BIGTREETECH TMC2225 V1.0 – Silent UART / STEP-DIR stepper motor driver

BIGTREETECH TMC2225 V1.0 is a silent driver for two-phase bipolar stepper motors. It can operate through STEP/DIR signals or a single-wire UART connection. It includes StealthChop2 for quieter movement, SpreadCycle for more dynamic operation and MicroPlyer interpolation up to 256 microsteps.

Its plug-in format allows it to be used with many boards equipped with StepStick or Pololu-type sockets. Compatibility must always be checked against the pinout, orientation, logic voltage, motor supply, configuration jumpers and available space for the heatsink.

Main features

• BIGTREETECH TMC2225 driver, revision V1.0.
• STEP/DIR or single-wire UART control.
• StealthChop2 for quiet operation.
• SpreadCycle for a more dynamic response and improved torque capability in some applications.
• Hardware selection of 4, 8, 16 or 32 microsteps.
• Internal MicroPlyer interpolation up to 256 microsteps.
• Firmware control of current, microsteps and operating mode when using UART.
• Configurable standstill-current reduction.
• Integrated protection and diagnostic functions.
• 0.15 Ω external sense resistors.
• Compact 15.24 × 20.32 mm format, excluding pins and heatsink height.

STEP/DIR operation

In autonomous or standalone mode, the mainboard controls movement through the STEP and DIR signals. Motor current is adjusted with the potentiometer and microsteps are selected through MS1 and MS2.

SPREAD left open or connected to GND selects StealthChop. Connecting SPREAD to VCC_IO selects SpreadCycle. The method used to establish these levels depends on the mainboard jumpers and connections.

UART operation

UART communication allows the firmware to configure motor current, microsteps, standstill-current reduction and StealthChop or SpreadCycle operation. The mainboard must provide a compatible UART connection and be configured for this driver.

R3 supports several preparations:

• Factory configuration: R3 open, with one UART pad and one unconnected pad.
• 0 Ω bridge: both pads are connected to the single-wire UART line.
• 1 kΩ resistor: separates RX and TX according to the manufacturer's diagram.

Do not modify R3 without checking the mainboard UART circuit. Some controller boards already provide the required connection or series resistor.

Pinout and compatibility

The module uses the compact two-row format commonly found on plug-in stepper drivers. It can operate in compatible sockets used by RepRap systems, Prusa i3 derivatives, CoreXY printers, CNC machines and other custom equipment, but a similar-looking socket does not guarantee compatibility.

Before installation, check:

• The positions of VM, GND, VIO, EN, STEP and DIR.
• The A1, A2, B1 and B2 motor-output order.
• The logic voltage used by the mainboard.
• The motor supply and system electrical limits.
• The MS1/MS2 and UART jumper configuration.
• The physical orientation and available heatsink clearance.

Subject to board revision and jumper verification, it may be compatible with boards accepting plug-in TMC2208 drivers, including certain RAMPS, MKS Gen L, BIGTREETECH SKR and similar controllers. UART compatibility depends on the exact mainboard and its configuration files.

Important: the TMC2225 does not include StallGuard. It is not a direct replacement for a TMC2209, TMC2130 or TMC5160 when sensorless homing is required. Many Voron configurations use StallGuard-capable drivers; this module is only suitable when physical endstops are used and the electronics are otherwise compatible.

Marlin configuration

Marlin specifies that the TMC2225 should be declared as a TMC2208. For UART operation, configure the relevant axis as follows:

#define X_DRIVER_TYPE TMC2208

For standalone operation without UART communication:

#define X_DRIVER_TYPE TMC2208_STANDALONE

Replace X with the required axis. UART operation also requires the correct serial pins, RMS current and microstep settings in the appropriate sections of Configuration.h, Configuration_adv.h and the mainboard pin file.

• This module uses 0.15 Ω sense resistors.
• Current must be selected for the particular motor, mechanics and cooling arrangement.
• The 800 mA shown in the manufacturer's manual is an example, not a universal recommendation.
• M122 can be used to check communication and read diagnostics when UART is operating correctly.

Klipper configuration

BIGTREETECH documents the TMC2225 as compatible with TMC2208 control. A UART configuration can use the following structure:

[tmc2208 stepper_x]
uart_pin: <mainboard UART pin>
run_current: <suitable motor RMS current>
sense_resistor: 0.150
interpolate: True

The axis name and UART pin must be obtained from the mainboard schematic and configuration file. Klipper uses SpreadCycle by default. To use StealthChop throughout the speed range, the following setting can be added:

stealthchop_threshold: 999999

SpreadCycle generally provides greater torque and positional accuracy, while StealthChop may reduce audible noise. Select the mode according to the axis, speed and mechanical load.

In standalone mode, no [tmc2208] section is added. The microstep setting in the stepper section must match the hardware selection made through MS1 and MS2.

RepRapFirmware configuration

On a compatible board, the module can be used as a conventional STEP/DIR driver. Microsteps, steps per millimetre, current and direction must be set according to the electronics, motor and physical axis configuration.

There is no universal RepRapFirmware UART configuration for this plug-in module. UART control should only be attempted when the specific board and firmware version explicitly document a compatible external TMC2208/TMC2225 interface. Otherwise, use STEP/DIR operation.

Current adjustment and cooling

The 2 A limit refers to the IC peak-coil current and is not a continuous recommendation for every installation. Trinamic uses 1.2 A RMS per coil as a continuous design guideline and reserves 1.4 A RMS for short periods under controlled thermal conditions.

Available current depends on airflow, voltage, motor, enclosure temperature and the space surrounding the controller board. Always install the heatsink and provide active airflow when required by the current or operating temperature.

For manual adjustment:

• Turning the potentiometer clockwise reduces VREF and motor current.
• Turning the potentiometer counter-clockwise increases VREF and motor current.
• The manufacturer recommends measuring VREF while the mainboard is powered from 12 or 24 V.
• Do not force or continuously rotate the potentiometer.
• Begin with a conservative current and check temperature, torque and missed steps.

Safe installation

1. Completely disconnect both power and USB from the controller board.
2. Check the pinout and locate VM, GND, EN and DIR on both the module and mainboard.
3. Configure the required STEP/DIR or UART jumpers.
4. Insert the driver in the correct orientation. Reversing it can immediately damage the driver and mainboard.
5. Install the heatsink without creating electrical contact with nearby pins or components.
6. Connect the two motor coils according to A1/A2 and B1/B2.
7. Set a conservative initial current and test movement at low speed.
8. Check the driver temperature during an extended test and increase cooling or reduce current if required.

Never connect or disconnect the motor while the electronics are powered. Induced voltage and intermittent contacts can destroy the driver.

When should another driver be selected?

The TMC2225 is a suitable option when quiet operation, UART and a compact format are required without sensorless homing. If the machine requires StallGuard or a newer alternative for that type of installation, consider the BIGTREETECH TMC2209 UART / STEP-DIR, while still checking board revision, pinout and compatibility.

Contents

• 1 BIGTREETECH TMC2225 V1.0 driver.
• 1 heatsink.

Further technical documentation is available from the official BIGTREETECH repository.