OpenMower — Open Source RTK GPS Robotic Mower – Robot Specific Guides

Docs: YardForce Classic 500(B)

Mon, 01 Jan 0001 00:00:00 +0000

v2 Hardware Only!

This guide here is for OpenMower v2.x Hardware! If you have v1 Hardware, follow the legacy docs here , because for v1 hardware you will also need to modify the docking station!

You have v1 hardware, if:

You are using a full-size Raspberry Pi
Your mainboard shows version v0.xx

Prerequisites

Things you will need:

YardForce Classic 500(B)
Open Mower Mainboard with all modules installed (xCore, CM4, GPS, 3x ESCs)
Cover UI Board (optional)
GPS Holder (3d printed part), GPS Antenna, 2x M2,5x20 screws, 2x M4x16 screws for the GPS holder

Tools you will need:

XH connector set and some wires to crimp connectors for the emergency stops and the Cover UI board
Some basic screwdrivers for disassembly and assembly.

Step 2.4.1: Disassemble the Robot

The first step is to disassemble up the robot. This is a bit tricky in some parts, so I recommend you checking my YouTube video here: YouTube Video . The relevant time is: 2:25 - 5:08. Do not follow the video further than that, because it is outdated.

Alternatively, here is a picture guide of the disassembly process:

Unscrew top cover

Pry the cover

This is a bit tricky in some parts, so I recommend you checking YouTube video here: YouTube Video . The relevant time is: 2:25 - 5:08.

Unplug the cover

2 small wires on the front going to wheel sensors, and 1 wide wire from mainboard to cover UI board. Screwdriver is in the pictures for illustrative purposes, you can simply hold it with your hand.

Unplug the mainboard

Remove front PCB

Remove cover UI board

Info

This section assumes that you are completely replacing the stock UI board with a custom one. There is an option to reuse stock board by flashing it with custom firmware. If you are going to go this path - leave it in place. You can find more information in the Cover UI Repo *.

* Would be nice if someone could transfer this to the Knowledge Base on this website though.

Step 2.4.2: Remove Stock Electronics

You will need to remove these stock electronics:

Mainboard
Perimeter Sensor (slim PCB in the front of the robot).
All cables in the orange cover (emergency stop).

Keep the battery in place.

Step 2.4.3: Small Preparations

3.1 Cutting Plastic Tabs in the Lid

On some YardForce Classic 500 models, in the lid there are plastic tabs which are in the way when installing the OpenMower mainboard. We need to clip these tabs off. I have used a large side cutter, but you can also use a Dremel or whatever you have handy.

If your cover does not have tabs, you don’t need to do anything here.

3.2 Assemble GPS Antenna Holder

Take the GPS antenna holder and assemble it as shown in the picture.

3.3 Add new connectors to the Emergency Stop Cables

The Open Mower mainboard uses one JST XH connectors for each of the emergency stop sensors, whereas the original YardForce Classic 500 uses one large connector with all emergency stop buttons connected to it. In the following picture you can see the original connector cable.

We will now create four cables, one for each emergency stop sensor. To do this:

First, Cut the cable very close to the large connector as shown in the picture. You will need the whole length of the emergency stop cables.
Then, crimp XH connectors to the other end of the cable as shown in the picture below. Make sure to check the pinout! There is a twist in the connector!
Repeat this step for all four emergency stop sensors, so that each one has an XH connector at the end. The pinout is the same for all of them.

In the end you will have four cables with different lengths, but the same pinout.

3.4 Create a cable for the CoverUI

If you are going to use a custom CoverUI board, you will need to create a cable to connect it to the mainboard.

Take four wires with around 20 cm length.
Crimp XH connectors on both sides of the cables as shown in the picture. The connections are “straight through”, so pin 1 connectos to pin 1 on the other side and so on.

Step 2.4.4: Install OpenMower Electronics

Now you can install the OpenMower mainboard and the GPS antenna holder we prepared earlier.

Put the mainboard into the mower just as the original board was installed
(in the rear it sits between plastic tabs, on the front there are two screws holding it in place).
To fit the GPS holder into the mower, you need need to remove two of the white plastic cable ties by just pulling them upwards. Then plug it into the corresponding holes and fix it with one screw you saved earlier.
Connect all cables as shown in the picture and the list below.

