Zombo

Zombo the Robot

Microcontroller

Zombo runs on an Adafruit ESP32-S3 Feather. We chose this because it is a powerful microcontroller with WI-FI and Bluetooth radios so that we have some flexibility for features and communications later. It supports several serial protocols and has a flexible GPIO system, but it will primarily communicate with most peripherals over an I2C bus. This is a widely used protocol and simplifies the interface to the peripherals.

Sub-Systems

Zombo is composed of the following subsystems.

1. Display - Provides command feedback and status
2. Command - Uses voice recognition to accept command inputs.
3. Navigation - Uses ultra-sonic distance sensor for collision avoidance.
4. Motors - Two drive wheels and one caster provide locomotion.
5. Command - Uses voice recognition to accept command inputs.
6. LED - It's not a robot without LEDs. We wil use the addressable NeoPixels.
7. Diagnostics - Monitor Robot health including battery monitor and wireless signal strength
8. Power - Power will be supplied with a battery. There are several voltage requirements. The microcontroller Feather and the Feather Wings runs on 3.3 VDC, The motors run on 4-6 VDC, and the LEDs use 5 VDC.

I2C Buses

Bold addresses are non-default.

Since the ultrasonic sensor doesn't play nice on the I2C bus¹ it will get it's own dedicated bus.

Device	Bus	Address	Available Range	Sub-system
OLED Display FeatherWing	Main	0x3C	0x3C-0x3D	Display
DC Motor + Stepper FeatherWing	Main	0x61	0x60-0x7F	Motors
NeoDriver	Main	0x60	0x60-0x67	LED
Voice Recognition	Main	0x64	Fixed	Command
Ultrasonic Distance Sensor	Distance	0x57	Fixed	Navigation
Feather ESP32-S3 onboard batter moniotor	Main	0x36	Fixed	Diagnostics

Development Setup

Setup Python virtual environment

python -m venv venv
. venv/bin/activate

Install Python modules

pip install -r requirements.txt

Install CircuitPython modules

circup install -r circuitpython-requirements.txt

Note: circup downloads and stores copies of the packages in ~/.local/share/circup/ or whatever the output of python -m site --user-base returns.

Serial Console

screen /dev/ttyACM0 115200

Footnotes

1. We noticed that while this sensor does work with I2C it's not very 'friendly' - it doesn't like to share the I2C bus, we think it gets confused by other commands and can lock up the bus.

   -Adafruit RCWL-1601 Product Description

   ↩