Smoothieboard V2 vs V1 - Complete Comparison

This comprehensive guide documents all the differences between Smoothieboard V2 and V1, including hardware specifications, firmware architecture, configuration changes, and migration considerations.

Target Audience: Users migrating from V1 to V2, developers porting code, and anyone evaluating which version to choose. For basic V2 specifications, see Smoothieboard V2 Prime. Smoothieboard V2 Prime

Quick Comparison

Feature V1 (LPC1769) V2 (STM32H745) Improvement
CPU Clock 120 MHz 480 MHz 4x faster
Flash 512 KB 2 MB 4x more
RAM 64 KB 1 MB 16x more
Step Rate 100 kHz 200 kHz 2x faster
Microstepping 1/32 1/256 8x finer
SD Card Speed 0.4-0.5 MB/s 10-25 MB/s 20-50x faster
Stepper Drivers A5984 (basic) TMC2660/2590 (SpreadCycle) SPI-configurable drivers
Expansion GPIO Limited 90 pins (Gadgeteer) Extensive
Price $100-150 $230 Higher

1. Hardware Platform

1.1 Microcontroller Comparison

Major Upgrade: The STM32H745 is a significantly more powerful processor, enabling faster motion, more features, and better multitasking through its RTOS-based architecture.

V1: NXP LPC1769

Specification Value
Core ARM Cortex-M3
Clock 100-120 MHz
Flash 512 KB
RAM 64 KB (32 KB local + 32 KB AHB SRAM)
FPU None (software emulation)
Cache None

V2: STM32H745

Specification Value
Core Dual-core: Cortex-M7 (480MHz) + Cortex-M4 (240MHz)
Flash 2 MB
RAM 1 MB total (DTCM: 128KB, ITCM: 128KB, AXI SRAM: 512KB, SRAM1-4: 352KB)
FPU Double-precision (M7), single-precision (M4)
Cache 16KB I-cache + 16KB D-cache
Package 265-pin BGA
M4 Core Status: The M4 core is currently unused/disabled in firmware (configured to sleep on boot). Enabling dual-core operation requires considerable development work. Potential future uses include UI, networking, or data logging.

1.2 Board Variants

V2 Prime (In Production):

  • STM32H745 dual-core processor
  • 4x TMC2660 or TMC2590 stepper drivers
  • 9x Gadgeteer expansion headers (90 pins)
  • Ethernet (10/100 Mbps)
  • Dual USB (Device + Host)
  • SDIO SD card interface
  • Price: $230 USD
  • OSHWA certified: FR000021

V2 Mini (Development Postponed):

  • Lower-cost variant, not currently available
  • COVID and tariffs delayed development

V2 Pro (Cancelled):

  • Was planned to include FPGA for megahertz step rates
  • Cancelled with the LPC4330 redesign

1.3 Physical Specifications

Dimension V1 V2
Length 129 mm ~140-150 mm
Width 105 mm ~120-130 mm
Mounting 4 corner M3 holes 4 corner M3 holes

2. Stepper Motor Drivers

2.1 Driver Comparison

This comparison covers the P11 Prime2660 and P12 Prime2590 designs, whose driver schematics specify TMC2660 and TMC2590 respectively. Both chips provide SpreadCycle, StallGuard2 and CoolStep, but neither provides StealthChop2 or StallGuard4. See the revision-qualified Prime specifications and firmware notes and the manufacturer documentation for TMC2660 and TMC2590. These capabilities should not be generalized to other V2 revisions or external drivers.

SpreadCycle Operation: The Prime TMC2660/2590 drivers use SpreadCycle current control. Acoustic behavior depends on the motor, current, speed and chopper configuration; these chips do not provide StealthChop2 or a near-silent-operation guarantee.
Feature V1 (A5984) V2 (TMC2660/2590)
Count 3-5x 4x
Max Current 2A 2.8A (2660) / 5.0A (2590)
Microstepping Up to 1/32 Up to 1/256
Silent Mode No No StealthChop2; SpreadCycle current control
Sensorless Homing No StallGuard2 load detection; homing requires firmware configuration, tuning and validation
Dynamic Current No CoolStep capability; disabled by default in the reviewed firmware drivers
Interface Digital pot (I2C) SPI configuration

2.2 TMC2660 vs TMC2590

Specification TMC2660 TMC2590
Ideal Current 1.2-2.2A 2.5-4.6A
Best For 3D printers (NEMA 17) CNC (NEMA 23/24)
Thermal Lower heat, passive cooling OK Higher heat, may need fan
Board ID 1 0

2.3 Configuration Changes

V1 Motor Configuration:

alpha_steps_per_mm 100
alpha_step_pin 2.0
alpha_dir_pin 0.5
alpha_en_pin 0.4
alpha_current 1.5
alpha_max_rate 30000.0

V2 Motor Configuration:

[actuator]
alpha.steps_per_mm = 100
alpha.step_pin = PG0
alpha.dir_pin = PG1
alpha.en_pin = PJ2
alpha.max_rate = 30000
alpha.microsteps = 32
alpha.driver = tmc2660

