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107 lines
3.7 KiB
Markdown
107 lines
3.7 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/ShiftInSlow/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/ShiftInSlow/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/ShiftInSlow/issues)
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[](https://github.com/RobTillaart/ShiftInSlow/blob/master/LICENSE)
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[](https://github.com/RobTillaart/ShiftInSlow/releases)
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[](https://registry.platformio.org/libraries/robtillaart/ShiftInSlow)
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# ShiftInSlow
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Arduino library for shiftIn with build-in delay - e.g. for 74HC165.
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## Description
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shiftInSlow 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 dataPin and clockPin are set in the constructor, the delay is configurable per byte send to be able to optimize runtime.
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#### Related
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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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## Performance
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The performance of **read()** with a delay of 0 microseconds is slower than the default Arduino
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**shiftIn()** due to some overhead.
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The delay requested is split in two (expect rounding errors) to have "nice" looking pulse
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with the duty cycle around 50%.
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Performance measurements are meaningless, as the purpose of this library is to
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slow the pulse train to a working level.
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## Interface
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```cpp
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#include "ShiftInSlow.h"
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```
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#### Functions
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The interface exists of the following functions:
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- **ShiftInSlow(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder = LSBFIRST)** constructor,
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bit order is default set to LSBFIRST.
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- **int read()** reads a new value.
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- **int lastRead()** returns last value read.
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- **void setDelay(uint16_t microseconds = 0)** set delay per bit from 0 .. 65535 microseconds.
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Note that the delay is split in two parts to keep the duty cycle around 50%.
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- **uint16_t getDelay()** returns the set delay in microseconds.
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- **bool setBitOrder(uint8_t bitOrder = LSBFIRST)** set LSBFIRST or MSBFIRST. Returns false for other values.
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- **uint8_t getBitOrder(void)** returns LSBFIRST or MSBFIRST.
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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 a select pin to be more SPI alike?
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- would allow SPI debugging?
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- increase max delay uint32_t ?
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- would allow pulses in "second" domain.
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#### Could
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- add examples
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- adaptive speed example?
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#### Wont
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- delay/2 is not exact half when delay is odd.
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- no big issue.
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- del_before and del_after could prepare for duty cycle.
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- get set dutyCycle(0 .. 99%)
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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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- read16/24/32 to read more bytes is a user task.
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## Support
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If you appreciate my libraries, you can support the development and maintenance.
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Improve the quality of the libraries by providing issues and Pull Requests, or
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donate through PayPal or GitHub sponsors.
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Thank you,
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