When finished, it should look like this:

The connections are as follows:

Mower Motor Sensor
Main Motor Connector (Drive motors, mower motors, sensors)
Power Connector
Charging Contacts
Emergency Stop Button in the Lid (left / right side doesn’t matter)
Emergency Stop Button in the Lid (left / right side doesn’t matter)
USB Connector on the Rear of the Robot
Cover UI Board in the Lid (optional)
GPS Antenna
Lift Sensor (left / right side doesn’t matter)
Lift Sensor (left / right side doesn’t matter)

Step 2.4.5: Install external WiFi Antenna (optional)

If you want to use an external WiFi antenna for better reception, installation is simple.

Prerequisites

Things you will need:

WiFi Antenna Mount: 3D printed part available on Printables
Two Screws you can use the screws from the front sensor we removed earlier
WiFi Antenna with Cable You can get it from Amazon

Steps:

Mount the antenna to the holder
Mount the holder to the mower using the two screws
Connect the antenna to the CM4 board
Zip tie the cable to the corner of the PCB

Step 2.4.6: First Startup

It’s time to power the robot up by hitting the switch at the back of the robot.

Warning

If you see / smell anything unexpected, turn the switch off immediately!

This includes but is not limited to:

Smoke / Fire
Smell of hot electronics
Blown Fuses

Some battery packs don’t like the inrush current and will turn off immediately. If this happens, you can try to turn the switch off and on again and it should work.

Once turned on, LEDs should start blinking on the ESCs, the GPS, the xCore board and the mainboard. Keep the robot turned on for at least five minutes to maker sure the CM4 boots up properly. It does setup during the first boot.

Info

It’s a good idea to place the mower into the docking station, so that the battery doesn’t drain.

In this state, the battery does not charge, because the core board does not have the correct firmware installed, but the docking voltage will still be used to power the electronics, so the battery will not drain.

If everything seems healthy, proceed to the Software Setup .

Otherwise, stop here and ask for help on the Discord server.

Docs: SABO / John Deere

Mon, 01 Jan 0001 00:00:00 +0000

Prerequisites

Things you will need:

SABO MOWiT 500F or John Deere Tango E5
Open Mower V2 Carrier Board for SABO with all modules installed (xCore, CM4, GPS, 3x ESCs)

Tools you will need:

M10 ratchet for the cover
5mm Allen key for the blade
Torx T30 for the mainboard mount/holder
Torx T20 for the mainboard

Step 2.4.1: Open the mower and remove the OEM mainboard 🔓

Place the mower on its back and remove the six 10 mm screws from the housing.
Remove the blade with the 5mm Allen key (right‑hand thread). Use gloves and secure the blade while loosening.
Hold the housing together with both hands and place the mower back on its wheels.
Slightly open the cover on the handle (rear) side by a few centimeters.
Using a flashlight, disconnect the display ribbon cable(s):
- Series‑I: two ribbon cables going to the CoverUI. Each plug has small side locks; press to release, then unplug from the mainboard.
- Series‑II: one ribbon cable; pull it straight out from the mainboard (no release locks).
You can now open the cover further. A single cable from the cover’s charging contacts goes toward the mainboard. Before the mainboard there is a 2‑pin Molex plug; press to unlock and disconnect it. Put the cover aside for later modification and reassembly.
Disconnect all remaining cables from the OEM mainboard. Many plugs have a latch; press to release before pulling.
The OEM mainboard is mounted on a black plastic mainboard holder. On its back side are two larger Torx T30 screws. Remove them to lift out the mainboard together with the holder.
Remove the OEM mainboard from the holder by unscrewing the Torx T20 screws.

Step 2.4.2: Mount prepared parts

Assemble the previously prepared parts :

Mount your prepared UM9x GPS module to the carrier board and attach the IPEX/SMA cable (usually included with the UM9x) as shown:
Mount your xCore + CM4 (+ optional heatsink) combo to the carrier board (if not already mounted)

Step 2.4.3 (optional): Install Wi‑Fi adhesive antenna 📶

The Wi‑Fi adhesive antenna can be placed as shown:

Step 2.4.4: Assemble carrier board with mainboard 🔩

Now that all modules are prepared and mounted, fasten the carrier board to the mainboard holder.
If you have fewer screws than holes, prioritize holes close to the larger connectors!
Mount the carrier board + mainboard-holder back into the mower and fasten it with the two T30 screws.
Carefully connect all plugs. Some plugs fit into multiple counterparts, verify the labels or use this plug overview:

Series-I Plugs Series-II Plugs

Note: some plugs are rotated — do not force any connector!

