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139 lines
4.6 KiB
Markdown
139 lines
4.6 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/map2bits/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/map2bits/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/map2bits/issues)
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[](https://github.com/RobTillaart/map2bits/blob/master/LICENSE)
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[](https://github.com/RobTillaart/map2bits/releases)
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[](https://registry.platformio.org/libraries/robtillaart/map2bits)
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# map2bits
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Arduino library for mapping a float to a number of bits.
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## Description
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Map2bits is an **experimental** library which can be used to map a float
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value to a number of HIGH bits in an 32 bits integer..
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The float value can be the result of a calculation or measurement from a
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sensor, e.g. temperature, humidity, light, distance, direction or pressure.
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**map2bits** is developed to drive a led bar like this one.
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https://www.tinytronics.nl/shop/nl/displays/segmenten/led-bar-10x-rood
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typical in combination with a PCF8575 or a MCP23017.
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These are used for displaying e.g. audio volume, current level, temperature
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etc in a visual way.
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Another application might be to control multiple pumps in a row to pump
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water from a pit.
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Depending on the level of the water more pumps need to be switched on.
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In short many devices to drive or applications to think of.
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As always, feedback is welcome.
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#### Related
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Other mapping libraries
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- https://github.com/RobTillaart/FastMap
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- https://github.com/RobTillaart/Gamma
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- https://github.com/RobTillaart/map2bits
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- https://github.com/RobTillaart/map2colour
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- https://github.com/RobTillaart/moduloMap
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- https://github.com/RobTillaart/MultiMap
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## Interface
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```cpp
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#include "map2bits.h"
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```
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#### Functions
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- **map2bits()** Constructor, defines a default mapping of (0..100 => 10)
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- **uint8_t init(float in_min, float in_max, uint32_t bits)** defines the mapping
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input range and how many bits output should be generated.
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- **uint32_t map(float value)** maps value to an uint32_t with the appropriate
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number of bits set. These are constrained by the number of bits set in **init()**.
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The output of **map()** is a bit mask and can be used to drive e.g. a led bar etc.
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## Operation
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Suppose you have the following code
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```
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mb.init(0, 100, 10);
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// (binary)
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x = mb.map(64); // x = 111111 ==> 6 bits set, interpolated
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x = mb.map(99); // x = 1111111111 ==> 10 bits set, interpolated
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x = mb.map(4); // x = 0 ==> 0 bits set, interpolated
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x = mb.map(-10); // x = 0 ==> 0 bits set, constrained
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x = mb.map(1000); // x = 1111111111 ==> 10 bits set, constrained
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```
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See examples.
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## Performance
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Indicative performance measured with the **map2bits_performance.ino** example.
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Performance depends on input chosen, platform support of float, and if
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values are constrained (out range) or interpolated (in range)
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Note: time in microseconds per call
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Note: UNO at 16 MHz, ESP32 at 240 MHz
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| board | map - in range | map - out range | notes |
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|:-------:|:---------------:|:-----------------:|:--------|
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| UNO | 45.35 us | 22.20 us | 33% in range, 66% out range
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| ESP32 | | | to do
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## Future
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#### Must
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- update documentation
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- test ESP32
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#### Should
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- extend the idea to applications
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- add examples
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- optimize
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#### Could
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- test other boards
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- **map2bits64(value)** uint64_t for 33 - 64 bits output
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- might need printHelpers
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- **map2bitsDouble(value)** Double version (input range + precision)
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- **map2bitsDouble64(value)** Double version (33 - 64 bits output)
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- uint32_t input version
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- map2DAC?
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- maps a range to analogWrite()..
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- separate class.
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- polarity 0001 <> 1110 ?
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- ~operator
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- MSB/LSB 0001 <> 1000 ?
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- reverse from CRC library
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#### Wont
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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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