ess_matlab_rpi

Examples for communicating with an Epson IMU with SPI interface using a Raspberry PI

Disclaimer

---

This is free and unencumbered software released into the public domain.

Anyone is free to copy, modify, publish, use, compile, sell, or distribute this software, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means.

In jurisdictions that recognize copyright laws, the author or authors of this software dedicate any and all copyright interest in the software to the public domain. We make this dedication for the benefit of the public at large and to the detriment of our heirs and successors. We intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

For more information, please refer to https://unlicense.org

Purpose of this software

---

This is demonstration software for evaluation purpose to communicate using Matlab with a supported Epson sensor connected to a Raspberry Pi that is networked to a PC. The user is expected to modify the scripts and extend the functionality to meet their specific evaluation requirements.

Test machine

---

• WIN10 Pro 64-bit/PC Core i5-6500 @ 3.2GHz, 16GB RAM
• Matlab R2018a (9.4.0.813654) 64-bit
• Raspberry Pi B+
  • Raspberry Pi connected to Epson IMU with SPI Interface using Epson M-G32EV031 Breakout Board
  • Epson IMU M-G3xx & Epson Accel M-A352AD10
  • Direct Ethernet Connection between PC <--> RPi

Requirements

---

• This requires a PC running MATLAB R2018a and MATLAB Support Package for Raspberry Pi Hardware v18.1.3 web link

• This requires a PC connected by ethernet to the Raspberry Pi with Epson IMU attached to the SPI interface (UART interface is not supported).

• This assumes using customized version of Mathwork's Raspberry Pi OS installed on the Raspberry Pi Hardware and communicating with Matlab on the PC using an ethernet connection as part of the MATLAB Support Package for Raspberry Pi Hardware v18.1.3

Important for RPi SPI Interface

---

1. The MATLAB Support Package for Raspberry Pi should already enable the SPI interface on the Raspberry Pi.

2. This example is designed with the following pin-mapping:

Epson IMU	Raspberry Pi
Epson_RESET#	RPI_GPIO_P1_15 (GPIO22)
Epson_DRDY	RPI_GPIO_P1_18 (GPIO24)
Epson_CS	RPI_GPIO_P1_24 (GPIO08)/CE0
Epson_SCK	RPI_GPIO_P1_23 (GPIO11)
Epson_MISO	RPI_GPIO_P1_21 (GPIO9)
Epson_MOSI	RPI_GPIO_P1_19 (GPIO10)

How to use this software

---

1. Create a new object using the Epson Sensor model connected to the RPI SPI interface within Matlab.

   Specify the 3 interface parameters for SPI clock speed, Reset pin, DRDY pin as required for your hardware configuration.

   If the selected device model has a variant (i.e. G365PDF1 or G365PDC1, then a 4th parameter may be required to differentiate between model variants).

   Otherwise, passing no parameters keeps the assignments as default: speed=100000Hz, RpiPinReset=22, RpiPinDrdy=24

   For example, the default:

>> e = G365Imu(1000000, 22, 24);
RESET# pin: 22
DRDY pin: 24
Toggle RESET#
Check NOT_READY
No Errors Detected
Model: G365PDF1
Version: 40.20
Serial#: X0000013

For example, in the case of SPI=500000, RpiPinReset=23, RpiPinDrdy=18;

>> e = G365Imu(500000, 23, 18);
RESET# pin: 23
DRDY pin: 18
Toggle RESET#
Check NOT_READY
No Errors Detected
Model: G365PDF1
Version: 40.20
Serial#: W0000501
>>

The above will create handle object "e" representing the Epson Sensor connected to the RPI SPI interface. A hardware reset is always asserted to place the Epson IMU in a known state. Then the model number, version code, and serial number is read from the device.

2. Configure the device's burst output fields by writing a 1 to desired object properties to enable the specific burst fields.

