Low-level software for the Newcastle University ROV 2021. Takes key:value pairs from Raspberry Pi in MsgPack format and acts on them accordingly.
Designed for Arduino Nano 33 BLE but should also be fully functional for Arduino Mega 2560 or similar.
You need to install the following libraries in your IDE:
Arduino A and Arduino B have different pin assignments as shown below. By default, the code assumes it is running on Arduino A. To switch it to Arduino B, connect pin 17 to GND.
Thrusters are given an ID which describes their position on the ROV. Motors are named in a similar fashion.
| Device Name | Key | Attached to | Pin | Location |
|---|---|---|---|---|
| Top Forward Port Thruster (front left) | T_VFP | Arduino A | 2 | Enclosure 1 |
| Top Forward Starboard Thruster (front right) | T_VFS | Arduino A | 3 | Enclosure 1 |
| Top Aft Port Thruster (back left) | T_VAP | Arduino A | 4 | Enclosure 1 |
| Top Aft Starboard Thruster (back right) | T_VAS | Arduino A | 5 | Enclosure 1 |
| Forward Port Thruster (front left) | T_HFP | Arduino B | 2 | Enclosure 2 |
| Forward Starboard Thruster (front right) | T_HFS | Arduino B | 3 | Enclosure 2 |
| Aft Port Thruster (back left) | T_HAP | Arduino B | 4 | Enclosure 2 |
| Aft Starboard Thruster (back right) | T_HAS | Arduino B | 5 | Enclosure 2 |
| Arm Gripper Motor | M_G | Arduino B | 6 | Enclosure 2 |
| Micro ROV return cord | M_C | Arduino B | 7 | Enclosure 2 |
| Micro ROV Thruster | T_M | Arduino B | 8 | Enclosure 2 |
| Arduino A | A_A | Raspberry Pi | Enclosure 1 | |
| Arduino B | A_B | Raspberry Pi | Enclosure 2 |
| Key | Min | Max |
|---|---|---|
| T_VFP | 1100 | 1900 |
| T_VFS | 1100 | 1900 |
| T_VAP | 1100 | 1900 |
| T_VAS | 1100 | 1900 |
| Key | Min | Max |
|---|---|---|
| ID | A_A | A_A |
| S_A | - | - |
| Key | Min | Max |
|---|---|---|
| T_HFP | 1100 | 1900 |
| T_HFS | 1100 | 1900 |
| T_HAP | 1100 | 1900 |
| T_HAS | 1100 | 1900 |
| M_G | 1200 | 1800 |
| M_C | 1350 | 1650 |
| T_M | 1100 | 1900 |
| Key | Min | Max |
|---|---|---|
| ID | A_B | A_B |
| S_B | - | - |
These will be returned with the S_A or S_B keys.
| Status Code | Description |
|---|---|
| 0 | No error |
| 1 | Outputs halted |
| 2 | Left limit hit. Motor stopped |
| 3 | Right limit hit. Motor stopped |
| 4 | Arduino booting |
| 5 | Heartbeat |
| -1 | Received value out of range |
| -6 | This is not an Output Arduino |
| -7 | This is not an Input Arduino |
| -8 | Invalid Output device key |
| -9 | Invalid Input device key |
| -10 | Can't stop outputs on an Input Arduino |
| -11 | Incoming data parsing failed |
| -12 | Arduino ID is not set up |
| -13 | No messages received, outputs halted |
| -23 | Index not valid for setting a sensor parameter |
The Arduino Nano has an RGB LED which is used for debugging.
| Colour | Meaning |
|---|---|
| 🔴Red | Waiting for data from Pi. Outputs disabled for safety. |
| 🟢Green | Everything working as expected |
| 🔵Blue | Unused |
| 🟡Yellow | Waiting for data from Pi |
| 🟣Purple | Loading/processing data |
| Cyan | Data parsing successful |
The arduino runs arduino-main.ino which imports from the src directory. In terms of structure, the most interesting parts are in the equipment directory. Each device which could be connected has its own class.
This code is ultimately the third iteration of the 2018-19 Arduino code.
A lot of the code is structured around the Mapper class. This class acts in a broadly similar way to a Java Hashmap. It has key:value pairs where the key is a string (the JSON ID of that device) and the value is an object which inherits from either Input or Output.
All motors in this implementation are the Blue Robotics T100/T200/M100 which are controlled via PWM. Each of these classes inherits from the EscMotor class, which in turn inherits from Output. You set the speed of the motor using the setValue() method. For these motors it will take values in the range 1100-1900, where 1500 is stopped. Devices are controlled when an associated key:value pair is received from the Pi.
Sensors all inherit from the Input base class. You can read the sensor value from the getValue() method, and set any attributes of that sensor with setParam(). Sensors are polled once per loop.