Pluto Pico

We noticed that in previous groups the project was lacking embedded software developers. Each group always started their project by running motors from scratch. In order for the project to grow each year this needs to stop!

That’s why pluto-pico exists. Pluto-pico encapsulates any embedded software part and to make it easy to use and most suitable for pluto and its future developers.

Pluto can be used independently to any system. All it needs is a USB host in order to connect to the pluto-shell. That can be a raspberry pi but also any kind of computer.

Pluto-pico is also cheap since it runs on a 7.50€ raspberry-pico making so it is possible for for any project participant to have one pluto-pico to test and verify.

Pluto-shell provides a user-friendly and easy to use interface to test motordrivers or sensors that are used for Pluto.

Since the application has been developed as a zephyr application it is also possible to exchange the microcontroller or do any changes on the embedded part.

System

Pluto-pico parts functions
Functional component	Amount	Positioning	Function
Relay	8 (on one PCB)	No special needs Please review datasheet for dimensions	Switches various electrical loads. Such as: Lights, Fan, beer-cooler
Motordriver	2 (on one PCB)	No special needs Please review datasheet for dimensions	Controls motor speed of each motor (left & right) Defines speed & direction of Pluto
Distance sensor	4	Positioned at each chain track (one in front, one in the back) Please review datasheet for dimensions and specs special requirements to visual area apply!	Measures distances of each chain to obstacle of that chain Will act as a part of safety concept to stop Pluto if an movement is not possible.
GPS	1	Consists of antenna and module Antenna needs to be flat and exposed to sky	Determines current position and speed of Pluto
Orientation	1	Needs to be away of any magnets and flat	Determines current orientation & acceleration of Pluto
Temperature sensor	3	Needs to be at location of temperature measurement	Determines current temperature of: Battery cells, pluto-ros2 or Beer
Battery cell measurement	4	No special needs	Monitoring voltage of battery cells
Emergency Switch	1	Needs to be reachable for Pluto users	Emergency switch to turn OFF PLuto at any moment

Microcontroller

Pluto_pico uses the Raspberry Pi Pico microcontroller. To communicate with pluto-pico use the pluto-shell. Simply connect a usb-cable to and open a serial connection. A list of supported commands can be found in the table below.

Working with Pluto_pico

Introduction

Pluto_pico simplifies the process of developing embedded applications, allowing developers to focus on higher-level functionality. Designed specifically for the Raspberry Pi Pico, it leverages the capabilities of the RP2040 microcontroller to provide a robust and versatile platform for robotics and other embedded projects.

Prerequisites

Before beginning, ensure you have the following:

A Raspberry Pi Pico with an RP2040 microcontroller
A USB cable compatible with the Raspberry Pi Pico
The zephyr.uf2 file specific to the Pluto_pico project

Flashing Pluto_pico

1. Prepare the Hardware: Connect the Raspberry Pi Pico to your host PC using the USB cable. Ensure that you hold down the BOOTSEL button on the Pico while connecting.

2. Enter Mass Storage Mode: Once connected, release the BOOTSEL button. Your Raspberry Pi Pico will now operate as a mass storage device.

3. Flash the Firmware: Drag and drop the zephyr.uf2 file onto the Raspberry Pi Pico drive. This process will flash the firmware to the Pico’s internal flash storage. This step is necessary once for each version of the firmware.

Using the Pico-Shell (version >= v0.1.0)

Establish a Serial Connection:
- To interact with Pluto_pico using the pico-shell, a serial port connection is required.
- You can use a terminal program like PuTTY or minicom on your PC to connect to the serial port. The specific port can be found in your system’s device manager (for Windows) or /dev directory (for Linux and macOS).
- Select a baudrate of 115200 in your terminal program.
Verify the Connection:
- Once connected, the onboard LED on the Raspberry Pi Pico will start flashing at a frequency of 1 second. This indicates a successful serial connection.
Using Pico-Shell:
- Once connected via the terminal program, you can interact with the Pluto_pico through various commands.
- The pico-shell allows you to configure and control external peripherals, read sensor data, and manage the robot’s operations. Try one of the commands from the following table.