   For IMU Devices

   NOTE: Some IMU fields support 32-bit output which can be set by writing a 2

   Object Property	Description
   Ndflag	Enable NDFLAG field in burst sample, 16-bit only
   TempC	Enable TEMPC field in burst sample 1=16-bit 2=32-bit
   Gyro	Enable or disable Gyro X,Y,Z 1=16bit 2=32-bit
   Accl	Enable or disable Accl X,Y,Z 1=16bit 2=32-bit
   DeltaA	Enable or disable Delta Angle X,Y,Z 1=16bit 2=32-bit
   DeltaV	Enable or disable Delta Velocity X,Y,Z 1=16bit 2=32-bit
   Quaternion	(Only for G330, G366, G365) Enable or disable Quaternion q0,q1,q2, q3 1=16bit 2=32-bit
   Atti	(Only for G330, G366, G365) Enable or disable Attitude ANG1, ANG2, ANG3 1=16bit 2=32-bit
   Gpio	Enable GPIO field in burst sample 16-bit only
   Counter	Enable 16-bit COUNT field in burst sample
   Chksm16	Enable 16-bit CHKSM field in burst sample
   Set16G	* (Only for G330, G366, G370PDG0, G370PDT0) Set accelerometer range 0=8G 1=16G

   For Accelerometer Devices:

   Object Property	Description
   Ndflag	Enable 16-bit NDFLAG field in burst sample
   TempC	Enable 32-bit TEMPC field in burst sample
   Counter	Enable 16-bit COUNT field in burst sample
   Chksm16	Enable 16-bit CHKSM field in burst sample
   TiltX	Enable tilt output on X axis instead of accelerometer by setting to 1
   TiltY	Enable tilt output on Y axis instead of accelerometer by setting to 1
   TiltZ	Enable tilt output on Z axis instead of accelerometer by setting to 1

3. Select the desired output rate & filter setting by setting the object properties.

   For IMU Devices

   Object Property	Description
   DoutRate	2000, 1000, 500, 250, 125, 62.5, 31.25, 15.625, 400, 200, 100, 80, 50, 40, 25, 20
   FilterSel (All IMUs, and for G370PDF1 & G370PDS0 when DoutRate=2000, 400, or 80sps)	tap0, tap2, tap4, tap8, tap16, tap32, tap64, tap128, 32fc50, 32fc100, 32fc200, 32fc400, 64fc50, 64fc100, 64fc200, 64fc400, 128fc50, 128fc100, 128fc200, 128fc400
   FilterSel (Only for G370PDF1 & G370PDS0 when DoutRate is not 2000, 400, or 80sps)	tap0, tap2, tap4, tap8, tap16, tap32, tap64, tap128, 32fc25, 32fc50, 32fc100, 32fc200, 64fc25, 64fc50, 64fc100, 64fc200, 128fc25, 128fc50, 128fc100, 128fc200

   NOTE: Refer to device datasheet for valid combinations of Output Rate vs Filter Selection i.e. For M-G3xx, Table 5.4 Supported Settings For Output Rate and Filter Cutoff Frequency

   For Accelerometer Devices

   Object Property	Description
   DoutRate	1000, 500, 200, 100, 50
   FilterSel	64fc83, 64fc220, 128fc36, 128fc110, 128fc350, 512fc9, 512fc16, 512fc60, 512fc210, 512fc460

   NOTE: Refer to device datasheet for valid combinations of Output Rate vs Filter Selection i.e. For M-A352AD, Table 5.4 Supported Settings For Output Rate and Filter Cutoff Frequency

4. Optionally enable other operating modes

   For IMU Devices

   Object Property	Description
   Gpio2Sel	GPIO2 pin function can be gpio, counter_reset, or external_trigger

   For Accelerometer Devices

   Object Property	Description
   ReducedNoiseEn	Reduce Noise Floor mode
   TempStabEn	Bias stabilization against thermal shock
   ExtEnable	External Trigger mode on falling edge

5. To initialize the Epson sensor with current object properties run the setDeviceCfg() method.

   This method should be called after any changes to the object properties to propagate the changes to the sensor device.

>> e.setDeviceCfg;

6. To retrieve scaled sensor data and store it in an array call the getScaledSamples(n) method while specifying the "n" as the number of sensor samples to read.

