Cheatsheet

A dense quick reference distilled from Vols 1 to 8. Nothing new is introduced here. Facts are marked C where a vendor or repository source states them directly, U where they rest on a single secondary source, and NF where no reachable source establishes them.

9.1 The four machines

Table 1 — The four machines

	Bittle	Nybble	Bittle X V2	Nybble Q
Animal	dog	cat	dog	cat
Joints	9	11	9	11
Board	NyBoard V1	NyBoard V1	BiBoard V1	BiBoard V1
Processor	ATmega328P	ATmega328PA	ESP32-WROOM-32D	ESP32-WROOM-32D
Size (mm)	200x110x110	250x107x140	190x153x107	240x115x150
Mass	265–290 g	320 g	269–353 g	403–433 g
Frame	plastic	wood	plastic	3D-printed
Radio	dongle	dongle	Wi-Fi + BT	Wi-Fi + BT
Voice	no	no	yes	yes
Feedback servos	no	no	yes	yes
Price	USD 289 / 309	USD 299	USD 319	USD 435
Status	final stock	sold out	current	current

Joint breakdown: dog = 4 legs x 2 + 1 neck. Cat = 4 legs x 2 + 2 head + 1 tail. Arm variant: Bittle X V2+Arm replaces the head with a 2-DOF arm and gripper → 10 joints.

9.2 Boards

Table 2 — Boards

	NyBoard V1	BiBoard V1
Processor	ATmega328P, Arduino Uno class	ESP32-WROOM-32D, dual core 240 MHz
SRAM	—	520 KB
Flash	—	4 MB vs 16 MB — conflict, see below
EEPROM	64 Kbit	64 Kbit
IMU	MPU6050	MPU6050 or ICM42670, per chip availability
PWM	16	12
Grove	4	—
Built-in	UART, I2C, IR receiver, buzzer	UART, I2C, speaker, BT, Wi-Fi
Repository	PetoiCamp/OpenCat	PetoiCamp/OpenCatEsp32-Quadruped-Robot

Flash conflict (C, unresolved): the Bittle X specification page says 16 MB; the Nybble Q page says 4 MB; the ESP32 firmware README’s upload settings specify a 4 MB partition scheme. Weight of evidence favours 4 MB. Read the partition table off the board rather than trusting either page.

9.3 Servos and power

Table 3 — Servos and power

Item	Value	Conf.
Models	P1S alloy, P1L lite plastic, coreless	C
Max voltage	8.4 V	C
Legacy Nybble	DS031 metal, 11 fitted	C
Pack quantity	10 (dog), 12 (cat) — extras are spares	C
Torque / speed ratings	not published	NF
Battery	7.4 V 1000 mAh Li-ion	C
Current	~2 A typical, 5 A peak	U
Runtime	~1 hour continuous walking	C
Charge	1.5 h (BiBoard), 2 h (NyBoard)	C
Charger	USB 5 V 1 A; not included with legacy Nybble	C
Payload	~1 lb	U

9.4 Motion and voice

• More than 35 movements and skills: walk, trot, run, crawl, balance, sit, stretch, sleep, greet, push-up.
• Bittle backflips; Nybble does not — mass, not software. The framework supports it.
• Balance loop reads the 6-axis IMU and corrects leg positions continuously.
• Gait tables are precomputed; runtime work is interpolation. This is what fits the framework onto an ATmega328P.
• Voice: 35+ built-in commands, 10 user-defined, English and Chinese switchable by voice, any sound can trigger, processed entirely on the robot. No server, no account.
• Feedback servos enable teaching by demonstration and mirroring.

9.5 Programming

Table 4 — Programming

Route	Open?	Needs vendor software?
Petoi Coding Blocks (desktop and web)	—	yes, the environment
Arduino IDE, C++	MIT source	no
Python API	MIT source	no
Mobile app	proprietary	yes

The Python API is inside the firmware repository at serialMaster/. There is no separate OpenCatPythonAPI repository — that name 404s.

Table 5 — Programming

Module	Role
ardSerial.py	serial communication core
robot.py	wrapper, published as PetoiRobot

Key functions: autoConnect(), openPort(), closePort(), sendSkillStr(), rotateJoints(), play(), readAnalogValue(), writeDigitalValue().

9.5.1 Token protocol

Table 6 — Token protocol

Token	Meaning
k	skill shortcut — ksit, kup, kbalance
K	real-time skill data
m / M	joint rotation, sequential — ASCII / binary
i / I	joint rotation, simultaneous — ASCII / binary
b	buzzer

Lower case takes ASCII, upper case takes binary. Examples:

sendSkillStr('ksit', 3)
rotateJoints('M', absValList(0, 60), 1)

Typed straight into a serial terminal, no library required:

kbalance
m 0 -30 0 30

Gotcha: no Bluetooth response often means bluetoothPortIndex in ardSerial.py (around line 128) is selecting the wrong port.

9.5.2 Firmware upload, BiBoard

921600 baud · 240 MHz CPU · QIO flash mode · 4 MB partition scheme · Arduino IDE.

9.6 Origin and company

Table 7 — Origin and company

Date	Event
2016	OpenCat begun by Dr. Rongzhong Li at Wake Forest University
2017	Petoi founded
2018	Nybble on Indiegogo — USD 136,536 from 580 backers
Oct 2020	Bittle on Kickstarter — USD 567,000 from 2,052 backers
—	30,000+ robots shipped to 60+ countries
2 Sep 2026	Quaddle Kickstarter launches — outside this dive’s scope

Both firmware repositories were still receiving commits in September 2026. Licence: MIT, both.

9.7 Buying checklist

Verify current prices — they move with tariffs. Choose alloy (P1S) servos for durability, lite (P1L) for cost. Nybble Q is pre-assembled only at present. Used legacy units are a sound buy because the NyBoard firmware is still maintained; check every servo drives and holds, the frame is uncracked, the battery holds charge, and a charger is included.

9.8 Open items

• servo torque and speed ratings — unpublished, so payload cannot be derived
• BiBoard flash capacity — vendor pages conflict
• battery cycle life and replacement availability
• measured gait stability and servo durability — no independent measurement located
• the specific research literature named in this subproject’s scaffolding, not retrieved
• camera module part numbers and co-processor wiring detail

9.9 Hub contrast, one row

Table 8 — Hub contrast, one row

	Petoi Bittle / Nybble	Anki Cozmo / Vector
Kept alive by	an MIT-licensed firmware repository the owner already has a copy of	architecture (Cozmo) or a community server replacing a dead cloud (Vector)

Fuller cross-robot matrix: _shared/comparison.md.

Sources

This cheatsheet introduces no new claims; every row traces to Vols 1 to 8 and through them to the sources cited there. Principal anchors: petoi.com technical specification and product pages; guide.petoi.com and docs.petoi.com; the PetoiCamp/OpenCat and PetoiCamp/OpenCatEsp32-Quadruped-Robot repositories and their metadata; learnwitharobot.com; and tvgreport.com.