[tmc2660]
alpha.current = 1500  # mA (not A like v1)
alpha.step_interpolation = false

Key changes:

  • Setting names use dots:
  • Pin names changed: 2.0 (v1) vs PG0 (v2)
  • Current in milliamps (v2) vs amps (v1)
  • INI sections replace flat config

3. Power System

3.1 Power Architecture

Dual Power Design: V2 separates motor power (Vmot) from MOSFET power (VFET), providing better isolation and current handling.
Input V1 V2
Motor Power Single input, 12-24V Vmot via XT30, 12-24V
MOSFET Power Shared with motor VFET via 2x XT30, 12-24V (30A total)
Logic 5V Regulator or USB 3 sources with ideal diode OR
5V Regulator Optional (solder on) Onboard 3A

V2 5V Power Sources (automatic selection):

  1. Onboard Regulator: 3A from Vmot (JP16 to disable)
  2. USB Power: ~500mA (JP15 to disable)
  3. External 5V: Via 5VIN header

3.2 MOSFET Outputs

Output V1 V2
Low-current FETs 3x ~5A 4x ~5A (hotend1, hotend2, fan1, fan2)
Bed FET 3x ~12A 2x parallel ~10-12A
Safety None High-side PFET watchdog on 4 low-current FETs
SSR Outputs None 2x logic-level outputs
Thermal Runaway Protection: V2's high-side PFET can instantly kill all 4 low-current outputs. If a MOSFET fails shorted, the watchdog can still disconnect power - a significant safety improvement over V1.

4. Inputs and Expansion

4.1 ADC Inputs (Thermistors)

Feature V1 V2
ADC Resolution 12-bit 16-bit (oversampled)
Buffered Inputs Basic 3x with ESD protection + op-amp buffer
Unbuffered - 6x on Gadgeteer headers
Board Thermistor No Yes (PCB temperature monitoring)
Voltage Monitoring No Yes (Vmot, Vfet, Vbat via ADC3)

4.2 Endstops

Feature V1 V2
Count 6 (X/Y/Z min/max) 6 (X/Y/Z min/max)
Protection Basic Buffered + ESD protected
Current Limiting No Yes (3.3V and 5V outputs)

4.3 Probe Input

CRITICAL WARNING: The JP7 jumper controls probe input voltage range. Default (JP7 intact) is for <5V operation. For probes >5V (like many inductive probes), you MUST cut JP7 or you will damage the board!
Feature V1 V2
Input Type Basic Comparator-based
Voltage Range ~5V 3-45V (configurable via JP7)
Protection Basic ESD + buffering + comparator

4.4 Gadgeteer Expansion Headers

V2 introduces 9 standardized Gadgeteer headers (GA through GI):

Per Header Value
Pins 10
GPIO 7
Power 5V + 3.3V + GND
Total GPIO 63 pins

Power Budget:

  • 5V: 3A total from onboard regulator
  • 3.3V: 100-500mA total

Use Cases:

  • Displays (LCD, touchscreens)
  • Additional thermistors (via daughterboard)
  • External stepper drivers
  • Sensors, Raspberry Pi, custom boards

5. Connectivity

5.1 Storage

SD Card Speed: This was the #1 user complaint about V1 - finally fixed! V2's SDIO interface is 20-50x faster than V1's SPI interface.
Feature V1 V2
Interface SPI SDIO
Speed 0.4-0.5 MB/s 10-25 MB/s
Max Capacity 32 GB SDHC 32 GB SDHC

5.2 USB

Feature V1 V2
Ports 1 (Device) 2 (Device + Host)
Speed 12 Mbps (Full Speed) 12 Mbps (Full Speed)
Functions CDC/ACM + MSC CDC/ACM + MSC (MTP planned)
Host Support No Hardware present, firmware WIP

5.3 Ethernet

Feature V1 V2
Speed 10/100 Mbps 10/100 Mbps
Stack uIP (lightweight) FreeRTOS+TCP (full-featured)
Throughput ~1 Mbps ~10 Mbps

V2 Network Services:

  • HTTP and WebSocket (port 80): static web files plus command and upload sockets
  • Network shell (port 23): G-code and console commands
  • FTP (port 21): unencrypted standard file transfer, not SFTP
  • Auto-Update: Network firmware update commands
  • NTP (outbound UDP port 123): real-time-clock synchronization

6. Firmware Architecture

6.1 Operating System

Feature V1 V2
Architecture Bare-metal superloop FreeRTOS multitasking
Concurrency Single-threaded Multi-threaded with task scheduling
Event System Global event bus Direct module communication
Step Ticker 100 kHz 200 kHz (50 kHz in debug)

RTOS Benefits:

  • Preemptive multitasking (predictable timing)
  • Network/USB don’t slow down motion
  • Stack overflow detection
  • Better memory management

6.2 Module System

V1: Event-based with broadcast model

class Module {
    virtual void on_main_loop(void *);
    virtual void on_gcode_received(void *);
    // ~9 events total
};

