SOMANET Sense REM 16MT

Overview

../../../../_images/REM-16MT_top.jpg

The REM 16MT features an energy harvesting system enabling battery-free multi-turn functionality. A magnetic hall effect-based sensor combined with a N/S magnet mounted on the rotating shaft serves as the main source of angle information. The single-turn position is absolute.

The 12 bit Multi-turn feature allows 4096 turns to be detected and stored.

Technical Specification

Parameter Value
Single-turn absolute position sensing YES
Multi-turn absolute position sensing YES (no external power supply required)
Single turn resolution 16 bit
Multi turn resolution 12 bit (4096 turns)
Update frequency 14 kHz
Communication protocol proprietary over SPI
Overall latency (incl. SPI communication) < 70 microseconds
Independent linearity (non-calibrated) ±1%
Independent linearity (calibrated) ±0.3%
Max. hysteresis 0.1°
Max. repeatability 0.1°
Max. radial mounting misalignment ±0.2mm
Operating temperature -25°C to +80°C
Operation Voltage 5 V DC
Dimensions H x W x D [mm] 9.3 x 36 x 18.5
Weight 7 g

Electrical installation

SPI connectors

Two alternative SPI connectors are available, JST SM06B-GHR-TB (top) and JST SM08-SURS-TF (bottom) with following pinout. For pin 1 see image below table.

Pin JST SM06B-GHR-TB Explanation
1 VCC (5V) Supply Voltage
2 MOSI Master Output Slave Input
3 MISO Master Input Slave Output
4 GND Ground
5 SCK Clock
6 SS Sensor Enable (Chip Select)
Pin JST SM08-SURS-TF Explanation
1 Not in use
2 SS Sensor Enable (Chip Select)
3 SCK Clock
4 GND Ground
5 MISO Master Input Slave Output
6 MOSI Master Output Slave Input
7 VCC (5V) Supply Voltage
8 Not in use
../../../../_images/rem_16mt_drawing.png

Mechanical assembling manual

Important

Please consider before dismounting that once the sensor is dismounted, the calibration can be undone and the calibration process has to be repeated.

For mounting the Encoder M3 Screws are to be used to ensure maximum centering. The maximum allowed radial missalignment is +/-0,2mm. The air gap between the sensing chip is to be min. 3mm and max. 4mm.

Mounting Scheme

../../../../_images/rem16mt_mount_scheme.png

Mechanical Dimensions

../../../../_images/rem_16mt_dimensions.png ../../../../_images/rem_16mt_dimensions_front.png
Parameter Min Typ Max
Supply voltage (VDC) 4.5V 5V 5.5V
Supply current   15mA  
Reverse polarity protection of power supply   No  
Serial input parameters (SEN, SCK, MOSI) Min Typ Max
Voltage range 0V   5V
LOW-level voltage range 0V   1V
HIGH-level voltage range 2.4V   5V
Pullup current (@0V)     60µA
Serial input parameters (SEN, SCK, MOSI) Min Typ Max
Voltage range 0V   3.3V
LOW-level voltage range 0V   0.4V
HIGH-level voltage range 2.9V   3.3V
Nominal output current -4mA   +4mA
Short circuit output current -45mA   +50mA

Readout Mode

Timing Diagram

../../../../_images/rem_16mt_timing_readout.png
Time Min Description
t1 10µs Data buffer is filled with the data of the previous acquisition.
t2 250ns (4MHz) Minimal clock period time.
t3 10µs Transfer reset, the MISO pin is pulled up during SEN high phase.

The transfer can be interrupted at any time by returning the SEN pin to the high state.