Command Overview

The following table contains in short all available commands.

Explore the detailed command list and examples provided in the subsequent sections to fully utilize the capabilities of Pluto_pico.

Happy developing!

Pluto Protocol
Command	Description	Supported Arguments
`ANY_COMMAND`	Calling without arguments: Detailed info about command only excpetion: `version`	`--help` short info about command
`echo`	returns <message> pluto-pico version: >= v0.1.0	`<message>` respond with message
`version`	returns pluto-pico version no argument := APP_VERSION_STRING pluto-pico version: >= v0.1.0	`--build-ver` APP_BUILD_VERSION
`relays`	control relays of pluto-pico pluto-pico version: >= v0.1.0	`--set-bytes <value[0..0xFF]>` `--set-relay <name> <state[0\|\|1]>` `--list-relays` pluto-pico version: >= v0.2.0: `--get-relay <name>`
`motor1`	control motor1 of pluto-pico pluto-pico version: >= v0.3.0	`set-dir <state[0\|\|1]>` `set-speed <value[0..100]>` (unsafe) `Zset-speed <value[0..100]>` `get-speed` `get-dir` `get-motor` `config-acc-rate <value[0..100]>` `config-brak-rate <value[0..100]>` `config-acc-rate-delay <value[0..0xFFFF]ms>` `config-brak-rate-delay <value[0..0xFFFF]ms>`
`motor2`	control motor2 of pluto-pico pluto-pico version: >= v0.3.0	`set-dir <state[0\|\|1]>` `set-speed <value[0..100]>` (unsafe) `Zset-speed <value[0..100]>` `get-speed` `get-dir` `get-motor` `config-acc-rate <value[0..100]>` `config-brak-rate <value[0..100]>` `config-acc-rate-delay <value[0..0xFFFF]ms>` `config-brak-rate-delay <value[0..0xFFFF]ms>`
`motors`	control motors of pluto-pico at once pluto-pico version: >= v0.4.0	`set <speed_m1[0..100]> <dir_m1[0\|\|1]> <speed_m2[0..100]> <dir_m2[0\|\|1]>`

Developing Pluto_pico

Pluto_pico is based on zephyr. Please refer to the repo here: https://gitlab.com/pluto_ipek/pluto_pico

To start please refer to the Installation of zephyr. https://docs.zephyrproject.org/latest/develop/getting_started/index.html

It is necessary to install any dependencies, zephyr and the zephyr sdk. We highly recommend to test zephyr and get some understanding by building the blinky example. Following the zephyr tutorial the blinky example for the raspberry_pico can be built via:

west build -p always -b rpi_pico samples\basic\blinky

External pin mapping on the Pico W is identical to the Pico, but note that internal RP2040 GPIO lines 23, 24, 25, and 29 are routed to the Infineon module on the W. Since GPIO 25 is routed to the on-board LED on the Pico, but to the Infineon module on the Pico W, the “blinky” sample program does not work on the W (use hello_world for a simple test program instead). For more information about the Raspberry Pico in zephyr please visit: https://docs.zephyrproject.org/latest/boards/arm/rpi_pico/doc/index.html

After the installation is complete and verified the project can be cloned locally.

When opening the project with an IDE such as CLion the IDE will ask for the CMake target. Chose Build Type Default and leave everything else as it is. The application will find zephyr and any dependencies on its own.

After the CMake build has finished several targets are available to build. The default target “zephy_final” will build the pico application. The relevant binary for the raspberry_pico will be the zephyr.uf2.

Relays of Pluto_pico

Pluto_pico is able to control 8 relays such as from: https://www.az-delivery.de/products/8-relais-modul.

It is important that the jumper is set from VCC to JD-VCC!

Each relay has one NC-contact(normally-closed contact) and one NO-(normally-closed contact).

If the relay is OFF the NC-contact is closed and the NO-contact will be open.
If the relay is ON the NC-contact is open and the NO-contact is closed
At startup each relay is set to OFF!