V2: Configuration-based with direct communication

class Module {
    Module(const char* group, const char* instance);
    virtual bool configure(ConfigReader& cr);
    virtual bool request(const char *key, void *value);
    static Module* lookup(const char *group, const char *instance);
};

6.3 Configuration Format

V1: Custom checksum-based key-value (flat file)

alpha_steps_per_mm 100
beta_steps_per_mm 100
default_feed_rate 4000

V2: Standard INI with sections

[motion control]
default_feed_rate = 4000
default_acceleration = 1000.0

[actuator]
alpha.steps_per_mm = 100
alpha.max_rate = 30000
Config Migration: V1 and V2 config files are NOT compatible. Manual conversion is required - there is no automatic migration tool.

7. Configuration Reference

7.1 Key Setting Mappings

Setting  
Steps/mm
Max rate
Acceleration
Junction deviation
Step pin
Motor current
Heater enable
PID P

7.2 V2 Configuration Sections

[general]
[system]
[motion control]
[planner]
[actuator]
[tmc2660] or [tmc2590]
[current control]
[endstops]
[zprobe]
[temperature control]
[extruder]
[switch]
[voltage monitor]
[network]

7.3 Pin Naming Changes

V1 pins: Port.Pin format (e.g., 2.0, 0.5)

V2 pins: PortPin format (e.g., PG0, PA5)

Pin modifiers (same concept, both versions):

  • ! - Invert
  • ^ - Pullup
  • v - Pulldown
  • o - Open-drain
  • - - No pull

Example: PG10^ (PG10 with pullup enabled)

8. Feature Status

8.1 Modules Ported from V1

Module Status Notes
Endstops Working Enhanced with slaved axis
Extruder Working  
Laser Working  
Temperature Control Working PID control
Temperature Switch Working Fan control
ZProbe Working Bed leveling
Switch Working I/O control
Kill Button Working  
Player Working G-code playback
Network Complete Rewrite Much more capable
Current Control Enhanced TMC SPI control
Filament Detector Working  
Drilling Cycles Working Renamed drillcycles

8.2 New in V2

Feature Description
Display Drivers ST7920, TM1638 support
Button Box Individual input switches, macros, and FAULT inputs. Matrix scanning remains unimplemented in the checked source
Lathe Module G33 threading and spindle synchronization
ELS Electronic Leadscrew controls with a TM1638; upstream notes label parts work in progress
MPG Direct per-axis control or one shared hand wheel selected with M922
Configurable Prime Drivers SpreadCycle current control and StallGuard2 load detection; no StealthChop2
OTA Updates Network firmware updates
Slaved Axes Software-parallel internal TMC motors and independent G28.7 alignment
Auxiliary UART target Send device messages with echo -1
NIST G30/G30.1 Stored machine position in GRBL mode
ed and le Streaming file editor plus interactive line editing and session history
O-word Subroutines Limited named subroutine definitions and calls
MAX7219 DRO X/Y/Z/A/B/C positions on seven-segment displays
Feed Hold Real-time ! hold and ~ cycle start; announced as work in progress

8.3 Not Yet Ported

  • SCARA calibration
  • Rotary Delta calibration
  • Some advanced features

9. When to Choose Each Version

Choose V2 If:

  • Need 200 kHz step rates (fast motion, fine microstepping)
  • Want SPI-configurable Prime stepper drivers with SpreadCycle current control and StallGuard2 load detection
  • Require extensive expansion (90 GPIO pins)
  • Need fast SD card access (large G-code files)
  • Want network features (web, telnet, OTA updates)
  • Building CNC lathe (G33 threading)
  • Future-proof investment
  • Budget allows $230

Choose V1 If:

  • Budget limited ($100-120)
  • Need mature, stable firmware
  • Prefer extensive documentation
  • Simple application (basic 3D printer)
  • Need 5 on-board drivers (V1 5X variant)
  • Want proven reliability

10. Troubleshooting Quick Reference

Board Won’t Power

  • Check Vmot power connected (12-24V to XT30)
  • Check USB or external 5V connected
  • Verify 3.3V LED is lit
  • Check for short circuits

Steppers Won’t Move

  • Verify motor current set in config
  • Check motor wiring (coil pairs correct)
  • Send simple G-code: G0 X10
  • Check driver not overheated
  • Verify Vmot LED is lit

Heater Won’t Heat

  • Check VFET power connected (both XT30s for high current)
  • Verify heater element resistance
  • Check correct heater pin in config
  • Verify temperature reads correctly: M105
  • Check MOSFET output LED lights when heating

SD Card Not Detected

  • Format as FAT32 (not exFAT)
  • Capacity 32GB or less
  • Try different SD card
  • Check card fully inserted

Network Not Working

  • Verify Ethernet cable connected (check link LED)
  • Confirm network.enable = true in config
  • Check IP assignment (DHCP or static)
  • Try ping from computer
  • Test Telnet (port 23) or HTTP (port 80) individually

Last updated: November 2025

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