We built a horse-riding machine controller using the 3.5-inch RP2350 touch LCD.

  • 12 operating modes: one manual mode and 11 program modes
  • 10-stage speed graph: speed levels 1-10 for each stage
  • 6-60 Hz inverter control: converts each speed level to a frequency
  • RS485 Modbus RTU: START, STOP, and speed commands with operating-status checks
  • RP2350 dual core: separates motor communication from touch-screen processing
  • 480×320 ST7796 LCD: running-horse animation with partial screen updates

Setting the operating mode and ride time on the RP2350 touch LCD

RP2350 horse-riding machine controller specifications

ItemSpecification
MCURP2350 dual core
Display3.5-inch ST7796, 480×320
TouchFT6336U capacitive touch
Operating modesM01-M12
Manual modeM01
Program modesM02-M12, 11 total
Program stages10 stages per mode
User speedLV01-LV10
Inverter frequency6-60 Hz
CommunicationRS485 Modbus RTU, 19,200 bps, 8N1
Screen processingOne RGB565 back buffer with changed-region transfers

RP2350 horse-riding machine touch LCD showing manual mode M01 and speed LV01

M01 manual mode: change speed directly from 1 to 10

M01 is the manual operating mode. The S- and S+ buttons on the home screen change the speed through levels 1-10.

Screen speedInverter command
LV016 Hz
LV0530 Hz
LV1060 Hz

The user selects only LV01-LV10 on screen, and the RP2350 converts that value to a 6-60 Hz frequency and sends it to the inverter.

M02-M12 program modes: automatic speed changes over 10 stages

M02-M12 are program operating modes. Each mode has 10 speed stages.

total ride time ÷ 10 = operating time per stage

Example: 10-minute ride
→ 1 minute per stage
→ apply the next speed every minute

Running a program mode on the RP2350 touch LCD horse-riding machine controller

Connecting the RP2350 touch LCD, inverter, and motor

RP2350 touch LCD connected to an RS485 module and inverter motor

RS485 transceiver that converts the voltage and signaling between UART and RS485

RS485 terminal wiring on the inverter in the horse-riding machine control system

The RP2350’s 3.3 V UART must not be connected directly to the inverter’s A/B terminals. An RS485 transceiver is required between UART and RS485 to convert the voltage and signaling method.

The seven-step process after START

  1. Confirm the START input on the touch screen.
  2. Confirm that the inverter is stopped.
  3. Write the selected speed to the S05 frequency command.
  4. Read S05 back and confirm that the value was applied.
  5. Write the FWD run command to S06.
  6. Check the operating status and actual frequency every 500 ms.
  7. Change the screen to RUNNING after operation is confirmed.

The maximum response wait for one Modbus request is 200 ms. If the operating state and actual frequency are not confirmed within 10 seconds after START, the controller sends STOP. The controller also sends STOP when status polling fails three times in a row.

Testing horse-riding machine control with the RP2350 touch LCD, inverter, and motor connected

RS485 processing and touch LCD processing

The RS485 implementation exchanges only the START, STOP, mode, and speed commands with the touch LCD implementation. Even during the maximum 200 ms wait for an inverter response, the touch LCD implementation continues handling touch input and screen processing.

Horse-riding machine control setup connected through an RS485 transceiver to the inverter and motor

Reducing screen flicker with a 307,200-byte back buffer

The size of one 480×320 RGB565 screen is:

480 × 320 × 2 bytes = 307,200 bytes

Instead of using two screen buffers, we used one 307,200-byte back buffer. When a button, the time, the graph, or a horse frame changes, only that rectangular region is transferred to the ST7796.

The horse animation consists of three PNG frames. Before compositing the next frame, the controller restores the background where the previous horse was displayed, so no black rectangle remains.

The implementation details are covered in RP2350 TFT LCD animation and ST7796 partial screen updates.

A communication STOP is not an emergency stop

S06 STOP is a Modbus communication command. It does not cut power, and it cannot stop every fault involving a broken communication line, an RP2350 failure, or an inverter failure.

A horse-riding machine carrying a person requires separate devices for:

  • A hardware emergency-stop switch
  • A motor power cutoff circuit
  • Mechanical position and limit interlocks
  • Rider departure and overload detection
  • Stopping-distance tests under actual equipment conditions

Summary

The six core elements of this horse-riding machine controller are:

  1. RP2350 Touch LCD 3.5
  2. One manual mode and 11 program modes
  3. A 10-stage speed profile for each mode
  4. Conversion of speed levels 1-10 to 6-60 Hz
  5. RS485 Modbus inverter START, STOP, and status checks
  6. Core 0 for communication and Core 1 for the screen

When a horse-riding machine, rehabilitation device, or riding simulator needs mode, time, speed, and inverter control, the touch UI and RS485 communication can be configured together for the equipment specifications.

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