OpenPlotter3 – Sensors_a


Recently I revisited OpenPlotter after a two year interval to see what had changed in the latest version 3 (Ref.1). I tested the Starter and Headless images and setup AIS & GPS on OpenCPN. In 2021 I had looked at various aspects of version 2 (Ref.2/12). In this post I will look at the Starter image and connection of a GY-91 sensor module

Starter Image Setup

Fig.1 OpenPlotter3 Desktop
Fig.2 Raspberry Pi Configuration
Fig.3 OpenPlotter3 Settings After Boot
Fig.4 OpenPlotter3 Settings After Update
Fig.5 System Check with Warnings
Fig.6 Signal K Dashboard after Login as Admin
Fig.7 Notifications for Signal K Admin Approval
Fig.8 System Check After Signal K Admin Approval
Fig.9 PyPilot Approval Request in Signal K Server

I first downloaded the RPi4_32bit starter image 22_07_18. I used Windows Disk Manager to delete the boot/linux partitions on a spare 32Gbyte SD card (cuidado-don’t wipe the wrong disk) and wrote the image using Raspberry Pi Imager. I then inserted the SD card and connected the RPi4 to a mouse/keyboard/HDMI_TV/Internet connection. The boot up process went smoothly into the OpenPlotter Desktop as in Figure 1. After this, I used the RPi Configuration to enable SSH/VNC/I2C in order to control the RPi over a LAN and use the various I2C sensors as in Figure 2.

I connected the RPi4 over the LAN and logged in with VNC viewer. I then changed the default password. After this, I checked the Settings Menu as in Figure 3. I updated all the packages that were indicated as in Figure 4. Finally I installed GPIO & I2C. I ran System Check again and noticed 4 warning messages (PyPilot installed later) as in Figure 5. Unlike version 2, the Signal K server has to approve these connections. Open Signal K server and create an Admin account and login as in Figure 6. Open Notifications and press “Approve” as in Figure 7. This will send four messages to Signal K. Click on each message and change permissions to Read/Write and Approve. Redo System Check to ensure no warnings as in Figure 8. Figure 9 shows the Approval Request of PyPilot in Signal K with the permissions changed to Read/Write.

GY-91 Connection

Fig.10 GY-91 Sensor Module Connection to RaspberryPi4
GY-91 ModuleRPi4 GPIO
Vin5V pin 2
SDASDA pin 3
SCLSCL pin 5
GrndGrnd pin 9
Fig.11 GY-91 to RPi4 Wiring

Figure 10 shows the sensor module connection. I used short female to female pin header leads running through the top access of the RPi4 housing. Figure 11 shows the wiring. There are two 5VDC pins on the RPi4, I previously used pin 4 for a fan.

Sensor Configuration

Fig.12 I2C Addresses $68 & $76
Fig.13 Pressure Sensor BMP280 Added
Fig.14 PyPilot IMU Enabled and MPU-9250 Detected
Fig.15 Signal K Server Dashboard Showing Activity
Fig.16 Signal K Instrument Panel Showing BMP280 & MPU2950 Data

Open I2C and check the visible addresses as in Figure 12. $76 is the BMP280 air pressure/temperature sensor. Add this sensor as in Figure 13. Now open PyPilot and enable the IMU9250 as in Figure 14. Figure 15 shows the Signal K server activity and Figure 16 shows the Signal K instrument panel.

Fig.17 YouTube Video OpenPlotter3 – Sensors_a

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#1. – “OpenPlotter3 Headless for GPS and RTL-SDR AIS on RPi4”

#2. – “OpenPlotter – RRi4 – Headless_b”

#3. – “OpenPlotter – Rpi4 – USBpwr”

#4. “Open Plotter – RPi4 Headless_a”

#5. “OpenPlotter – GRIB Files”

#6. – “OpenPlotter – Sensors_b”

#7. – “OpenPlotter – AIS+”

#8. – “OpenPlotter – Sensors_a”

#9. – “OpenPlotter – RTL-SDR for VHF/AIS”

#10. – “OpenPlotter – AIS Connection”

#11. – “OpenPlotter – GPS Connection”

#12. -“OpenPlotter – Naviagtion System on RPi”

By Jeremy Clark

Jeremy Clark is a Senior Telecommunications Engineer and Advanced Amateur Radio Operator VE3PKC. He is the author of E-Books on Telecommunications, Navigation & Electronics.