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89 lines
3.4 KiB
Markdown
89 lines
3.4 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/ShiftOutSlow/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/ShiftOutSlow/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/ShiftOutSlow/blob/master/LICENSE)
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[](https://github.com/RobTillaart/ShiftOutSlow/releases)
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# ShiftOutSlow
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Arduino library for shiftOut with build-in delay - e.g. for 74HC595
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Related libraries
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- https://github.com/RobTillaart/FastShiftIn
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- https://github.com/RobTillaart/FastShiftOut
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- https://github.com/RobTillaart/FastShiftInOut
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- https://github.com/RobTillaart/ShiftInSlow
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- https://github.com/RobTillaart/ShiftOutSlow
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## Description
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ShiftOutSlow is an experimental library that has a build in delay (in microseconds) that allows tuning the time per bit.
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This allows one to improve reliability e.g. when using longer lines.
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The data pin and clock pin are set in the constructor, the delay can be set per byte send to be able to optimize runtime.
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ShiftOutSlow implements the print interface.
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## Performance
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The performance of **write()** with a delay of 0 microseconds is slower than the default Arduino
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**shiftOut()** due to some overhead.
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The delay requested is divided by two to minimize disruption of the duty cycle of the clock pulse,
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resulting in "better" pulses.
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## Interface
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The interface exists of the following functions:
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- **ShiftOutSlow(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder = LSBFIRST)** constructor.
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- **size_t write(uint8_t data)** writes a new value. Returns the bytes written.
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- **size_t write(const uint8_t \*buffer, size_t size)** writes an array of size over shift out. Uses **write(uint8_t)** so expect about equal performance. Returns the bytes written.
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- **uint8_t lastWritten()** returns last value written.
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- **void setDelay(uint16_t microSeconds)** set delay per bit from 0 .. 65535 microseconds.
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Note that the delay is not the time per bit but an additional time per bit.
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Note: the delay can be set runtime per write / print call.
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- **uint16_t getDelay()** returns the set delay in microseconds.
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- **bool setBitOrder(uint8_t bitOrder)** set LSBFIRST or MSBFIRST. Returns false for other values.
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Note: bit order can be changed runtime per write / print call.
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- **uint8_t getBitOrder(void)** returns LSBFIRST or MSBFIRST (typical 0 and 1).
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### Print interface
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As this library implements the print interface one can use:
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- **size_t print(any)** print any data type.
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- **size_t println(any)** print any data type followed by a newline "\n".
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## Operation
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See examples.
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## Future
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#### must
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- improve documentation
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#### should
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- add examples
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- adaptive speed example?
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#### could
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- Add a select pin to be more SPI alike?
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- increase max delay uint32_t ?
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- set delay in terms of frequency - delay is 'wave length'
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- set delay in terms of max total time the read may cost.
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- set default delay = 0, is no delay ?
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- get set dutyCycle(0 .. 99%)
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- optimize the place to yield() ?
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