Relays that are ON will trigger a bright red led. Before startup the leds will have a weak red led. This is due to the Optokopplers in that relay module. The relays are still OFF in that state! After startup the leds will signal the correct relay state.

Pin assignment:

GPIO Assignments and Relay Names
Raspberry Pi Pico Pin	Relay Module Pin	Relay Name
GND	GND
VBUS	VCC
GPIO9	IN_1	relay_0
GPIO8	IN_2	relay_1
GPIO7	IN_3	relay_2
GPIO6	IN_4	relay_3
GPIO5	IN_5	relay_4
GPIO4	IN_6	relay_5
GPIO3	IN_7	relay_6
GPIO2	IN_8	relay_7

Usage:

relays -–set-bytes <value>
Set relays via a bit mask. Value in decimal from 0..255.

Examples for values:
- 0: all relays OFF
- 5: relais_2 and relais_0 ON, others OFF
- 255: all relays ON
relays –get-relay <name>
Gets the state of the relay <name>. State can be 0 (OFF) or 1 (ON).

<name> can be found by calling relays -list-relays
relays -–set-relay <name> <state>
Set relay by name to specific state. State can be 0 (OFF) or 1 (ON).

<name> can be found by calling relays -list-relays
relays -–list-relays
show all relay names

Examples:

Showing the GPIO signals of the raspberry pico by switching relay_0.

Notice that the optocoppler are LOW_ACTIVE!

Motors of Pluto_pico

The Motor Control Module, as part of the larger pico-pluto project, offers comprehensive functionality for controlling motor drivers in embedded systems. This module is critical for applications such as robotics and automation, where precise motor control is essential.

Features

Control of motor speed and direction using PWM and GPIO.
Ability to query the current state of motors.
Integration of a command-line interface for motor control.
Initialization and configuration capabilities for motor control hardware.

Pluto_pico is able to control 2 DC motors using the following motorshield MDD10A: https://www.cytron.io/p-10amp-5v-30v-dc-motor-driver-2-channels.

Also other motorshields could be used just notice that the pwm frequency is set to 20kHz.

Each motor has one PWM and one DIR contact.

motors can be controlled either individually using the commands motor1 or motor2 or at once using the motors command.

Pin assignment:

GPIO Assignments and MDD10A Names
Raspberry Pi Pico Pin	MDD10A	motor name
GND	GND
GPIO11	DIR1	motor_1
GPIO12	DIR2	motor_1
GPIO14	PWM1	motor_2
GPIO15	PWM2	motor_2
NC	B+ (5V to 30VDC)
NC	B-

Usage:

motorX stands for either motor1 or motor2 Command motorX Zset-speed <0-100> skipped since it is not recommended to use.

motorX set-dir <0/1>
Sets the direction of motorX. 0 for one direction, 1 for the opposite direction.
motorX set-speed <0-100>
Sets the speed of motorX. Specify the speed as a percentage of the maximum speed (0 to 100).
motorX get-speed
Retrieves the current speed of motorX. Returns the speed as a percentage of the maximum speed.
motorX get-dir
Retrieves the current direction of motorX. Returns the direction as 0 (one direction) or 1 (opposite direction).
motorX get-motor
Retrieves the current configuration and status of motorX. Outputs details like speed, direction, acceleration rate, braking rate, etc.
motorX config-acc-rate <0-100>
Configures the acceleration rate of motorX. Specify the rate as a percentage (1 to 99).
motorX config-brak-rate <0-100>
Configures the braking rate of motorX. Specify the rate as a percentage (1 to 99).
motorX config-acc-rate-delay <ms>
Configures the acceleration rate delay of motorX. Specify the delay in milliseconds (1 to 0xFFFF).
motorX config-brak-rate-delay <ms>
Configures the braking rate delay of motorX. Specify the delay in milliseconds (1 to 0xFFFF).
motors set <speed_motor1> <dir_motor1> <speed_motor2> <dir_motor2>
Sets the speed (0-100) and direction (0/1) for both motor1 and motor2 simultaneously. Provide each motor’s speed and direction as separate arguments.