| Processor -> | iMXRT1062 | STM32F7xx | ESP32 | MSP432E401Y | TMC129x |
|---|---|---|---|---|---|
| Board | Teensy 4.x | Nucleo-F756ZG | LaunchPad | LaunchPad | |
| MCU speed (MHz) | 600 | 216 | 2x240 | 120 | 120 |
| Floating point unit | yes | yes | yes | yes | yes |
| Non-volatile storage | Flash1 | Flash1 | Flash1 | EEPROM | EEPROM |
| Number of axes | up to 5 | up to 6 | 3 | up to 6 | up to 6 |
| Auto-squared/ganged axes17 | yes | yes | no | no | no |
| Variable spindle | yes | yes | yes | yes | yes |
| Ramped spindle | no | no | yes | yes | yes |
| Inverted spindle PWM | no | no | yes | yes | yes |
| RC Servo/ESC for spindle13 | yes | yes | yes | yes | |
| ModBus spindle14 | yes15 | no | yes | no | no |
| Spindle at speed | yes | yes | no | no | no |
| Spindle sync | yes4 | yes | no | no | no |
| Closed loop spindle RPM | no | no | no | no | no |
| Native USB streaming | yes | yes | no | no | no |
| Bluetooth streaming | no | no | yes | no | no |
| Telnet streaming (raw) | ethernet | ethernet | wifi | ethernet | ethernet |
| Websocket streaming | ethernet | ethernet | wifi | ethernet | ethernet |
| FTP to SD card | ethernet | ethernet | wifi | ethernet | no (?) |
| SD Card streaming | yes | yes | yes | no | no |
| I2C Keypad | yes | yes | yes | no | no |
| I2C IO Expander | no | no | yes | no | no |
| Digital Aux I/O | 3/416 | yes | no | no | no |
| MPG stream input | TBC | no | no | yes | yes |
| Manual tool change5 | yes | yes | yes | yes | yes |
| Automatic tool change6 | no | no | no | no | no |
| Laser PPI mode7 | yes | yes | no | no | no |
| Trinamic support8 | TBC9 | TBC9 | TBC9 | TBC9 | TBC9 |
| Runs as FreeRTOS task | no | no | yes | option | no |
| CNC BoosterPack support | yes10 | no | yes10 | 2 | 2 |
| WebUI support | no | no | yes12 | no | no |
| Compiler/IDE | Arduino | STMCubeIDE | ESP IDF | CCS | CCS |
Grbl does a lot of floating point math, a FPU will improve performance.
| Processor -> | STM32F4xx | STM32F3xx | MSP432 | TMC123 |
|---|---|---|---|---|
| Board | Blackpill / Nucleo-F411RE / Nucleo-F446RE | BlackPill | LaunchPad | LaunchPad |
| MCU speed (MHz) | 84/100/180 | 72 | 48 | 80 |
| Non-volatile storage | Flash1 | Flash1 | Flash1 | EEPROM |
| Number of axes | up to 6 | up to 6 | 3 | 3 |
| Variable spindle | yes | yes | yes | yes |
| Ramped spindle | no | no | no | yes |
| Inverted spindle PWM | no | no | yes | yes |
| RC Servo/ESC for spindle13 | yes | yes | yes | yes |
| ModBus spindle14 | no | no | yes15 | no |
| Spindle at speed | yes | no | yes3 | no |
| Spindle sync | yes4 | no | yes4 | no |
| Closed loop spindle RPM | no | no | no | no |
| Native USB streaming | yes | yes | no | no |
| SD Card streaming | TBC | TBC | no | yes |
| I2C Keypad | no | yes | yes | yes |
| I2C IO Expander | no | no | no | no |
| Digital Aux I/O | 2/216 | no | no | no |
| MPG stream input | no | no | yes | yes |
| Manual tool change5 | yes | yes | yes | yes |
| Automatic tool change6 | no | no | planned | no |
| Laser PPI mode7 | yes | no | no | yes |
| Trinamic support8 | TBC9 | TBC9 | TBC9 | TBC9 |
| CNC BoosterPack support | no | yes10 | 1 | 1 |
| Compiler/IDE | STMCubeIDE | STMCubeIDE | CCS | CCS |
| Processor -> | RP 20404 | STM32F1xx11 | SAM3X8E | SAMD21 | LPC1768/1769 | PSoC 5 | MSP430F5529 |
|---|---|---|---|---|---|---|---|
| Board | Pi Pico | Bluepill | Due | MKRZERO | Re-Arm / Bigtreetech SKR 1.3 / BTT SKR 1.4 | CY8CKIT-059 | LaunchPad |
| Non-volatile storage | Flash1 | Flash1 | Flash1 | Flash1 | Flash1 | EEPROM | no1 |
| Number of axes | up to 6 | up to 6 | up to 6 | 3 | up to 5 | 32 | 3 |
| Auto-squared/ganged axes17 | no | no | yes | no | yes | no | no |
| Variable spindle | yes | yes | yes | yes | yes | yes | yes |
