Using MRGui on Windows

MRGui is our configuration utility for MRBus based devices.  It simplifies the process of setting the various EEPROM configuration options for each node, using a user-friendly GUI that runs on Windows, Mac, or Linux.  In addition to setting EEPROM configuration options, MRGui can also be used for general purpose programming of AVR microcontrollers.  The instructions below take you through the steps to get up and running with MRGui on a Windows platform.

Step 1 – Obtain a Programmer

Before configuring or reprogramming the firmware in an MRBus device, an AVR programmer is required.  Some products, such as the Interlocking-In-A-Box, come standard with a programmer.  For others, you will need to purchase a compatible programmer.  The ISE AVR Programmer is our recommended programmer, because of its low cost and ease of use, and this guide is written assuming you are using that one.  For advanced users who choose to use a different programmer, it is assumed you will know which options to select later on in the guide.

Step 2 – Download MRGui

The latest MRGui release can be found on GitHub.  For Windows, download the latest release.  Once downloaded, right-click on the ZIP file and select Extract All.  Select the path where you would like the program extracted.  There is no installer at the moment, so be sure to remember where the files were extracted.


Navigate to the directory where you extracted the files.  Double-click the mrgui icon to start the program.  The first window will ask you to select the MRBus node to configure.  For example, if configuring the Interlocking-In-A-Box, select the MRB-IIAB node and click OK.  The main MRGui window will now open.

Step 3 – Installing the Driver

Before the programmer can be used with MRGui, a USB driver must be installed.  MRGui comes with the necessary driver files and installer.  To install the driver, first connect the programmer to the computer’s USB port.  Windows will detect the device and attempt to install a driver.  However, it will fail with the following message:


Have no worry, this is normal.  From the MRGui window, confirm that “ISE AVR Programmer” is selected in the Program -> Programmer menu.  Then select Program -> Install Driver… You may receive a warning asking if you want to allow the program to make changes to your computer.


Select Yes to continue.  A new window will appear and the driver installation will begin.  Be patient, it may take a minute or so for the installation to complete.


Once complete, you should get an Installation Succeeded message:


At this point, the driver is installed and you are ready to use MRGui to configure your device!


Q: When installing the driver, I get an Installation Failed message.  What next?


A: Follow the instructions in the message box and try again.  If that doesn’t work, contact us and include the Error and Exit Code information at the bottom of the box.

Q: What do I do if I get a “Could not find USBtiny device” error message when reading from or writing to a device?


A: First, check that the programmer is plugged into the computer’s USB port.  If so, make sure that the correct programmer is selected.  Did you run the “Install Driver…” utility and receive a success message at the end?  Finally, if the programmer is plugged in and the driver installation succeeded, try unplugging and re-plugging the programmer.  If none of these resolve the problem, then contact us, including as much information as possible (screenshots are always helpful).

Q: When reading or writing to an MRBus node, I get an error saying avrdude.exe has stopped working.  Is this a problem?


A: No, this is typically not a problem.  Unfortunately, the version of the third-party software (avrdude) used to communicate with the programmer has some bugs where it will sometimes crash at the end of a transaction.  In all cases we have seen, the data has been properly transmitted, so you can safely ignore the message.

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