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The firmware runs on an Arduino microcontroller and is written in C++. The firmware is usually flashed to the Arduino via FarmBot OS.

Internally used commands

The commands and responses on this page are used for communication between FarmBot OS and the FarmBot Arduino Firmware. Outside of that internal communication, commands on this page can only be sent by disconnecting the Arduino from the Raspberry Pi and connecting a USB cable from a computer directly to the Arduino.

FarmBot OS communication via Farmware and the Message Broker consists of higher-level CeleryScript commands, not the commands listed on this page.

Sending commands

Commands are sent to the Arduino using the command code and number, any arguments (separated by spaces), and a CR/NL (\r\n).

For example, to set parameter number 101 to 1, you would send F22 P101 V1\r\n, where F22 is the write parameter command, P101 is the parameter argument, V1 is the value argument, and \r\n is the CR/NL.

For this example, the firmware will respond with (comments excluded):

R08 *F22 P101 V1*     // the command received (echo)
R01 Q0                // command started
R21 P101 V1 Q0        // report parameter 101 value: 1
R02 Q0                // command finished successfully

The Q at the end of the responses designates the command queue number. Q + a number can be appended to any command sent and the responses will include the same Q number provided.

Commands that can be sent begin with G or F. Responses and status reports received from the Arduino begin with R.

General command responses
R08 Echo
R09 Invalid
R01 Started
R04 Running
R02 Finished successfully
R03 Finished with error
R07 Movement retry
Idle and status responses Description
R00 Ready
R87 Locked
R88 Config not approved (use F22 P2 V1 to approve manually)

Emergency stop

Command Description
E Emergency stop
R87 Locked
F09 Reset emergency stop (unlock)


Movement reports X Y Z
R81: report endstops XA: end stop 1 (0/1)
XB: end stop 2 (0/1)
YA: end stop 1 (0/1)
YB: end stop 2 (0/1)
ZA: end stop 1 (0/1)
ZB: end stop 2 (0/1)
R82: current position (mm) X Y Z
R84: encoder position (mm) X Y Z
R85: encoder position (edges) X Y Z
timeout R71 R72 R73
R05: axis state X0: idle
X1: starting motor
X2: accelerating
X3: cruising
X4: decelerating
X5: stopping motor
X6: crawling
Y0: idle
Y1: starting motor
Y2: accelerating
Y3: cruising
Y4: decelerating
Y5: stopping motor
Y6: crawling
Z0: idle
Z1: starting motor
Z2: accelerating
Z3: cruising
Z4: decelerating
Z5: stopping motor
Z6: crawling

Move to

G00: Move to location X Y Z
axis location
unit: mm
default: 0
unit: steps/s
default: max speed


// Move to (0, 0, 0) at normal speed

// Move to (100, 200, 300) at normal speed
G00 X100 Y200 Z300

// Move to (100, 200, 300) at specified axis speeds
G00 X100 Y200 Z300 A400 B500 Z600
Command Description
G28 Move each axis to home (zero) in order: Z, Y, X


Finds zero for an axis. Requires the use of encoders or end-stops. For more information, see Calibration and Homing.

Find home (zero) X Y Z
Command F11 F12 F13
Response: Homing complete R11 R12 R13

Calibrate axis

Measures an axis length and then finds zero for that axis. Requires the use of encoders or end-stops. For more information, see Calibration and Homing.

Calibrate axis X Y Z
Command F14 F15 F16
Response: R06 R06 X0: idle
R06 X1: moving to home
R06 X2: moving to end
R06 Y0: idle
R06 Y1: moving to home
R06 Y2: moving to end
R06 Z0: idle
R06 Z1: moving to home
R06 Z2: moving to end

Zero axis

Sets zero for an axis. For more information, see Calibration and Homing.

Command X Y Z
F84 X1: set to zero
X0: don’t set to zero
Y1: set to zero
Y0: don’t set to zero
Z1: set to zero
Z0: don’t set to zero

Pin control

Command Pin Number Value Mode
Read pin F42 P   M0: digital
M1: analog
Write pin F41 P V (0-1 digital, 0-255 analog) M0: digital
M1: analog
Set pin input/output mode F43 P   M0: input
M1: output
M2: input pullup
Set servo angle
(only pins 4, 5, 6, and 11)
F61 P V (0-180)  
Response (report pin value) R41 P V (0-1 digital, 0-1023 analog)  

Pin assignment

For Arduino and Farmduino board pin assignments, see src/pins.h.

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