| Ramped spindle | no | no | no | no | no | no | no |
| Inverted spindle PWM | yes | yes | no | no | no | no | yes |
| RC Servo/ESC for spindle13 | yes | yes | yes | yes | yes | no | yes |
| ModBus spindle14 | yes | no | no | no | no | no | no |
| Spindle at speed | no | no | no | no | no | no | no |
| Spindle sync | no | no | no | no | no | no | no |
| Closed loop spindle RPM | no | no | no | no | no | no | no |
| Native USB streaming | yes | yes | yes | yes | yes | no | no |
| SD Card streaming | yes | yes | no | yes | yes | no | no |
| I2C Keypad | yes | yes | no | yes | no | yes | no |
| I2C IO Expander | yes | no | no | yes | no | no | no |
| Digital Aux I/O | 0/816/sup> | no | no | no | no | no | no |
| MPG stream input | yes | no | no | no | no | no | no |
| Manual tool change5 | yes | yes | yes | yes | yes | yes | no |
| Automatic tool change6 | no | no | no | no | no | no | no |
| Laser PPI mode7 | no | no | no | no | no | no | no |
| Trinamic support8 | TBC9 | TBC9 | TBC9 | TBC9 | no | no | no |
| CNC BoosterPack support | yes10 | yes10 | no | yes10 | no | no | 1 |
| Compiler/IDE | VS Code | STMCubeIDE | Arduino | Arduino | MCUExpresso | PSOC Creator | CCS |
1 Plugin for I2C EEPROM or FRAM available. FRAM is faster and can sustain more write cycles than EEPROM. FRAM is reccomended for the Odometer plugin.
2 Should be fairly easy to extend.
3 In combination with ramped spindle, signals end of ramp - not programmed speed obtained.
4 To be completed (TBC), work in good progress.
5 Protocol extension, requires compatible GCode sender such as ioSender.
6 grblHAL core has functionality and HAL driver entry points are provided, needs verification!
7 Driver specific M codes added for control. PPI = Pulses Per Inch.
8 Initial version ready for TMC2130 drivers, new CNC BoosterPack design for Texas Instrument LaunchPads ready and initial testing ok.
9 Implementation provided for TMC2130, with initial focus on I2C interfaces. Work in good progress - code published.
10 Via "motherboard" that accommodates CNC BoosterPack and processor board. Prototypes made, includes 8-bit I2C GPIO expander (not available/needed for STM32F1xx or IMXRT1062). "motherboards" has option for isolated level-shifted spindle PWM or DC output. BoosterPack has an onboard EEPROM and an I2C level shifter.
11 Requires 128KB of flash (STM32F103CB), many STM32F1038B based Bluepill boards has that. Not recommended due to limited memories, use a STM32F303 or STM32F411 based Blackpill instead for a board with the same form factor as Red- and Bluepills.
12 Luc's ESP3D-WEBUI, backend partially implemented. Work in progress.
13 Set $33=50 (PWM frequency), $34=5, $35=5 and $36=10 to generate a "standard" PWM signal: 20ms repetition rate, 1 - 2ms pulse length range.
14 Currently only for Huanyang VFDs. Defaults to 19200 baud, implicit spindle at speed. Not supported for all alternative board map files.
15 Auto direction detect only.
16 Dependent on breakout board and plugin configuration.
17 Dependent on breakout board capability. ABC motors will be added from the first motor available and upward, auto-squared/ganged motors from the last and downward.
Please note that some of the capabilities should be fairly easy to port from one driver to another, but be aware some are dependent on MCU peripheral availability and thus not possible, or hard, to port.
The fastest and most deterministic MCUs seems to be iMRXT1062, MSP432E401Y and TMC129x, ESP32 is not bad but it is a bit unstable - maybe due to outstanding bugs in the ESP-IDF and the system architecture - program code is stored off chip in external serial flash.
Excel tables to markdown done with thisDaveJ web-based utility.
2021-06-22