A general-purpose ESP32 remote control for small robots. It is not tied to any one machine: the link carries a fixed set of controls, and the robot at the other end decides what they mean and what the screen shows. A hexapod is the first thing it was built to drive; adding another robot is a change to that robot's firmware, not to this one.
It comes in two variants, with one or two joysticks. Which one is running is a menu setting stored on the device, and is announced to the robot when the link comes up.
| One joystick | Two joysticks |
|---|---|
 |
 |
Sends controls 20 times a second — two 3-axis joysticks at ±1000 per axis, their two buttons, four switches, and the transmitter's own tilt on two axes from the IMU.
Takes its screen contents from the robot. The robot sends back a name, a device id (the
transmitter presents an icon based on that information), a caption for each switch and button,
and up to four label/value pairs. So a hexapod can label a switch Gait and display
height= 13.4 without this firmware knowing anything about hexapods.
Pairs by itself. The robot broadcasts, the transmitter answers, and from then on each end accepts frames only from the other. One peer at a time, dropped after a second of silence and re-paired without user action. Both ends check a protocol version on every frame, so a robot flashed from a different revision of the wire format reports a clear mismatch instead of misreading values.
Shows battery charge, the paired robot's name and icon, live joystick positions, switch states with their labels, IMU tilt, temperature, and an optional frame counter.
Offers a menu for joystick calibration (centre and end stops per axis, stored in flash), IMU calibration, one- or two-joystick selection, sound volume, frame-rate display, and a full reset.
Makes noise through an I2S amplifier — a click on every switch, a beep on button presses, a sound at start-up.
- ESP32-WROOM-32E (Board package esp32 3.3.11)
- 480x320 TFT Display (ST7796 3.5)
- MPU6050 IMU
software/ |
The Arduino sketch and its TFT_eSPI configuration |
hardware/ |
PCB: EasyEDA project, Gerbers, schematic, bill of materials |
mechanics/ |
Housing: Fusion source, STLs, print profiles |
docs/ |
Photographs, wiring notes, display-image sources |
software/Transmitter/RCProtocol.h is the master copy of the wire format. It describes what
this transmitter can send and what it can display, so its shape follows this hardware rather
than any one robot's needs - which is why it lives here and not in the robot.
Every robot driven by this transmitter carries a copy of that file, because Arduino cannot
include across sketch folders. Edit it here, then copy the result to each robot.
cAppProtocolVersion is the guard: both ends check it on every frame, so a copy that has
fallen behind shows up as a logged mismatch at pairing rather than as silently misread data.
The robot announces itself with an EDeviceType, which is how the transmitter picks the icon
to show for it:
| Robot | EDeviceType |
|---|---|
| Hexapod | eHexapod |
- Install the required libraries (see Dependencies below).
- Open
software/Transmitter/Transmitter.inoin the Arduino IDE. - Select board ESP32 Dev Module with 8 MB flash.
- Partition Scheme: "Custom"
- Upload.
The partition scheme software/Transmitter/partitions.csv sits in the
sketch folder, and the ESP32 core uses it: a 6 MB application partition plus a 1.9 MB LittleFS
partition. Nothing in the firmware writes to that filesystem today — calibration and settings
live in NVS — so there is nothing to upload to it, but the space is reserved.
The display needs no setting up: software/Transmitter/build_opt.h configures TFT_eSPI as part of
the build. See software/Config/TFT_eSPI if you would rather
configure the library the conventional way, or if you are not using the ESP32 Arduino core.
Versions are the ones this project is built and tested against.
Bundled with the ESP32 board package - nothing to install: WiFi, Networking, Wire,
SPI, Preferences, and the ESP-IDF driver/i2s_std.h audio API that SoundEngine sits on.
From the Arduino Library Manager - all of them, including the two written for this project:
| Library | Version | Note |
|---|---|---|
| Streaming | 6.3.0 | |
| TFT_eSPI | 2.5.43 | by Bodmer - configured by build_opt.h, see above |
| Bounce2 | 2.71 | |
| MPU6050_light | 1.2.1 | by rfetick - several MPU6050 libraries exist, this is the one used here |
| Adafruit MAX1704X | 1.0.3 | |
| Adafruit BusIO | 1.17.4 | dependency of MAX1704X |
| ESPNowUtilities | 1.0.0 | the ESP-NOW transport RCProtocol.h is built on |
| SoundEngine | 1.0.0 | SoundEngine.h and the sounds/ clips |
This project is licensed under the MIT License – see the LICENSE file for details.