For example to store 500 samples to the scaleddata structure:

>>scaleddata = e.getScaledSamples(500);

The above command will store the incoming scaled (converted) sensor data into an array while managing the SPI interface as follows:

• If not already, place the device into SAMPLING mode
• Checks for DRDY assertion
• Send Burst Command
• Burst Read Sensor Data (n samples)
• Post processes the captured sensor data by applying the appropriate scale factors

The default settings unless changed:

For IMU Devices

• Output date rate = 250Hz
• Filter = Moving Average TAP=16
• Burst Output = Ndflag, 16-bit TempC, 16-bit Gyro X,Y,Z, 16-bit Accl X,Y,Z, 16-bit Sample Counter, Chksm16

For Accelerometer Devices

• Output date rate = 200Hz
• Filter Tap = 512 TAP Fcutoff = 60Hz
• Burst Output = Ndflag, 32-bit TempC, 32-bit ACCL X,Y,Z, 16-bit Sample Counter, Chksm16

Precautions For Processing Speed

Due to processing latency of connection MATLAB --> RPi --> Epson Device & capability of the RaspberryPi hardware, IMU output rate may be limited. Data output rate above 200Hz may not be stable.

If IMU sensor data can not be processed within data output rate timing, DRDY toggling will not be consistent and captured sensor data may have dropped sensor samples. Verify the processing speed/data rate by monitoring the DRDY toggle rate by an oscilloscope probe which should be equal to the specified DoutRate.

EpsonDeviceRpi Object Description

---

• Object properties must be propagated to the physical device register by calling the setDeviceCfg() method after properties are configured.
• To back propagate device register settings to the object properties call the getDeviceCfg() method

Properties For IMU Devices

---

Property	Description
Accl	Enable or disable Accl X,Y,Z 1=16bit 2=32-bit
Atti	(Only for G365, G330, G366) Enable or disable Attitude ANG1, ANG2, ANG3 1=16bit 2=32-bit
BytesPerBurst	Status indicating # of bytes per burst sample
Chksm16	Enable 16-bit CHKSM field in burst sample
Counter	Enable 16-bit COUNT field in burst sample
DeltaA	Enable or disable Delta Angle X,Y,Z 1=16bit 2=32-bit
DeltaV	Enable or disable Delta Velocity X,Y,Z 1=16bit 2=32-bit
DoutRate	Output rate in Hz
ExtEnable	Enable External Trigger
FieldsInBurst	Status indicating fields in burst sample
FieldsPerBurst	Status indicating # of fields per burst sample
FilterSel	Filter selection
Gpio	Enable GPIO field in burst sample
Gpio2Sel	GPIO2 pin function can be gpio, counter_reset, or external_trigger
Gyro	Enable or disable Gyro X,Y,Z 1=16bit 2=32-bit
Ndflag	Enable NDFLAG field in burst sample
Quaternion	(Only for G365, G330, G366) Enable or disable Quaternion q0,q1,q2,q3 1=16bit 2=32-bit
Sampling	Status indicating SAMPLING mode
TempC	Enable TEMPC field in burst sample 1=16-bit 2=32-bit
Set16G	(Only for G330, G366) 0=8G 1=16G accelerometer output range
IsPDC1	(Only for G365) 0=G365PDF1 1=G365PDC1
IsPDCA	(Only for G364) 0=G364PDC0 1=G364PDCA
IsPDS0	(Only for G370PDF1, G370PDS0) 0=G370PDF1 1=G370PDS0
IsPDT0	(Only for G370PDG0, G370PDT0) 0=G370PDG0 1=G370PDT0
ProdId	Detected device Product ID from reading device registers
Version	Detected device Version from reading device registers
SerialId	Detected device Serial Number from reading device registers
Sensor	Sensor SPI object on Raspberry Pi
rpi	Raspberry Pi object

Properties For Accelerometer Devices

---

Property	Description
BytesPerBurst	Status indicating # of bytes per burst sample
Chksm16	Enable 16-bit CHKSM field in burst sample
Counter	Enable 16-bit COUNT field in burst sample
DoutRate	Output rate in Hz
ExtEnable	Enable External Trigger
FieldsInBurst	Status indicating fields in burst sample
FieldsPerBurst	Status indicating # of fields per burst sample
FilterSel	Filter selection
Ndflag	Enable NDFLAG field in burst sample
ReducedNoiseEn	Enable Reduce Noise Floor mode
Sampling	Status indicating SAMPLING mode
TempC	Enable TEMPC field in burst sample
TempStabEn	Enable Bias Stabilization Against Temperature mode
TiltX	Enable Tilt for X-axis in burst sample instead of acceleration
TiltY	Enable Tilt for Y-axis in burst sample instead of acceleration
TiltZ	Enable Tilt for Z-axis in burst sample instead of acceleration
ProdId	Detected device Product ID from reading device registers
Version	Detected device Version from reading device registers
SerialId	Detected device Serial Number from reading device registers
Sensor	Sensor SPI object on Raspberry Pi
rpi	Raspberry Pi object