Step 2.4.5: Install GPS antenna (e.g. HA/HX‑901) on the cover 🛰️

An alternative non-destructive internal holder was designed by STS . Check the Discord discussion for more details and STL files if available.

Drill a 6.5–7 mm hole in the cover approximately at the position as shown in the images.
Install the (included) 30-40cm SMA extension cable. Ensure the SMA bulkhead protrudes far enough so the HA/HX‑901 can fully engage and make good contact; if in doubt, omit one washer/spacer on the inside to gain thread length.
Seal it from the top with silicone or a similar sealant. Don’t use too much sealant, so the HA/HX‑901 can still be screwed on later.
Also seal the inside thoroughly to prevent any water ingress. On the inside use sealant rule: More is better
Allow sufficient time for the sealant to cure before proceeding.

Step 2.4.6: Close the housing ✅

Place the cover back onto the mower. Let the front engage slightly, but keep the rear open enough to:
1. Connect the GPS antenna cable to the carrier board
2. Reconnect the docking‑contact cable
3. Finally, reconnect the CoverUI ribbon cable(s)
Close the cover completely so it fits and latches evenly all around
Hold the housing together with both hands and turn the mower back onto its back
Reinstall and fasten the six 10 mm hex‑head screws
Do not install the blade yet
Put the mower back on its wheels
Finally, screw the HA/HX‑901 antenna onto the cover

Step 2.4.7: First Startup

It’s time to power the robot up by hitting the switch at the back of the robot.

Warning

If you see / smell anything unexpected, turn the switch off immediately!

This includes but is not limited to:

Smoke / Fire
Smell of hot electronics
Blown Fuses

Once turned on, it will take approximately 10 seconds before the LEDs and LCD start to show signs of life. Keep the robot turned on for at least five minutes to make sure the CM4 boots up properly. It performs setup during the first boot.

Info

It’s a good idea to place the mower into the docking station, so that the battery doesn’t drain and can charge.

If everything seems healthy, proceed to the Software Setup .

Otherwise, stop here and ask for help on the Discord server.

Docs: v1 Hardware Guide (Legacy)

Mon, 01 Jan 0001 00:00:00 +0000

v1 Hardware Only!

Only follow the Docking and Robot Modification Guide from the old docs, you can use the current OpenMower OS! You have v1 hardware, if:

You are using a full-size Raspberry Pi
Your mainboard shows version v0.xx

OpenMower — Open Source RTK GPS Robotic Mower – Robot Specific Guides

Docs: YardForce Classic 500(B)

v2 Hardware Only!

Prerequisites

Things you will need:

Tools you will need:

Step 2.4.1: Disassemble the Robot

Unscrew top cover

Pry the cover

Unplug the cover

Unplug the mainboard

Remove front PCB

Remove cover UI board

Info

Step 2.4.2: Remove Stock Electronics

Step 2.4.3: Small Preparations

3.1 Cutting Plastic Tabs in the Lid

3.2 Assemble GPS Antenna Holder

3.3 Add new connectors to the Emergency Stop Cables

3.4 Create a cable for the CoverUI

Step 2.4.4: Install OpenMower Electronics

Step 2.4.5: Install external WiFi Antenna (optional)

Prerequisites

Things you will need:

Steps:

Step 2.4.6: First Startup

Warning

Info

Docs: SABO / John Deere

Prerequisites

Things you will need:

Tools you will need:

Step 2.4.1: Open the mower and remove the OEM mainboard 🔓

Step 2.4.2: Mount prepared parts

Step 2.4.3 (optional): Install Wi‑Fi adhesive antenna 📶

Step 2.4.4: Assemble carrier board with mainboard 🔩

Step 2.4.5: Install GPS antenna (e.g. HA/HX‑901) on the cover 🛰️

Step 2.4.6: Close the housing ✅

Step 2.4.7: First Startup

Warning

Info

Docs: v1 Hardware Guide (Legacy)

v1 Hardware Only!

The v1 guide is here .