const uint8_t slaveSelect; //controller's pin number that is
- // connected to shift register's SHIFT-LOAD pin
- const uint8_t byte_count; //number of bytes to read from shift registers
- public:
- Scanner_ShiftRegsPISOSingleRow(const bool strobeOn,
- const uint8_t slaveSelect, const uint8_t byte_count);
- void init(const uint8_t strobePin);
- void begin();
- virtual read_pins_t scan(const uint8_t strobePin);
- };
- #endif
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