Data Format

The most significant bit is transferred first. The following table describes the transferred data bits on the MISO pin:

Bit Range Bit Size Description
D[60..63] 4

Status flags:

-> 0x0: the sensor position is valid

-> 0x1: an error occurred at startup in the ST stage (weak magnetic field)

-> 0x2: an error occurred at startup in the MT stage (counter error)

-> 0x3: an error occurred in the ST calculation stage (cordic error)

-> 0x4: an error occurred in the MT calculation stage (speed overflow)

-> 0xA: an error occurred in the filter stage (wrong configuration)

-> 0xB: an error occurred in the filter stage (speed overflow)

-> 0xD: an error occurred in the last configuration (unknown command)

-> 0xE: an error occurred in the last configuration (process failed)

In the case of an error state, the following must be done:

-> 0x1-0x4: since the correct MT value can no longer be evaluated, the last valid output position is frozen until a reboot or reset

-> 0xA-0xB: the actual output position is invalid, but the state is changing to valid when the error is gone

-> 0xD-0xE: at least one configuration command failed, reboot or reset to clear this state

D[48..59] 12 Multi turn position (MT)
D[32..47] 16 Filtered single turn position (ST)
D[16..31] 16

Raw single turn position (RST)

-> the difference between ST and RST is just the noise; direction and offset are identical and offset are identical
D[8..15] 8 Timestamp in microseconds
D[0..7] 8 Checksum over all the other data bytes checksum := 0x5A xor (1+D[8..15]) xor (2+D[16..23]) xor (3+D[24..31]) xor (4+D[32..39]) xor (5+D[40..47]) xor (6+D[48..55]) xor (7+D[56..63])

Configuration Mode

Timing Diagram

../../../../_images/rem_16mt_timing_config.png
Time Max Description
t1 10µs Data buffer is filled with the data of the previous acquisition.
t2 250ns (4MHz) Minimal clock period time.
t3 10µs Transfer reset, the MISO pin is pulled up during SEN high phase.
t4 10µs After this phase the MISO pin is pulled low to indicate that the execution is in progress.
t5 200ms Execution of the commanded configuration, do not switch off the power supply!
t6 6µs During SEN is going LOW, the MOSI pins must be HIGH at least until the MISO pin is driven.

Data Format

The MISO data format is the same as by the readout mode described above.

The most significant bit is transferred first. The following table describes the transferred data bits on the MOSI pin:

Bit Range Bit Size Description
C[48..55] 8 Command opcode, see detailed description below.
None, C[40..47], C[32..47] or C[16..47] 0, 8, 16 or 32 The data bits of the configuration command. The size is depending on the specific command, see table below.

Configuration Commands

Command Opcode Data Bits Description
0x00 0 CTRL_RESET – software reset of the sensor
0x55 8

CONF_DIR – change the direction of the sensor

-> write 0x00 for CW

-> write 0x01 for CCW

0x56 0 CONF_NULL – the actual sensor position will be used as new zero output (ST+MT)
0x57 32 CONF_PRESET – the data bits define the new output value (ST+MT)
0x50 16

CONF_STPRESET – the data bits define the new ST output value

-> it is not recommended to use this command close to the single turn discontinuity point, since the resulting MT output value can be different to what is expected
0x59 16

CONF_MTPRESET – the 12 lower data bits define the new MT output value

-> it is not recommended to use this command close to the single turn discontinuity point, since the resulting MT output value can be different to what is expected
0x5B 8

CONF_FILTER – the filter of the sensor

-> write 0x00 to switch off the filter

-> write 0x02-0x09 to set the corresponding filter, F is one of 2-9

The estimated step response time of the filter is Ts*2^F (Ts is the sampling time, ca. 70µs)

0x3D 16

CALIB_TBL_SIZE – start a calibration with the given table size, one of 4,8,16,..,256

-> additional, the offset and direction settings are reset to zero

-> it is recommended to use a strong filter (e.g. F=9) during calibration

-> wait at least 200ms until starting the calibration with the first point

0x3E 16

CALIB_TBL_POINT – setup a calibration point

-> before this, the magnet must be positioned to the corresponding angle

-> from point to point, the magnetic angle must be increased in CW direction

-> the first point must be 0, then 1, ..., the last point is [table size - 1]

-> after sending the last point, the table is saved directly to the flash memory

0x1C 0

CTRL_SAVE – save the calibration and configuration data to flash

-> it is recommended to send a reset command after saving

Important

Do not switch off the power supply during configuration, else the flash can become corrupted.

In the case of a wrong command or a failure in configuration, the error state is set until the next reboot or reset.

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