Changing EEPROM settings

Last Update: 26 June 2020

For in-depth documentation on all of the settings in GRBL and what they mean, visit:

You can make changes to your machine’s settings by changing the values in your EEPROM. These are settings that will persist even after you power off your machine and control things like the maximum speed, the acceleration, steps per mm, and more.

Start by sending the command “$$” to your machine. Your console will give you a list of values.


Value Purpose
$0=10 Step pulse time [microseconds]
$1=100 Step idle delay [milliseconds]
$2=1 Step pulse invert [mask]
$3=5 Step direction invert [mask]
$4=1 Invert step enable pin [boolean]
$5=0 Invert limit pins [boolean]
$6=0 Invert probe pin [boolean]
$10=1 Status report options [mask]
$11=0.010 Junction deviation [millimeters]
$12=0.002 Arc tolerance [millimeters]
$13=0 Report in inches [boolean]
$20=0 Soft limits enable [boolean]
$21=0 Hard limits enable [boolean]
$22=0 Homing cycle enable [boolean]
$23=0 Homing direction invert [mask]
$24=25.000 Homing locate feed rate [mm/min]
$25 = 500.000 Homing search seek rate [mm/min]
$26 = 250 Homing switch debounce delay [milliseconds]
$27 = 1.000 Homing switch pull-off distance [millimeters]
$30 = 30000 Maximum spindle speed [RPM]
$31 = 0 Minimum spindle speed [RPM]
$32 = 0 Laser-mode enable [boolean]
$100 = 200.000 X-axis travel resolution [step/mm]
$101 = 200.000 Y-axis travel resolution [step/mm]
$102 = 200.000 Z-axis travel resolution [step/mm]
$110 = 4000.000 X-axis maximum rate [mm/min]
$111 = 4000.000 Y-axis maximum rate [mm/min]
$112 = 3000.000 Z-axis maximum rate [mm/min]
$120 = 750.000 X-axis acceleration [mm/sec^2]
$121 = 750.000 Y-axis acceleration [mm/sec^2]
$122 = 500.000 Z-axis acceleration [mm/sec^2]
$130 = 812.000 X-axis maximum travel [millimeters]
$131 = 812.000 Y-axis maximum travel [millimeters]
$132 = 105.000 Z-axis maximum travel [millimeters]


To change a setting, simply send the command that corresponds to what setting you want to change. For example, if I want to set my maximum feed rate in the Z-axis to 1500mm/min, then I would send the command “$112=1500”.

If you’re using UGS, you can also directly import the LongMills firmware settings using this downloadable file: LongMill UGS Firmware Config

For advanced users, or users that want to add additional functionality such as with end stops and lasers, you may make changes to these settings.