Object Methods

---

• Preferred method to configure the device is by setting the object properties and then calling the setDeviceCfg() method to write properties to the appropriate registers
• However, there are methods to access the device registers directly if needed
• Reading device register values directly by calling readReg() method
• To pass the register address to the readReg(), simply use the object_name.REG_NAME

For example to read MODE_CTRL register REG[0x02(W0)]:

>> e.readReg(e.MODE_CTRL, true);
REG[0x02 (W0)] > 0x0400

• Writing to device register values directly by calling the writeRegH() or writeRegL() methods to write to the HIGH byte or LOW byte respectively.
• NOTE: After writing directly to device registers, run getDeviceCfg() method to synchronize the object properties with current device register settings

For example to write a 0x01 to the HIGH byte of MODE_CTRL register REG[0x02(W0)]:

>> e.writeRegH(e.MODE_CTRL, 1, true);
REG[0x03 (W0)] < 0x01

For example to write a 0x06 to the LOW byte of MSC_CTRL register REG[0x02(W1)]:

>> e.writeRegL(e.MSC_CTRL, 6, true);
REG[0x02 (W1)] < 0x06

Methods For IMU & Accelerometer Devices

Methods	Description
dumpReg	Read back all register values
getDeviceCfg	Update object properties by reading device registers
getModel	Read back MODEL number
getScaledSamples	Call getSampling() and convert data to scaled values
getSerialId	Read back SERIAL_NUM
getVersion	Read back VERSION number
gotoConfig	Go to CONFIG mode
gotoSampling	Go to SAMPLING mode
printTabular	Output a table listing with specified scaled sensor data
readReg	Read a 16-bit value from specified WIN_ID & register address
resetDevice	Assert hardware reset on RESET# pin and wait RESET_DELAY
setDeviceCfg	If not already goto CONFIG mode and program device registers
writeRegH	Write to HIGH byte of specified WIN_ID & register address
writeRegL	Write to LOW byte of specified WIN_ID & register address

Additional Methods For IMU Devices

Methods	Description
testFlash	Sets Flash test bit and waits for bit to clear to check result
testSelf	Sets selftest bit and waits for bit to clear to check result

Additional Methods For Accelerometer Devices

Methods	Description
doSelftests	Perform device self tests (testSENS, testFlash, testACC, testTEMPC, testVDD)

File Listing

---

File	Description
EpsonDeviceRpi.m	Handle object base class for Epson sensor device connected by SPI to RPI controlled by Matlab
A352Accl.m	Epson A352 Sensor object derived from base class EpsonDeviceRpi
G320Imu.m	Epson G320 Sensor object derived from base class EpsonDeviceRpi
G330_G366Imu.m	Epson G330PDG0/G366PDG0 Sensor object derived from base class EpsonDeviceRpi
G354Imu.m	Epson G354 Sensor object derived from base class EpsonDeviceRpi
G364Imu.m	Epson G364PDCA/PDC0 Sensor object derived from base class EpsonDeviceRpi
G365Imu.m	Epson G365PDF1/PDC1 Sensor object derived from base class EpsonDeviceRpi
G370F_G370SImu.m	Epson G370PDF1/PDS0 Sensor object derived from base class EpsonDeviceRpi
G370G_G370TImu.m	Epson G370PDG0/PDT0 Sensor object derived from base class EpsonDeviceRpi
exampleEpsonAcclRpi.m	Example matlab script creating Epson Accelerometer RPI object, configure, get sensor samples, print sensor data to console, plot
exampleEpsonImuRpi.m	Example matlab script creating Epson IMU RPI object, configure, get sensor samples, print sensor data to console, plot
createAcclPlot.m	Plot Accl X,Y,Z axes
createGyroPlot.m	Plot Gyro X,Y,Z axes
README.md	This readme file in markdown

Change Record

---

Date	Version	Description
2021-10-13	v1.0	Initial release
2023-01-10	v1.01	Minor maintenance, add G330/G366 support, fix deltaV scalefactor G365PDC1, formatting
2023-08-17	v1.02	Minor maintenance, add G370PDG0/G370PDT0 support, minor renaming of IMU properties