Arduino library for SPI based AMT25 series rotary encoder.
Experimental
Warning: This library is not tested with hardware yet. So use with care, feedback welcome.
AMT25 is a library for the AMT253D-V and compatible rotation encoders. This devices decodes 360.0° in 4096 (12 bits) or 16384 steps (14 bits) which implies an accuracy of about 0.088° or even 0.022°.
TODO elaborate.
Families of AMT2x series rotary encoder devices with other interfaces.
| device | protocol | compat | notes |
|---|---|---|---|
| AMT21 | RS485 | x | |
| AMT22 | SPI | YYY | |
| AMT23 | 3-Wire | ? | Simpler, SPI alike, investigate |
| AMT24 | RS485 | x | |
| AMT25 | SPI | YYY |
So far the AMT22 family looks compatible and the AMT23 family might. TODO investigate.
Please note that from the AMT25xy-V there are 8 variations. See datasheet for all details:
- x = Orientation: 2 = Radial (right angle), 3 = Axial (straight)
- y = Absolute Resolution:
- A = 12-bit single-turn, B = 14-bit single-turn
- C = 12-bit multi-turn, D = 14-bit multi-turn
Not all variations are tested.
Hardware SPI connections UNO based upon AMT22
| PIN | Uno Pin | AMT | color1 | color2 | Notes |
|---|---|---|---|---|---|
| +5V | 5V | 1 | White | Green | |
| SCLK | 13 | 2 | Blue | White | |
| MOSI | 11 | 3 | White | Blue | |
| GND | GND | 4 | Green | White | |
| MISO | 12 | 5 | Orange | White | |
| CS | 2 | 6 | White | Orange | Chip Select can be any free pin. |
Angle math
- https://github.com/RobTillaart/Angle
- https://github.com/RobTillaart/AngleConvertor
- https://github.com/RobTillaart/AverageAngle
- https://github.com/RobTillaart/runningAngle
Decoders
- https://www.sameskydevices.com/product/resource/amt25.pdf - datasheet
- https://github.com/RobTillaart/AMT25 this library
- https://github.com/RobTillaart/AS5600 magnetic rotation meter.
- https://github.com/RobTillaart/ERCFS SPI based rotary encoder.
If you have a AMT25 device, please let me know your experiences with the sensor and this (or other) library.
#include "AMT25.h"- AMT25(uint8_t select, SPI_CLASS * mySPI = &SPI) HARDWARE SPI
- AMT25(uint8_t select, uint8_t dataIn, uint8_t dataOut, uint8_t clock) SOFTWARE SPI
- bool begin(uint8_t bits = 14) initializes the communication, set number of bits.
AMT22 and AMT23 derived classes have same constructors.
- uint16_t getRawValue() returns a value from 0..16383
- float getAngle() returns an absolute angle from 0..360.0°, optional with offset correction.
- void setOffset(float offset = 0) set an offset in degrees for the angle.
- float getOffset() returns the current offset in degrees.
- uint16_t setZero() set current position as zero.
- uint16_t getTurns() get number of turns.
- uint32_t lastRead() timestamp in microseconds since start. Note this wraps every ~70 minutes however for RPM measurements one need to read the device far more often.
- void setSPIspeed(uint32_t speed) idem, clipped to max 2 MHz.
- uint32_t getSPIspeed() idem.
- bool usesHWSPI() idem.
- improve documentation
- test with hardware
- test compatibility ANT22 / AMT23
- add examples
- add convenience getter for steps / bits
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