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